BIOL 2306 LIVING PLANET Concepts and Questions
Twelfth Edition
Written by:
Bernice Speer Betsy Maxim Sarah Strong
July 2016
ISBN BIOL2306216
BIOL 2306 LIVING PLANET Concepts and Questions
Twelfth Edition by
Bernice Speer Betsy Maxim Sarah Strong
July 2016
Student’s Name:
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Section Number:
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Instructor:
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Unless otherwise noted, most images of organisms are taken from Seashore Life Illustrations, Animal Illustrations, and Insects published by Dover Publishing. Any illustration marked as “Biodidac” comes from Biodidac, a bank of digital resources for teaching biology, on the web at: http://biodidac.bio.uottawa.ca/
BIOL 2306 THE LIVING PLANET STUDY GUIDE 12th edition TABLE OF CONTENTS Preface and Copyright Notice ....................................................... i How to Use This Study Guide....................................................... ii Blank World Map .......................................................................... iv Introduction.................................................................................... 1 Episode 1...................................................................................... 29 Episode 2...................................................................................... 47 Episode 3...................................................................................... 69 Episode 4...................................................................................... 93 Episode 5.................................................................................... 116 Episode 6.................................................................................... 134 Episode 7.................................................................................... 154 Episode 8.................................................................................... 178 Episode 9.................................................................................... 202 Episode 10.................................................................................. 219 Episode 11.................................................................................. 240 Episode 12.................................................................................. 257
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PREFACE This manual has been written especially for the Biology 2306 LIVING PLANET course offered at Austin Community College. Although various editions of the Living Planet Study Guide have been available for many years, the course required substantial revision in 1996, when the book Living Planet written by David Attenborough was taken out of print. Since then, we have revised the manual several times. This manual, Living Planet: Concepts and Questions, is designed to supplement the video programs. We are indebted to David Attenborough for his genius in developing this series of programs. We would also like to thank our colleagues for their input and revisions on the Living Planet Study Guide: Steve Muzos and Steve Bostic. We have included several web sites in the manual. Keep in mind that web sites come and go. If a web link is not working, use a search engine to hunt for the topic. Bernice Speer Professor of Biology Round Rock Campus Austin Community College
Betsy Maxim Professor of Biology Round Rock Campus Austin Community College Sarah Strong Professor of Biology Riverside Campus Austin Community College
COPYRIGHT NOTICE This manual is published by Austin Community College, with permission of the authors. The authors retain the copyright for their original work. All rights are reserved. No part of this book may be used or reproduced in any manner whatsoever without written permission of the authors and ACC.
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How to Use This Study Guide GENERAL INFORMATION The course LIVING PLANET is based on a series of twelve video episodes produced by the BBC and narrated by David Attenborough. This study guide has been written to guide you through the videos.. LIVING PLANET is an overview of world ecology. Over the course of this semester, you will be introduced to several ecosystems, such as deserts, grasslands and mountain peaks. David Attenborough, the narrator, discusses where these ecosystems are found and the features of each. He also examines the plants and animals that are found there and discusses any special adaptations that allow them to be successful. Each section has introductory material about the concepts covered in the corresponding video episode. Read this material before watching the video. The introductory material is followed by a series of questions for you to complete as you watch the video. As you go through the video questions, you will find corrections and additional information interspersed among the questions. You need to pay attention to this information because it is part of the course materials. There are twelve video episodes in LIVING PLANET. As a general rule, one ecosystem is discussed in each episode. For example, Episode 3 discusses the different types of temperate forests -- coniferous forests and broad-leaved forests. Attenborough discusses the location of the coniferous forests, the climate and the characteristics of conifers that allow them to survive under these conditions. He then discusses conditions and characteristics of broad-leaved forests. As you watch the videos, pay close attention to the characteristics of each ecosystem. Look for the problems that face organisms and different ways plants and animals have solved the problems. Look for adaptations that have occurred in the organisms. Adaptations are explained in Part V of the introduction. Remember, this is global ecology. You should know where these ecosystems are found and any differences between similar ecosystems. For example, where are the coniferous forests located? How are they different from broad-leaved forests? Where are the broad-leaved forests found? What are the differences between coniferous forests of Europe and coniferous forests of North America? Are there any differences between different types of broad-leaved forests?
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Don't just ask how they are different. Start asking why they are different. Are the differences due to temperature? Rainfall? Altitude? Does one desert get more rainfall than another desert? Does one grassland have better soil than another? ADDITIONAL REFERENCES If you need or want additional information about topics covered in this course, don't forget to use the ACC Library. Ecology books will have information on ecological principles. Geology books will discuss fossils, volcanoes, volcanic islands and continental drift. Many students have bought the companion book Living Planet from online sources, such as amazon.com or barnesandnoble.com. If you have problems understanding his British accent, you might find the book to be very useful. And, of course, there is always the internet. Many people have problems with world geography. If this is true for you, you are not the only one. Apparently, most Americans cannot pick out which continent is Africa, much less know where to find the Himalayas or the Hebrides. Don't despair. Use Google. There are many world atlases in the ACC Libraries. There is also an excellent map in the back of Attenborough's book, right before the index. You will have a much clearer mind picture of where deserts or mountains or grasslands are located. Throughout this study guide, we refer you to web sites that will supplement the materials. Check with your instructor to see if you need to read these articles as part of the class. If you want additional information, these are a good place to start. A former student sent this great web site that is cosponsored with the National Geographic Society. It features an interactive map of the terrestrial ecoregions of the world, many of which you will visit in this course with David Attenborough. One feature of the site is images from the various areas as well as information on the region. We highly recommend it to you: http://www.nationalgeographic.com/wildworld/terrestrial.html
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INTRODUCTION Living Planet is a course that focuses on world ecology, which is the study of interactions among organisms in different habitats on Earth. Ecology studies interactions among living and non-living components of environments. Most people are familiar with the living components, the living things present in the environments which include animals, plants, bacteria, fungi and other microorganisms. But there’s more than just the living stuff. The non-living components are crucial. These include things such as climate, the amount of sunlight, the availability of water, the type of soil and many other physical and chemical characteristics of environments. In order to study ecology, you need some basic knowledge of both the living and nonliving components. This introduction is designed to help you understand some basic concepts that will be important throughout the semester.
I. Geography This section contains some basic information you need to know about geography to understand the material presented in the Concepts and in the video Episodes. Many of the features are illustrated on Maps 1 and 2 below. You can use the blank world map on page iv to practice identifying some of the features described here. A. Global Terms 1.
Equator - an imaginary line around earth midway between poles
2.
Poles (North Pole and South Pole) - the northern and southern-most points on the earth
3.
Longitude - units of east-west measurement around the earth. These are the vertical lines. Longitude measures where a place is (east or west) of a vertical line going through Greenwich, England, which is designated as 0
4.
Latitude - units of north-south measurement around the earth. These are the horizontal lines that go around the earth. The location is always given as latitude first, then longitude. This basically measures where a place is relative to the equator. This is a simple but useful website that explains latitude and longitude: http://geography.about.com/cs/latitudelongitude/a/latlong.htm
5.
Hemisphere - half of the earth (north/south or east/west)
6.
Axis - an imaginary line running through the earth between the poles
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Rotation - movement of the earth around its axis
8.
Revolution - movement of the earth around the sun (orbit)
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B. Physical Geography 1.
Continent - a large land mass. There are 6 continents: Africa, Antarctica, Australia, Eurasia, North America, South America.
2.
Ocean - a large body of salt water. There are 5 oceans: Atlantic, Antarctic, Arctic, Indian, Pacific.
3.
Sea - usually refers to a body of salt water, smaller than and often more shallow than an ocean (examples: Baltic, Caribbean, Mediterranean)
4.
Atmosphere - the air above the surface of the earth
5.
Altitude - height of an object above the average level of the oceans (mean sea level)
C. Other Important Map Features 1.
Arctic Circle: An imaginary line that marks the lower boundary of the area we call the Arctic. This is the southern-most latitude in the northern hemisphere with a 24-hour day at least once a year.
2.
Antarctic Circle: An imaginary line that marks the upper boundary of the area we call the Antarctic, the northern-most latitude in the southern hemisphere with a 24-hour day at least once a year.
3.
Tropic of Cancer: An imaginary line that marks the northern-most latitude at which the sun is directly overhead during the June solstice.
4.
Tropic of Capricorn: An imaginary line that marks the southern-most latitude at which the sun is directly overhead during the December solstice.
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The Earth Map 1
This view of the Earth shows the major map features listed above. Locate the equator. Then look for the Tropic of Cancer in the Northern Hemisphere and the Tropic of Capricorn in the Southern Hemisphere. Locate the North Pole and the South Pole on the map. Then find the Arctic Circle and the Antarctic Circle. These major lines of latitude play an important role in understanding climate. For example, the equator gets more sunlight than any other location on the planet. The poles get the least amount of sunlight. Since sunlight warms the surface, it is no surprise that places along the equator are warm and places near the poles are very cold. You can also see from this map that there are oceanic habitats in addition to terrestrial (land-based) habitats. © Speer, Maxim and Strong
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The Earth Map 2
This view of the Earth shows a clear view of longitude. Start with the longitude line at 90 (this would be 90 W). As you move from right to left (east to west), the numbers get bigger. You are moving west of the 90 longitude line. You can also see latitude. Start at the equator, which is shown as 0. As you move north from the equator towards the Arctic, notice how the numbers increase and become 15N, 30N, etc. As you move south from the equator towards the Antarctic, the numbers become 15S, 30 S, etc. © Speer, Maxim and Strong
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II. Biogeography A. What is biogeography? Biogeography is a branch of science that attempts to explain the distribution of species on the earth. In the broadest sense, it not only explains why each currently living species is located where it is, but also reaches back in time to explain why extinct species lived where they did and why they don’t live there any more. Biogeographers also use principles they have learned from living and extinct species to make predictions about the future distribution of species or about when a species might become extinct. Biogeography looks at many different factors to find explanations for species distribution: physical conditions, evolutionary history, barriers, and species interactions. These factors can usually explain why one species lives in one place and not everywhere on the earth. Think about what the earth would be like if species distribution were random, if none of the factors mentioned above had anything to do with where a species lives. We could simulate a situation like this by putting the names of all species on pieces of paper and putting them in a box. Then for each type of habitat, we would pull out a certain number of slips of paper that would determine what species would live there. We might get polar bears in the tropical rain forest, orchids on the tundra, oak trees on the bottom of the ocean, or whales on the prairie. An even more general approach would be to distribute all species everywhere. But these approaches show us what we already know--that living things cannot survive just anywhere. Whales can die when out of the water for even a few hours, so they would never survive on land. On the other hand, trees wouldn’t do well on the bottom of the ocean where there is no light for photosynthesis. The basic theme of the Living Planet video series, and of this course, is examining the reasons behind the distribution of plants and animals on the earth. The approach taken in each episode is to look at a habitat like desert or grassland and to examine some of the adaptations that allow species to survive there. This part of the study guide will explain each group of factors in advance so that the examples seen in the videos will make more sense. Physical factors such as temperature, light and moisture (for terrestrial organisms), or salinity, light and water pressure (for aquatic organisms) are one of the main things that determine where on the earth a species can survive (section B). Over the millions of years of the earth’s history, the continents have been moving around, changing the climate of the land masses and joining or separating bodies of water. As the land masses moved, they took species with them, altering their previous distribution (section C1). Species distribution is also determined by where a species could spread, or disperse, from its point of origin. Dispersal of a species has been limited by barriers like rivers, mountain ranges, glaciers and oceans (section C2). Interactions between species may have one of two effects on species distribution. If one species competes with another, one or both of their ranges is likely to be smaller than the range determined by physical conditions and barriers alone. On the other
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hand, if one species depends on another, we are likely to find them always in the same place.
B. Physical Biogeography 1. Tolerance Each species on the earth has a range of physical conditions within which they can survive that can be called their tolerance zone. This zone can be described for many physical factors (like temperature or pH) by a tolerance graph:
A. B. C. D.
Optimal range - range of physical factor within which most individuals survive Stress zones - zones at ends of optimal range in which very few individuals survive Tolerance limits - upper and lower limits beyond which no individuals survive Lethal zones - zones outside of tolerance limits where no individuals survive
The optimal zone is the range of a physical factor (like temperature) within which most individuals of a species can not only survive but also thrive. Most members of a species live on a part of the earth that has physical conditions that are within the species’ optimal range. Just above and below the optimal zones are regions in which the physical conditions are not optimal, but in which some individuals of the species would still be able to survive. These are called stress zones because they cause some form of physical stress in the organisms living under those conditions. Let’s look at a specific example, a plant. This plant species has an optimal temperature range of 15 to 25 degrees Celsius (C). At temperatures above 25C, the © Speer, Maxim and Strong
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heat causes the plant to lose more water by evaporation through its leaves than it can replace through its roots. Its leaves wilt, and photosynthesis (the process by which the plant uses solar energy to make food for itself) stops. If the plant is in these conditions for long enough, it will make less food than individuals of the same species that are living in their optimal temperature zone. It will not be able to grow as fast, and may not be able to make flowers or seeds at all. At the other end of the temperature range, individuals of this species living in regions where the temperature is cold (less than 15C) have other problems. The cold slows down chemical reactions in their cells, making photosynthesis, growth, and reproduction slow down also. In this case, the plants living in cold regions have the same end result as plants living in hot regions. Many individuals of this species will not be able to tolerate the stress caused by either heat or cold, and they will die. Even if they don’t die, they won’t make as many seeds as individuals living in the optimal temperature zone, and fewer seeds means fewer individuals in the next generation. So the number of living individuals in the stress zones is always smaller than the number living in optimal conditions. Going back to the graph, the tolerance limits are the absolute limits above or below which NO members of the species could survive. Outside of the tolerance limits are the lethal zones, where no members of the species can live. For the plant, if the upper tolerance limit for temperature is 30C, any plant subjected to that temperature for more than a few minutes or hours would die. Tolerance is the most basic factor that determines where on the earth a species can live. The other factors (evolutionary history, barriers, species interactions) can limit a species’ distribution even more, but they can never allow a species to live outside of its tolerance limits. Because of this, we can make a general statement that the greater the tolerance range, the larger the geographical area over which the species is distributed. 2. Limiting Factors A limiting factor is any condition or factor that exceeds an organism's tolerance range. Depending on where it lives, each species is subject to several limiting factors. For terrestrial organisms (species that live on land), the limiting factors are usually climate (temperature and precipitation), light, soil structure and nutrients. Other factors such as oxygen level in the atmosphere and periodic fires are more specific limiting factors for some species. Aquatic organisms (those that live in the water) are limited by salinity, temperature, current, pH, dissolved oxygen, light, and water nutrient level. Altitude affects not only temperature (see below) but also the level and timing of precipitation. The physical characteristics of an organism’s environment (temperature, pH, light, etc.) are called abiotic factors. But the environment also contains biotic (living) components. The biotic components include all living organisms found in a particular region. This includes cyanobacteria (or blue greens), bacteria, algae, plants, fungi and animals. The living organisms have important roles in an ecosystem. Bacteria and © Speer, Maxim and Strong
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fungi are decomposers, responsible for breaking down urine, feces, dead wood, fallen leaves and carcasses into their smallest components. This process returns nutrients (such as carbon, oxygen, iron, nitrogen, potassium) to the environment so the nutrients can be reused. Producers include plants, cyanobacteria, algae and other organisms that carry out photosynthesis, using water, carbon dioxide and the energy of sunlight to produce food. Herbivores are animals that get their food by directly eating the photosynthesizers. Other animals are predators, eating the herbivores. In many cases, the types of plant life will determine the types of animals found in an area. If an animal such as a fox squirrel needs acorns and nuts to survive winter, you will not find fox squirrels living in the desert where the plant community is composed of cacti. The video episodes will tell you about how organisms live under different physical (abiotic) conditions. But for the most part they won’t tell you why those particular conditions exist in specific regions of the earth. That’s the purpose of the next section. 3. Physical Conditions that Affect the Distribution of Species The distribution of terrestrial (land-living) species is affected mainly by climate and soil characteristics: a. Climate Climate has two main components: temperature and precipitation. Both of these vary in different parts of the earth due to several factors, although not necessarily the same factors for both. Ocean currents and wind patterns modulate basic temperature and precipitation patterns, mostly by redistributing air and water.
Temperature Temperature limits the distribution of species because if it is too low it lowers an organism's metabolism too much for it to maintain cellular activity. In extreme cases, the formation of ice crystals inside cells when they freeze damages the cell so that even if it thaws out, it cannot survive. On the other hand, temperatures that are too high cause damage to proteins in the organism's body, a condition that can also be fatal. Because temperature varies daily and seasonally in many parts of the earth, the species that live there have to be able to tolerate a range of temperatures. The temperature in any given place on the earth depends mainly, but not exclusively, on its latitude and its altitude:
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o Effect of Latitude on Temperature As you move either north or south away from the equator, two things happen to make the temperature decrease: 1) solar radiation is spread over a larger area due to angle of incidence of solar radiation 2) solar radiation has to pass through more of the atmosphere before it hits the earth's surface o Effect of Altitude on Temperature As you move up from mean sea level, the temperature generally decreases. This is because as you go higher, the atmospheric pressure decreases, which means the air is less dense (there are fewer molecules per liter), and that means that the molecules of the air cannot hold as much heat. o Effect of Ocean Currents on Temperature Ocean currents are defined as the movement of surface water caused by the rotation of the earth and the action of wind on the water. The currents affect air temperature in coastal more strongly than inland areas. The Gulf Stream is a current in the North Atlantic Ocean. It sweeps downward past Africa, then turns when it reaches the equator and moves westward towards South and Central America. Those land masses in turn deflect the current northwards along the eastern coast of the United States. From there it continues eastward across the Atlantic towards Europe, which deflects it southwards past the coast of Africa. It makes a big clockwise circle in the North Atlantic Ocean. As it flows along the equator, the water warms up. Later, when this warm water moves along the eastern coast of the U.S. and past Europe, it gives up some of the heat. The climates of the coastal areas that are passed by the Gulf Stream are much warmer and more mild than they would be expected to be based only on their latitude and altitude. Another example is the Humboldt Current. It carries cold polar water from the Antarctic up past the western coast of South America. The effect there is to make the climate cooler than would be expected based on latitude and altitude.
Precipitation Precipitation is the amount of rain, snow, sleet or any water that falls from the sky. In many parts of the earth, there is seasonal variation in the amount of precipitation (such as wet in the winter but dry in summer) or the form of precipitation (snow in the winter and rain in the summer). Here are some of the factors that determine how much precipitation a given area of the earth receives:
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o Effect of Latitude on Precipitation At the equator the sun has its greatest effect and it heats up the air, which rises. It also evaporates water from the planet’s surface into the air. As the air rises, it cools off. When it cools off, the moisture condenses into larger droplets of water and falls back onto the surface as rain. Therefore, areas close to the equator have high rainfall. The air, which is much dryer now, continues to rise and is forced to turn north or south. At about 30 degrees north and south of the equator, the cool, dry air descends back towards the surface. This is called a subsidence zone. Most of the deserts of the world lie near 30 degrees north or south because of the dry air. Solar energy creates three of these circular air movement patterns called convection cells in each hemisphere--north and south. But only the cell nearest the equator (the one described above) is used as an explanation for climate later in this book. o Effect of Rain Shadows on Precipitation Rain shadows exist in areas where mountain ranges block the prevailing winds coming inland from the ocean. For example, on the west coast of North America the wind is coming from the west across the Pacific Ocean. As air moves over the ocean it picks up evaporating water. Soon after this moist air reaches the mainland, it runs into mountain ranges. To get past the mountains, the air has to go over them. This cools the air, and a lot of the moisture in the air condenses and falls as rain on the windward side of the mountain range (windward means the side the wind is coming from). The air that gets over the mountains is very dry, and it usually causes dry conditions and even deserts on the leeward side of the mountains (leeward means the side away from the wind). Thus we have a lush temperate rain forest on the coast of Washington and Oregon, and farther inland on the other side of the mountains there are very dry conditions, almost like a desert.
Wind Wind – the movement of air – is responsible for the redistribution of heat and moisture in the atmosphere, so it has an effect on climate also. Surface winds between the equator and 30 degrees latitude flow towards the equator. In the temperate zone (30 to 60 degrees) surface winds flow away from the equator. And in the polar zones they flow towards the equator again. If this were the only factor affecting wind direction, most parts of the world would have northerly or southerly winds most of the time. There is another important force that alters the patterns caused by convection currents. It is called the Coriolis effect and it is caused by the earth's rotation acting on the northerly and southerly winds. It causes surface winds going south to be deflected slightly to the west, and surface winds going north to be deflected towards the east.
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b. Soil Characteristics You may be wondering why soil has anything to do with the distribution of animals. The effect is indirect: plant species only grow in areas where both climate and soil conditions are appropriate. Because animals need plants for food and sometimes shelter, animal distribution depends on plant distribution. So both plants and animals are affected by soil conditions.
Nutrients Nutrients are materials used for growth and maintenance in living things. In terrestrial systems, plants get their nutrients from soil, and animals get their nutrients from plants. The major nutrients that plants require from the soil are nitrogen, phosphorus and potassium (they get other chemicals such as carbon and oxygen from the air). Plants also need several trace minerals such as calcium, iron, magnesium, etc. The nutrient content of soil depends largely on the mineral content of the rocks it is made from (limestone, granite, basalt, etc.). Some types of rock have very high or low levels of some minerals, so soil based on them might be deficient in one or more nutrients. This in turn would limit the types of plants that could survive in that soil. Most nutrients from the soil that are taken up and used by plants eventually end up being returned to the soil by decomposition after the plant (or the animal that ate it) dies. Sometimes the return of nutrients to the soil is sped up by fire (Episode 3). You will learn about the carbon, nitrogen, and phosphorus cycles later in the course.
Particle Size and Shape The mineral component of soil comes in different sizes and shapes. Sand consists of large rounded particles. It drains well but does not hold water. So after a rainfall, the soil dries very quickly. Clay is made of small flat flakes. Because of the way these particles fit together, clay soils do not drain well, but they do hold water. Silt is very small, fine particles and has a moderate ability to drain and also to hold water. Many regions of the earth have soils that are various combinations of sand, clay and silt. Some regions have predominantly one or another of these particle types. Many plants are adapted to a specific type of soil because of its drainage and water holding characteristics in addition to its nutrient content.
Organic Content The organic material of soil consists of dead plants and animals and animal feces in various stages of decomposition. Organic material in the soil serves as an additional source of nutrients for plants, and also adds to the water-holding capacity of the soil.
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that live in the oceans) are also affected by currents and tides. Most of these factors will be discussed in detail in episodes 8, 9, 10, and 11. Whether they are terrestrial or aquatic, the presence of certain chemicals can be a real challenge for organisms. For example, many plants cannot live in a soil that has a high salt content. Many animals cannot live in salt water.
C. Historical or Evolutionary Biogeography Physical factors are not the only things that affect the distribution of species on the earth. The location of the continents and how they were connected to each other has affected the distribution of species both on the land and in the oceans. To get some background, we need to look at the mechanisms that have been changing the location and connections of the land masses and oceans. 1. Plate Tectonics and Continental Drift a. The crust of the earth is not one solid mass, but is divided into sections called "plates". The crust sits on the mantle, which is made of molten (liquid) rock. The crust is much cooler than the mantle, so the molten rock that is next to the crust cools down and sinks down into the mantle. At the same time but in different places, hot molten rock from lower regions of the mantle rises towards the crust. If it cannot go through the crust, it is forced to flow underneath the crust and creates currents. Friction between the mantle and the crust moves the continental plates in the direction of these currents. This movement is called continental drift. You can see a simulation of this process at: or http://www.pbslearningmedia.org/resource/ess05.sci.ess.earthsys.shake/mountai n-maker-earth-shaker/ or http://www.scotese.com/newpage13.htm (“Continental Drift Animations”) b. The continents move as a result of plate tectonics. Where two plates are moving towards each other, either one dips below the other (subduction), or they collide, pushing upwards to form mountains. Subduction usually is accompanied by volcanic activity. In areas where two plates are moving apart, magma rises through the rift and solidifies, adding new crust. Over millions of years, continental drift has caused 1) land masses and oceans to separate and rejoin, 2) mountain ranges to be formed and 3) volcanic islands to be formed. These processes will be described in more detail in episode 1. c. About 250 million years ago (MYA), the earth's land masses were all stuck together in a supercontinent called Pangaea. Continental drift split and rejoined the land masses several times over those 250 million years. The series of boxes below shows the approximate sequence of events that separated them: © Speer, Maxim and Strong
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Laurasia North America North America
Gondwana
Eurasia
India
Eurasia
South America/Africa South Africa America
Antarctica/Australia Antarctica Australia
India eventually moved north and joined with Eurasia. It is still pushing against the Eurasian continent, forming the Himalayan Mountains. Africa and South America were split apart and are still being pushed away from each other by the Mid-Atlantic Ridge. You will learn more about these events in episode 1. 2. Species Distribution If evolutionary history were not a factor in the distribution of species, then we would expect to find each species everywhere there is appropriate habitat. For example, there is penguin habitat in the Northern Hemisphere, but no penguins occur there naturally. There is sloth habitat in Africa, but no sloths (they are found in South America). The reason for this is that a species is found in an area because it either (1) evolved in that area or (2) dispersed to that area. Current species distribution is the result of evolution and dispersal on land masses and oceans that have been periodically separated and rejoined throughout Earth’s history. Although this is a big topic, you only need to know a couple of facts about it to understand the material in this course: a. Closely related species that are found on different continents are usually there because those land masses were joined at some point in the past. As one species is broken into separate populations (such as being on different continents when the land masses separate), each population begins to change in different ways. If there is enough change, the populations will become new species. This is the basic concept of speciation by which most species are produced. b. Isolated land masses often contain many unique species. c. Species that depend on each other occur in the same areas. In some cases this is because of a symbiotic relationship. In other cases it may be because one species needs the other species for food or shelter.
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III. Evolution and Natural Selection A. Evolution Simply put, evolution means genetic change in a group of organisms over time. Evolution does not happen to an individual; evolution takes place in a group of individuals (a population). There are different ways in which these genetic changes can occur but the most important of these is a mechanism called natural selection. B. Darwin and Natural Selection The theory of natural selection was proposed by Charles Darwin. He did NOT develop the idea of evolution; he did develop the first generally accepted mechanism to explain how evolution could take place. Darwin suggested that organisms had many more offspring than actually survived to reproduce. Therefore, there was a “struggle for survival” among various individuals. He proposed that certain conditions existed in an environment that favored the survival of certain individuals more than others. In other words, some individuals have characteristics that are “better suited” for the environment than others. If these characteristics could be passed on to their offspring, then the offspring that received these “better” traits might also have a better chance to survive and reproduce. Over time, there are more and more members of the population with these “better” traits. Notice that it is not enough just to have “better traits”. Those traits must be passed on to offspring. Survival of the fittest means survival of those organisms that have the most offspring that in turn go on to reproduce. This concept is often misunderstood; it does not mean survival of the strongest, fastest or “best” organisms. Let’s look at a very simple example: mice that live in White Sands, New Mexico, a habitat with white sand dunes and little vegetation. Assume that these mice come in three colors: black, gray and white. As the mice go about their daily business, predators have a very easy time picking out the black mice on a white background. The gray mice are also relatively easy to spot. Predators have more difficulty in spotting the white mice on the white sands. Over time, the majority of the mice who survive and live long enough to reproduce are white – so most of the offspring are white (who in turn must live long enough to reproduce and pass their white genes on to their offspring, and so on). Does this mean that “white coat color” is automatically a better color for a mouse? Not if the mouse lives in a prairie or a forest or on a lava bed. In those places, a white mouse is a “fast food lunch” for a predator – quick and easy to find. Due to natural selection favoring white coats over black or gray coats, the genetic makeup of the group has changed. Hence, evolution has occurred. So, from an evolutionary standpoint, what is more important? Survival or reproduction? Think about this from the standpoint of passing your genes on to the next generation? From an evolutionary point of view, reproduction is more important.
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IV. Evolutionary Adaptation A. What is an adaptation? An adaptation is any trait that allows an organism to be successful (to survive and reproduce in) a given environment. These traits might be physical traits such as thick fur, large flowers, good eyesight, or the presence of antifreeze in the body fluids. They might also be behavioral traits such as hunting techniques (for predators) or evasion techniques (for prey). Interactions with other species can also be adaptations if they improve the evolutionary success of a species. As an example, cushion plants (in the genus Saxifraga) live in cold environments, such as mountain peaks or tundra. They have several adaptations to cold conditions, including: (1) the plant has a small body which hugs the ground, thus avoiding the harsh winds, (2) the plant roots in protected rock crevices, (3) it is dormant through the long winter months and thus grows very slowly, (4) it flowers very quickly once the snow is gone, and (5) it also produces new plants by growing runners from the original plant. Many people are confused about the concept of adaptation. A plant or animal does not decide to adapt to certain conditions. Adaptation is NOT a matter of choice. The organism either has the ability to survive under certain conditions or it does not. If it does not, the plant or animal either dies or leaves. For example, if the climate changes and becomes extremely cold, some plants cannot survive the new conditions. As they die out, only the plants that can tolerate the cold will be able to grow and reproduce, passing on their "cold-tolerant" traits to their offspring. The "cold-tolerant" plants are thus described as being adapted to the environmental condition of extreme cold. B. Where do adaptations come from? Adaptations are traits that organisms inherit from their parents. They are NOT physical characteristics that are acquired after birth. They are also NOT a matter of choice--an organism is either born with these traits or without them. C. Why are certain traits inherited? Individuals of a species generally produce more offspring than are needed to replace the parents. For example, if a pair of birds have five babies, there are three more offspring than needed to replace the parents once they die. And, if those same parent birds have five more babies next year, now they have had 8 extra babies. But most of those offspring will probably die before they have a chance to reproduce. After all, predators have to eat and feed their babies. In general, the offspring that do survive are the ones that are best able to survive in the particular environment in which they live, and are also able to reproduce successfully. Reproduction passes the adaptations to new generations of the same species. This is natural selection in action. © Speer, Maxim and Strong
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V. Taxonomic Classification/Scientific Nomenclature Taxonomy is the process of identifying and classifying species. It is used to group similar organisms based on shared characteristics, which become more specific as the groups get smaller. It assumes that similar organisms have properties in common and that similar organisms are closely related to each other. This way of organizing life is useful because if we know something about one member of a group, we should be able to apply that knowledge to other members of the same group. There are definite levels of categories. The following scheme begins with the largest category (grouped together based on very broad characteristics) and goes toward the smallest category (based on very specific characteristics). We will use the fox squirrel to illustrate. Levels of Taxonomic Classification Kingdom: Animalia Phylum:
Chordata
Class:
Mammalia Order:
Rodentia Family:
Sciuridae
Genus:
Sciurus
Species:
Sciurus niger
Each species has its own scientific name. The name is made of two Latin words. Using this example, all fox squirrels have the scientific name of Sciurus niger. All gray squirrels have the scientific name of Sciurus carolinensis. Since fox squirrels and gray squirrels are members of the same genus, they are thought to be closely related. Since the second word is different, (Sciurus niger versus Sciurus carolinensis), this tells us that these squirrels are classified into two different species. Scientific names should be underlined when hand-written or written in italics when printed. This tradition allows a person to quickly recognize a scientific name, even if s/he has never seen it before. This also means that other levels of taxonomic classification are not underlined or italicized. Example:
The name of our species written out by hand:
Homo sapiens
The name of our species on a printed page:
Homo sapiens
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2. Definition of Species There are a number of different definitions of species in biology. That is partly due to the difficulty of finding a definition that works for the huge diversity of life on this planet. Since the main organisms covered in this course are plants and animals, we are going to use the biological species concept that applies to organisms that reproduce sexually. Using this definition, the word species means a collection of similar organisms that are capable of interbreeding under natural conditions and producing live, fertile offspring. Notice there are two parts to this definition. First, the members of a species can interbreed and will interbreed in the wild. Secondly, live and healthy offspring can be produced, which in turn are capable of having offspring. Let’s go back to the example of the familiar fox squirrel (Sciurus niger). Fox squirrels can breed with each other but do not breed with gray squirrels (Sciurus carolinensis). Since fox squirrels and gray squirrels will not mate together, they are considered to be two different species.
VI. Ecology Ecology is the study of relationships between organisms and their environment or surroundings. The environment itself has been described already under Physical Biogeography. But there is another way to look at ecology--these relationships can be studied at different levels: Population - a group of individuals (of the same species) found in one geographic area. For example, all of the blue catfish found in Town Lake would represent a population. Community - composed of all living organisms found in one geographic area. For example, all of the fish, plankton, plants, algae, turtles and other organisms in Town Lake would be a community. Often scientists study just part of the group of organisms that are found in a specific area. For example, they may just look at the plants, in which case they are studying the plant community. They may just look at the insects, in which case they are studying the insect community. Ecosystem - all living organisms plus all physical characteristics of the environment (precipitation, climate, temperature, etc.) found in a geographic area. The Sahara Desert is an example of an ecosystem. Once again, scientists may focus on particular aspects of the ecosystem instead of trying to look at the entirety. They might just look at nitrogen cycling or energy flow through the ecosystem. They might focus just on soil characteristics and soil organisms, in which case they are studying the soil ecosystem. As you go through Living Planet videos, you will notice that the focus shifts between populations, communities and ecosystems. When Attenborough is discussing the © Speer, Maxim and Strong
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adaptations of creosote bushes that allow them to live in hot deserts, he is discussing ecology at the population level. When Attenborough discusses the forests of England and the various plants and animals found there, he is discussing ecology at the community level. When Attenborough is discussing the effects of waves and tides on the organisms found on rocky shores, he is discussing ecology at the ecosystem level.
VII. Metric System Measurements and distances in the videos are given in both metric and English units. When Attenborough is discussing the changes that occur in the Himalaya Mountains around 1000 meters, you can use the conversion tables to translate that into feet (about 3280 feet) Here are some of the conversion factors: 1 mile = 1.6 kilometer 1 mile = 5,280 feet 1 inch = 2.54 centimeters 1 kilogram = 2.2 pounds 1 pound = .454 kilograms
1 kilometer = 0.6 miles 1 kilometer = 1,000 meters 1 meter = 39.4 inches or 3.28 feet 1 meter = 100 centimeters 1 meter = 1,000 millimeters
References Campbell, Neil A and Jane B. Reece. Biology, 6th ed. Benjamin Cummings, 2002. Cox, C. Barry and Peter D. Moore. Biogeography, an ecological and evolutionary approach, 5/e. Blackwell Science, 1993.
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CONCEPTS STUDY QUESTIONS FOR INTRODUCTION: 1.
Look at the following map of the world and answer the questions below.
a. Fill in the three labels on the left side of the map. b. The numbers at the base of the map represent ___________________. (Choose between latitude and longitude.) c. The numbers on the right side of the map represent ___________________. (Choose between latitude and longitude.) d. The spot marked “X” is located at approximately _________ latitude and _________ longitude. (Don’t forget to include N, S, E, or W.)
2.
What is the difference between latitude and longitude?
3.
What is the difference between the earth’s revolution and the earth’s rotation?
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4.
What is the difference between an ocean and a sea?
5.
Define and describe the concept of a species tolerance zone. Differentiate between the optimal range, stress zones, tolerance limits and lethal zones.
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6.
Define limiting factor. Compare and contrast the limiting factor of terrestrial organisms with those of aquatic organisms.
7.
Compare and contrast biotic and abiotic factors. Give examples.
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8.
Compare and contrast producers, herbivores, predators and decomposers. Give examples.
9.
Explain the two main components of climate that influence species distribution. Explain how they vary with latitude and altitude.
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Discuss the effect of ocean currents on climate.
11.
Describe a rain shadow and its effects upon precipitation.
12.
What is the role of wind in climate?
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13.
Why are soil characteristics important in determining the distribution of animals?
14.
Discuss the roles nutrients, particle size and shape, and organic content play in determining soil characteristics.
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15.
Describe plate tectonics and continental drift.
16.
What effects have plate tectonics and continental drift had on the distribution of species?
17.
Which modern continents were part of: a. Pangaea
b. Laurasia
c. Gondwana
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Describe the concepts of evolution and natural selection.
19.
Describe the concept of evolutionary adaptation.
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20.
Define taxonomy and briefly explain why it is important.
21.
List the levels of taxonomic classification in correct order from largest to smallest.
22.
Define species, using the biological species concept. Give examples.
23.
What is ecology?
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Compare and contrast populations, communities and ecosystems.
25.
Be familiar with the portion of the metric system listed in the introduction.
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LIVING PLANET EPISODE 1 MATERIAL FOR YOU TO COVER Read the CONCEPTS section in the study guide for episode 1. Answer the Concepts Study Questions. Watch Video Episode 1 – The Building of the Earth. Answer the Video Study Questions.
EPISODE 1 LEARNING OBJECTIVES To become acquainted with: 1. Symbiosis 2. Characteristics of life 3. Ecology of mountains: location, climate, characteristics, zonation, life forms and adaptations 4. Volcanic activity 5. Colonization process that occurs after volcanic eruptions 6. Succession 7. Ecology of deep sea vents: locations, characteristics, life forms and adaptations 8. Ecology of hot springs: locations, characteristics, life forms and adaptations
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CONCEPTS FOR EPISODE 1: THE BUILDING OF THE EARTH MOUNTAINS AND ZONATION One noticeable characteristic of mountains is the presence of distinct life zones. As you start at the bottom of a mountain and go towards the top, you move through different layers, each with its own particular group of plants and animals. What causes zonation? The principle factor is temperature. As you increase altitude, the temperature becomes colder. Plants that live on the top of tall mountains must be able to withstand more cold than plants that live at the bottom. As the plant community changes, the animal community changes as well, since animals rely upon plants for their food. As the temperature drops, the amount of snow and ice increases. Latitude also has an effect on zonation. If you compare a mountain in the tropics to a mountain in Colorado, you will have to go to higher altitudes in the tropics to reach the same conditions of cold. As a result, the comparable life zones are found at different altitudes. The following tables show the influence of latitude on life zones. TABLE 1: UPPER LIMIT OF TIMBERLINE. This shows the average altitude (in meters) at which trees CANNOT grow. Mountain Mt. Kilimanjaro Mt. Etna Ural Mountains
Location equatorial Africa Italy Russia
Upper Limit of Timberline 3,000 meters 2,200 meters 1,100 meters
(Reference: Ricciuti, E. R. 1979. Wildlife of the Mountains. Harry N. Abrams, Inc., NY.)
TABLE 2: ALPINE ZONE FOR DIFFERENT MOUNTAINS. This shows the average altitudes (in meters) at which the alpine zone is found.
Mountain Name Western Alps, Europe Central Rockies, North America Eastern Himalayas, Asia Mount Kenya, Africa
Altitudes for Alpine Zone 2000 to 2800 meters 2600 to 3100 meters 4400 to 5500 meters 3300 to 4200 meters
(Reference: Ricciuti, E. R. 1979. Wildlife of the Mountains. Harry N. Abrams, Inc., NY.)
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Other physical factors affect zonation. Wind can have a major impact upon plant life. Generally, winds are stronger at higher altitudes. Plants that live on high mountain peaks are buffeted by strong winds, especially when they are not insulated by snow. These plants generally are small and hug the ground, which exposes less of the plant body to the wind. In the northern hemisphere, southern-facing slopes are generally sunnier, warmer and drier than northern-facing slopes. Other factors - loose soil, volcanic rubble, avalanches - can also affect vegetation.
Zonation in the Himalayas In the tape, Attenborough begins in the deep valley and climbs upward towards the mountain peaks. He describes five distinct life zones, which are further explained below. The altitudes given are average altitudes. (1) lower reaches of the deep valley. The climate is warm, humid and tropical. There is lush vegetation of many species, including bamboo and many rhododendron trees. Animals are numerous, including tigers, rhinoceros and many birds. Watch the tape for descriptions of the animals found here: langur monkeys, ring-necked parakeets and pheasants. (2) 1000 meters - rhododendron trees dominate. The air is still moist but the temperature is cooler, with many warm days and cold nights. Night frosts are common. Watch the tape for descriptions of the organisms found in the cooler forests: orchids, moss, closepacked flowering plants, Himalayan panda, musk deer. (3) 2500 to 3300 meters - coniferous forests of Himalayan fir and Bhutan pines. Animals on the tape include yellow-throated marten, Himalayan bear, ants, insects and rodents. (4) 3300 to 4400 meters - shrubs, grasses and small cushioned flowering plants. Watch the tape for the animals who live here - bearded vultures, snowcocks, tahrs and choughs. (5) 4400 to 5400 meters - lichens. Above this altitude (5400 meters), there is no vegetation. The ground is covered with snow and ice.
LICHENS AND SYMBIOSIS The meaning of symbiosis may be somewhat vague but it is still useful. Commonly, symbiosis refers to a very close relationship between two different organisms. In fact, the word "symbiosis" translates into "living together." Most ecologists use symbiosis to represent a relationship which (1) is required by at least one partner in order to survive or reproduce and (2) benefits at least one partner.
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Symbiosis is a broad ecological term (often abused and misused) that refers to organisms living in close association with one another. There are different kinds of symbiosis: mutualism, commensalism and parasitism. In mutualism, both partners benefit from the relationship. In commensalism, one partner benefits and the other gets no apparent benefit nor is harmed. In parasitism, one partner (the parasite) benefits from the relationship while the other (the host) is harmed. So what is the problem with clearly defining symbiosis? Symbiotic relationships are not always simple and straightforward. Some appear obvious. The termite cannot digest the cellulose in wood. The termite must have living one-celled organisms called flagellates in its gut to digest cellulose. The termite provides the flagellates with wood; the flagellates provide the termites with food. Seems like a clear-cut relationship, doesn't it? Further study has shown that the flagellates contain bacteria inside their bodies; it is the bacteria inside the flagellate that actually digest the cellulose. So, this is a mutualistic relationship between three species: termites, flagellates and bacteria. Everybody wins. Not all relationships fit the definition of only one category of symbiosis. Understand that these categories are our attempt to make sense of what we observe in the natural world. Nature does not necessarily fit into our categories. A case in point is the symbiotic relationship found in lichens. For many years, lichens were the "classic" example of mutualism. A lichen is formed by an association between one kind of algae and one fungus. Traditionally, it was felt that both organisms benefited from the relationship. The algae provide food by photosynthesis; the fungus provides nutrients, through decomposition, which the algae need for growth. Lichens are usually considered to be an example of mutualism. However, this is not always so clear-cut. Under some situations, the fungus eats the algae. When this occurs, the relationship then becomes parasitic. There are other factors to consider. The algae can live without the fungus; the fungus cannot live without the algae. However, the combination of the fungus plus the algae forms a totally different "organism" (the lichen) with characteristics that are different from either partner. Many species of algae and fungi form these relationships and they are so specific that particular lichens are considered to be lichen species, each with its own specific shape, color and preference of substrate (type of rock, wood, etc.) So, what is a lichen? Is it mutualistic or parasitic? Well, a lichen can be mutualistic at one time and parasitic at another time. Complex relationships found in nature can be very difficult to categorize. Lichens are very important organisms in many ecosystems. Since the fungus can break down bare surfaces, such as rock or wood, the lichen is able to colonize surfaces that other organisms cannot. The algae provide the food while the lichen breaks down the substrate. As a result, the surface is changed, often providing opportunities for plants to move into the area. © Speer, Maxim and Strong
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In very harsh environments, such as mountain peaks, polar regions and bare rock surfaces, lichens become very important sources of food. Reindeer moss (which is a type of lichen) is even able to grow on the soils of tundra and northern coniferous forests. As you watch episodes 1 and 2, pay attention to the animals that eat lichens. Lichens are able to absorb nutrients that are dissolved in rain and dew. Because of this, lichens are very sensitive to air pollution, especially heavy metals and acid rain. Lichens can thus be used as an indirect measure of some types of air quality. Look around Austin. Do you see lichens? What does that tell you about air quality in Austin? If lichens begin to disappear, what will that indicate?
HYDROTHERMAL VENTS Hydrothermal vents were first discovered in 1977 by scientists examining the volcanic ridges of the Pacific Ocean floor, near the Galápagos Islands. These hydrothermal vents are deep-sea springs that release water that has been heated to very high temperatures by underwater volcanoes. In the process, the heated water picks up large amounts of sulfides. When it comes out of the hydrothermal vent, the sulfides are released into the cold deep-sea waters. Living near the hydrothermal vents is an entire community of organisms that take advantage of the sulfide-rich waters. The sulfides are used by chemosynthetic bacteria that use the energy from sulfides to produce their own food. Giant tube worms contain bacteria in their tissues, apparently living in a symbiotic relationship. The tube worm receives food from the bacteria living in its body. In exchange, the tube worm concentrates sulfides in its blood, which are then delivered to the bacteria for processing. Other organisms - mussels, giant clams and polychaete worms - filter bacteria from the water. For a while, it was thought that this was the only system on earth that did not rely upon sunlight for energy. Since then, other enclosed ecosystems (such as caves) have been discovered that are also based on chemosynthetic bacteria. Website for hydrothermal vents: http://www.pmel.noaa.gov/vents/nemo/explorer/concepts/hydrothermal.html Reference for hydrothermal vents: Smith, Robert Leo. 1992. Elements of Ecology, 3rd edition. HarperCollins, NY. Reference for cave ecosystem: Discover, January 1997.
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CONCEPTS STUDY QUESTIONS FOR EPISODE 1: 1. Describe the factors that affect zonation in mountains
2. Define symbiosis and state the two criteria used by ecologists to determine whether or not a relationship is symbiotic.
3. Define and compare the three different kinds of symbiotic relationship described in the CONCEPTS.
4. Describe the relationship between termites, flagellates and bacteria, including the benefit to each species in the relationship.
5. Describe the organisms that form lichens and the relationship between them.
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6. Explain why it is difficult to decide whether lichens represent mutualism or parasitism.
7. Describe why lichens are sensitive to air pollution.
8. Describe a hydrothermal vent.
9. The energy that supports the organisms living near a hydrothermal vent comes from ______________. 10. What kind of bacteria can use the energy in sulfides to produce their own food?
11. Describe the relationship between chemosynthetic bacteria and giant tube worms.
12. Describe the relationship between chemosynthetic bacteria and mussels, giant clams and polychaete worms.
13. Where, besides hydrothermal vents, have chemosynthetic bacteria been found?
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VIDEO STUDY QUESTIONS FOR EPISODE 1: 1. In what way is the Earth unique?
2. What are the two essential requirements for life? Where is life most abundant on Earth?
3. How much of the Earth's surface is covered with water? Where did life begin?
Locator: Himalayas 4. Describe the location of the deep valley through which the Kali Gandaki River flows.
5. Describe the vegetation that is found in the deep valley. What is the climate? Why do the rhododendrons produce blossoms?
6. Describe the animal life found in the deep valleys: a. langur monkeys
b. ring-necked parakeet
c. blood pheasant
d. tragopan pheasant (the male pheasant is called the cock and the female is called the hen)
e. impeyanus pheasant
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7. Be able to describe the changes that occur in the climate, vegetation and animal life as one moves from the valley to the highest peaks. (Be able to identify the 5 life zones.)
Locator: "As you walk higher..." [Note - about 1000 meters altitude] 8. What changes take place in the rhododendron forest? What other plant life is found here? What adaptation is seen in the flowering plants?
9. Describe the animals that are found in the cooler rhododendron forests. What adaptations are seen in these animals? What is their diet? a. Himalayan panda
b. Musk deer
c. griffon vultures
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10. How does the physical environment affect the animals and plants that live in that environment? How does the vegetation influence the animal life?
Locator: Fir Forests [Note - about 2500 meters] 11. What type of trees are found in this forest? What physical factor is responsible for the lack of rhododendrons?
12. Describe the following animals and their adaptations to life in the fir forests. What is their diet? a. yellow throated marten
b. Himalayan bear
Locator: 10,000 feet [about 3000 meters] 13. What is happening to the fir forest? What is different about the climate?
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14. What is unusual about the Kali Gandaki River?
Locator: Village 15. Describe the following animals that are found at high altitudes. What do they eat? [Note altitude is about 3500 meters] a. lammergeier or bearded vulture
b. snowcock
c. tahr
d. red-billed chough
e. yellow-billed chough
Locator: "Higher still...."
[Note: about 4500 meters]
16. What type of organism can grow at very high altitudes? How long is the growing season?
17. As the altitude increases, what happens to the vegetation?
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18. What other mammal (besides man) can live at very high altitudes? What adaptations are seen in animals and humans who live at very high altitudes?
======================================================================= ADDITIONAL INFO: In his book, Attenborough also explains that chests and lungs are larger in highland people. Even with these changes, humans have not fully adapted to very high altitudes. Above 6000 meters, women cannot have children, according to Attenborough. The problem is providing sufficient oxygen to the developing young. (p. 18) ======================================================================= 19. How old are the Himalayas? When were they formed? What evidence shows that they were once at the bottom of the sea?
Locator: Iceland 20. What is basalt? How is it formed?
21. How are basalt columns, such as those found in the Hebrides, formed?
Locator: Africa 22. How are lava lakes formed?
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Locator: Icelandic Volcano 23. How are volcanic islands formed?
24. Describe the ridge found on the Atlantic floor. [Note: this is called the Mid-Atlantic Ridge.]
25. Explain how the continents of Africa and South America were separated.
26. Describe the events happening to the plate that forms the eastern part of the Pacific ocean floor. Describe the trench formed at the western edge of North America. What is different about volcanic activity as a result of the trench?
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Locator: Mount St. Helens 27. What was the impact of the volcanic eruption that occurred on May 18, 1980 at Mount St Helens?
Locator: "On the opposite side of the Pacific" 28. Describe the volcanic eruptions that occurred when a volcano erupted on Krakatau on August 27, 1883.
29. What was the impact of this eruption upon the climatic conditions of the earth?
30. Describe the changes that have occurred since the initial eruption, including the formation of Anak.
31. What are volcanic fumes composed of?
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Locator: Underwater Volcanoes [deep sea springs or hydrothermal vents] 32. What happens to sulphurous fumes when volcanoes erupt on the ocean floor?
33. Describe the organisms that draw their energy from underwater volcanoes.
34. What is unusual about this group of organisms?
Locator: Hot Springs, New Zealand 35. How are hot springs formed? How is boiling mud produced?
Locator: Hot Springs, Yellowstone Park 36. Describe the algae mats and the community that develops on the algae mats. (grubs are insect larvae)
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37. How are the algae mats and their residents destroyed?
Locator: Rift Valley, Africa 38. What is the primary animal that harvests the single cell algae found in the hot spring lakes in the Rift Valley? How many tons of algae are harvested each day?
Locator: Basalt Lava Flow 39. How are basalt lava flows eventually colonized by plants?
40. Describe lava tunnels (actually called lava tubes). How are they formed? Describe the vegetation and animals that are found in the lava tubes. How have these animals adapted to the conditions of the lave tubes?
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Locator: Mount St. Helens 41. Why is the colonization of volcanic ash difficult for plants?
42. Describe the appearance of Mount St. Helens in 1982.
======================================================================= ADDITIONAL INFO: Within a short period of time, plants began the colonization period. As Attenborough explains in his book (pg 36), one flowering plant, the fire-weed, regularly colonizes volcanic ash. As fire-weed and other herbaceous plants took hold, the conditions of the ash changed. As the plants bloomed and died, their decomposing bodies provided nutrients for other plants, such as shrubs, to move into the area and become established. Within 5 years, dogwoods, blackberries and blueberries had colonized the slopes. Over time, trees may replace the shrubs and flowering plants, thus replacing the original forests that were destroyed. This illustrates the ecological concept of succession. Succession refers to change in community structure over time. The first plants to move into an area are usually called pioneer species. As the conditions change, pioneer species are usually replaced by other plants that can now grow in the "changed" conditions. As new plants move in, the environment continues to change. Often, this continues until the climax community moves in. The climax community is a mixture of plants that will grow and be replaced by their own offspring, as opposed to other types of plants. Once the climax community is established, succession is over ... until a disturbance (such as fire or drought or hurricane or volcanic eruption) occurs. Check out information about the recovery of this area after 30 years at: http://www.fs.fed.us/pnw/pubs/science-update-19.pdf Check out this NOVA video: https://www.youtube.com/watch?v=KlbnLnHSRzE Question from the video: Name one pioneer plant from Mount St. Helens.
Concept questions from this additional information: 1. What is succession?
2. What are pioneer species?
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Locator: Krakatau's Child (Identified as Anak earlier in the tape) 43. Describe the conditions of Anak. What plants have colonized this relatively new island? (the name of the tree is casuarina)
Locator: Rakata (island remnant of Krakatau) 44. Describe the changes in vegetation and animal life that have occurred on Rakata, the remaining island fragment of Krakatau, since the volcanic eruption 100 years ago.
45. Which types of animals are NOT found on Rakata?
Locator: Indian Plate Moving Towards Asia (Return to Himalayas) 46. How did the movement of continental plates create the Himalayas?
47. How fast is the Indian plate still moving north into Asia?
48. Are the Himalayas growing, shrinking or staying the same?
49. How was the valley formed by the Kali Gandaki River?
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LIVING PLANET EPISODE 2 MATERIAL FOR YOU TO COVER Read the CONCEPTS section in the study guide for episode 2. Answer the Concepts Study Questions. Watch Video Episode 2 – The Frozen World. Answer the Video Study Questions.
EPISODE 2 LEARNING OBJECTIVES To become acquainted with: 1. Where the cold regions of the earth are located 2. Problems of living in cold climates 3. Adaptations of life forms that live in cold climates 4. Typical life forms that live in cold climates 5. Relationship between body shape, size and cold 6. Ecology of Antarctica: location, climate, characteristics, life forms and adaptations 7. Ecology of the Arctic: location, climate, characteristics, life forms and adaptations 8. Differences between Antarctica and the Arctic 9. Tundra ecology: location, climate, characteristics, life forms and adaptations
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CONCEPTS FOR EPISODE 2: THE FROZEN WORLD COLD AND WINDY PLACES ON EARTH There are three regions of the Earth that experience extremely cold and windy conditions. These are (1) high mountain peaks, (2) polar regions, and (3) tundra. Polar regions are areas where surface ice and snow remain frozen year round. There are two polar regions: Antarctica and the Arctic Ocean. Antarctica is the huge polar continent of the Southern Hemisphere. It is surrounded by a permanent ice pack and the land is permanently buried by a mile or so of glacier ice. The Arctic Ocean is the ocean that covers the North Pole, which has a permanent ice pack on its surface. Tundra is found in areas where the climate is warm enough in summer to melt surface ice and snow and thaw a few inches of the soil. A permanently frozen layer (the permafrost) is located beneath the surface of the soil in arctic regions. Arctic tundra occurs on the northernmost lands of North America and Eurasia. Between the arctic tundra and the North Pole is the frozen pack ice described above. Alpine tundra occurs high on mountains, but not necessarily on top of the mountain. On the tops of very high mountains the snow never melts and the soil, if there is any, never thaws. Tundra only refers to areas where the surface soil thaws briefly in the summer All three regions experience intense cold and high winds. The polar and arctic tundra regions experience long periods of darkness as well. The earth's axis points toward the sun in the summer and away from the sun in the winter. During the winter, within 30 degrees of the pole, there is complete darkness for several months. The polar regions were not always cold. 140 million years ago, the polar regions were warmer because the continents were located in different positions. This allowed the ocean currents to bring warm water all the way to the poles, preventing the water there from freezing. At that time, the continent of Antarctica wasn't at the South Pole, either. It was part of a supercontinent called Gondwana, along with South America, Africa, Australia and New Zealand. Gondwana was located close to the equator. Then the continents split apart and drifted away from each other. Antarctica moved to its present position over the South Ppole, cutting off the flow of warm ocean currents, freezing the oceans around the continent and creating the intensely cold, windy conditions that exist there today. PROBLEMS THAT FACE ORGANISMS THAT LIVE IN COLD PLACES Two main problems face organisms living in extremely cold places. First, extreme cold kills cells. When the liquid water inside a cell freezes and ice crystals form, the cell membrane and/or cell walls rupture as the ice crystals expand, killing the cells. The second main problem is extreme cold also slows down vital biochemical reactions. The rate at which chemical reactions occur is dependent on temperature. © Speer, Maxim and Strong
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This rule applies not only to simple chemical reactions in a chemistry laboratory, but also to the complex biochemical reactions that occur inside living organisms. Up to a certain point, the higher the temperature, the faster a chemical reaction will run. Applied in reverse, the lower the temperature, the slower the chemical reactions, which can be a serious problem to living things. TEMPERATURE REGULATION IN ANIMALS Animals have to regulate their body temperatures in order to keep those biochemical reactions going at a proper rate to maintain life. This is a big problem for animals that live in cold places because their chemical reactions can get too slow. On the other hand, temperature regulation is also important in temperate areas that get cool at night and hot during the day. You will see temperature regulation discussed in many of the subsequent episodes. For now, we are going to focus on the problem of cold. There are two main strategies for regulating body temperature used by animals. Some animals are ectotherms and other animals are endotherms. Ectotherms, such as lizards and insects, cannot burn fuel (food) to provide heat to raise their internal body temperature. Their body temperature is determined by the temperature of the environment, so they cannot have body temperatures above environmental temperatures. A cold environment means cold internal body temperature, which slows the rate of chemical reactions. However, don’t make the mistake of thinking that ectotherms do not regulate body temperature. Although they do not burn fuel to raise body temperature, they can raise and lower body temperature through behavior. Let’s look at a typical ectotherm, a lizard. At night, a lizard's body temperature falls and it becomes sluggish as the biochemical reactions that fuel its muscles slow down as environmental temperatures fall. Remember, it cannot burn fuel to allow its metabolism to keep its body warm. During the day, it basks in the sunlight to raise its body temperature to a level at which its biochemical reactions can occur at a rate fast enough that it can become active and hunt for food. If it gets too hot, the lizard moves into the shade to cool down. In extremely cold conditions, the lizard faces two problems. Body temperature becomes so low that its biochemical reactions become extremely slow. Also, its cell membranes would solidify to the point that its nerves would not be able to transmit signals. Without a properly functioning nervous system, the lizard would not be able to regulate important body processes, such as breathing and heart rate. The lizard would die. As a general rule, few ectotherms are found in extremely cold places on land. Endotherms, such as birds and mammals, have a different approach to solving these same problems. They do not rely on the environment to provide their only heat source. They generate their own body heat by burning lots of fuel (food) inside their cells. Notice that endotherms also use behavior to help regulate body temperature, especially when it is hot. You are an endotherm and you move into the sun to warm up and into the shade to cool down. But there is a big difference. At night, you are not © Speer, Maxim and Strong
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sluggish even if it is cold outside. You burn fuel both day and night to maintain a relatively stable body temperature that does not change very much. Because endotherms generate their body heat internally, they can survive cold temperatures without their biochemical reactions slowing down. However, they can only survive if they can find enough food to fuel the furnaces inside their cells. As environmental temperature drops, more heat is lost from the surface of their bodies, and the lost heat must be replaced by eating more food. If they cannot meet the high demands for food, they will begin to cool off. Unlike ectotherms, birds and mammals cannot tolerate large changes in their internal body temperature. Their brains and other organs are fine-tuned to normal body temperature and will not operate properly if the body temperature is a few degrees higher or lower than normal. Thus, only a small amount of cooling will cause these organs to fail in carrying out their usual functions. If these organs fail, the animal dies. ADAPTATIONS TO THE PROBLEMS OF LIVING IN COLD PLACES Animals have evolved a variety of solutions to solve the two main problems of living in cold places: (1) formation of ice crystals in body fluids, and (2) slowing down of biochemical reactions. As you go through the section, notice that some strategies are used by ectotherms and others are used by endotherms. Some are used by both. (1) One solution is adding antifreeze to body fluids. This is one way to prevent ice from forming. Antifreeze lowers the freezing point of water by adding chemicals to the water. For example, automotive antifreeze contains the chemical ethylene glycol which, when added to the water in a car radiator, lowers the freezing point so that the water will not freeze and rupture the radiator. The animals still get very cold, it’s just that their body fluids don’t freeze as readily when they contain some kind of antifreeze. In animals, antifreeze molecules are chemicals that lower the freezing point of the body fluids and prevent ice crystals from forming within the body. For example, the blood of the Antarctic icefish, Trematomus, contains a glycoprotein that is 200-500 times more effective than salt at lowering the freezing point of water. This icefish can survive body temperatures down to -2.6° C. Watch for other examples of animals that use antifreeze in the episode. (Notice, antifreeze is used by ectotherms.) (2) Insulation is another solution to these problems. Endotherms use layers of insulation to form a warm layer of air next to their skin. That way, they don’t lose as much heat to their environment. By trapping heat in this way, the animals do not have to eat as much to replace lost heat. Mammals use fur as insulation. In mammals that live in cold areas, there are two layers of fur. The outer layer consists of guard hairs, usually long and coarse. The inner layer, the undercoat, consists of a thick layer of fine wooly hairs. The undercoat traps air in the spaces between the hairs. Air does not transmit heat very readily, so the trapped air prevents the rapid loss of heat. Mammals that live in extremely cold climates © Speer, Maxim and Strong
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have thicker fur than those that live in less frigid areas. Humans have taken advantage of this in the past by hunting the animals of the Arctic regions for their fur to make insulating layers (coats) for people. All mammals can make their insulating layer thicker by fluffing up their fur. Tiny muscles at the base of each hair contract, pulling the hair more perpendicular to the skin, and making the insulating layer thicker. The fur traps more air, and less heat is lost. Many mammals change the thickness of their insulating layer with the seasons. They grow a thick undercoat as winter approaches, and shed it in the spring, as warmer weather approaches. Look for the following examples of fur as insulation as you watch the episode: the snow leopard, the hyrax, the vicuña and the guanaco, and the fur seal. Birds use feathers as insulation. Again, there are two layers of feathers. The outer layer consists of contour feathers. Contour feathers are smaller versions of the familiar wing feathers. They cover the inner layer of feathers, the down. Down feathers do not have a long quill or vanes like wing and contour feathers do. Instead, they have a short quill with fluffy tufts that excel at trapping air. This establishes an insulating layer of air. Humans have long taken advantage of the insulating properties of down feathers by plucking geese and ducks and using the down in feather pillows, coats, mattresses, etc. Birds can fluff their feathers to increase the thickness of the insulating layer, so on a cold day, they look larger than on a warm day. Look for the sunbirds fluffing up their feathers as you watch the episode. Swimming birds and mammals have more trouble with insulation than land animals, because water is much more efficient at transmitting heat than the air. Thus, birds and mammals that swim tend to have thick insulation layers. Penguins are swimming birds. Their feathers are especially adapted to provide excellent insulation. Long and thin, with tips that point inward towards the body, the contour feathers have tufts at the base that mat together to make a barrier that water cannot penetrate. They also have feathers covering almost their whole bodies, including almost all the way down their legs. Adelie penguins even have feathers on their beaks! Most birds do not have such complete coverage. Another type of insulation is blubber. Blubber is a thick layer of fat underneath the skin that forms a blanket trapping heat within the body. (Like air, it transmits heat less efficiently than water.) The whales are a great example of mammals that use blubber for insulation. Whales have little body hair and rely on blubber for all their insulation as they swim in cold ocean water. Consequently, their blubber layers are very thick. Humans have taken advantage of whale blubber in the past, by using the blubber to produce whale oil which was burned in lamps. Even today, the Inuit (Eskimos) hunt whales and consider the blubber an excellent food. Look for these animals which use blubber as insulation as you watch the episode: the true seals, such as the elephant seal, and the penguins. Be sure to note how their blubber allows the elephant seal to dive to great depths, and why the fur seal must stay in surface waters. Animals are not the only organisms that use insulation to protect themselves from the © Speer, Maxim and Strong
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cold. When you watch the episode, note how the two different species of lobelia use different methods of insulation to protect themselves from freezing temperatures. (3) Body size can also be a solution to the problems of extreme cold. Large animals have a smaller amount of surface relative to their volume than do smaller animals. Thus, they have less surface across which heat can escape, and they lose heat less rapidly to their environment than do small animals. Therefore, animals that live in extremely cold areas are often larger than their relatives that live in milder climates. Look for these examples as you watch the episode: polar bears, king penguins and emperor penguins. (4) The coloration of an organism can help it protect itself from the intense cold. Dark colors such as black or deep brown absorb most of the light that hits them. The light energy is transformed into heat that can be used to warm an animal or plant. Light colors, on the other hand, reflect much of the light that hits them. Look for the following examples of organisms that use dark colors to help them stay warm as you watch the episode: the primitive insects that live at high altitude on mountains; blue-green algae in Antarctica. The color of an organism can also be used for other purposes besides temperature regulation. Many animals use camouflage, in which their coloration matches the background. Animals that hunt use the camouflage to avoid being seen by their prey, and plant-eating animals use camouflage to avoid being eaten by predators. Many mammals and birds that live in snowy places are white to match their white background. Because they generate their own body heat, they do not need dark coloration to help them stay warm. Mammals and birds that live in tundra areas where the snow melts in the summer often change their coloration from white to brown so that they remain camouflaged. Look for the following animals that use coloration for camouflage while you watch the episode: Arctic foxes, polar bears, snowy owls, ptarmigans. Which of these animals change colors with the seasons? Polar bears are well camouflaged by their white coloration. And they use it to ambush seals, as you will see as you watch the episode. But their white coloration is an exception to the rule of white reflecting more light. They look white because their hair is transparent, which allows the sunlight to penetrate their thick fur to their black skin, where light is absorbed and transformed into heat which is used to warm the body. (5) Many animals use a special adaptation called countercurrent exchange to keep from losing too much heat to the cold environment. This adaptation is mainly found in endotherms. Let’s use penguins as an example. Penguins do not have feathers on their feet. Without insulation on their feet, it seems like they should lose a lot of heat through their feet. However, they can stand barefoot on a glacier and not freeze to death because of the arrangement of blood vessels in their legs. Arteries bring warm blood from the body to the feet and veins © Speer, Maxim and Strong
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return cold blood from the feet to the body. As the veins return to the body, they pass close to the arteries. HEAT is transferred from the warm blood in the arteries to the cold blood in the veins, and is carried back into the body instead of being lost to the environment. Why is this countercurrent exchange? First, the blood in the arteries is flowing in the opposite direction of the blood in the veins. That’s the countercurrent part. Then, heat is moving from the arterial blood into the venous blood. That’s the exchange. [PLEASE NOTE: HEAT is transferred, not blood.] Look at the diagram below to see how heat moves out of the blood of the hot artery and into the blood of the cold vein. Notice as the blood in the vein returns towards the body, the blood gets warmer (goes from 9° C to 33° C). As the blood in the artery moves into the foot, the blood gets cooler (goes from 35° C to 10° C). A little bit of heat is still lost where the feet touch the ice but it is only a small amount (2° C) of heat loss to the environment instead of a large amount. And, the penguin’s feet stay warm enough that they don’t freeze!
(6) Hibernation is another method used by animals to deal with extremely cold conditions. When an animal hibernates, it finds a safe place, usually a protected burrow or other hole in the ground, and settles in for the winter. The animal's metabolic rate (the rate at which it burns fuel) decreases and its body temperature drops. By decreasing its metabolic rate, it can avoid eating during a time of the year when food would be very difficult to find. (7) Many of the tundra area residents do not stay there year round. They escape the extreme cold through migration. The winters are too severe, so they migrate towards the equator to less severe climates. You may wonder why they ever go to the tundra at all. They migrate to the tundra areas in the summer to breed because food is very abundant and, because the sun does not set, they can feed all day long. © Speer, Maxim and Strong
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DIFFERENCES BETWEEN ANIMAL COMMUNITIES OF ARCTIC AND ANTARCTIC Even though they are both polar regions, the animal communities of the Arctic and Antarctic regions differ in many ways. In Antarctica, there are no large terrestrial predators. Once animals such as seals and penguins are on the land, they are relatively safe from predators. (However, their young are still vulnerable to flying predators such as the skua, a large predatory seagull which attacks penguin chicks and eggs, or to other members of their species, such as the large bull seals which may trample or attack seal pups.) There are many predators in the water, so Antarctica is not predator-free. Why aren't there any large terrestrial predators in Antarctica? No large terrestrial predators were present on the continent when it split from the rest of Gondwana. Because it is isolated from other continents by the Southern Ocean and because its climate is so harsh, no large terrestrial predators have been able to colonize the area. The Arctic region does have large terrestrial predators such as the polar bear and the Arctic fox. In this area, the large continents of North America, Europe and Asia extend into the Arctic region from warmer regions further south. Large terrestrial predators have been able to move into this area. Thus, the animals that live in the Arctic must have adaptations for defense against these large land-based predators. An example is the guillemots and auks. Although they look and behave much like penguins, they have retained their powers of flight, which they can use to escape from large terrestrial predators. The lack of isolation of the Arctic region also means that land animals such as the caribou can migrate to and from the area. They migrate north in the summer to take advantage of the rich food supply and south in the winter to escape the harshest cold and windy conditions. Many Antarctic animals migrate, too, but they must all be able to swim or fly.
Puffins and Guillemot
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CONCEPTS STUDY QUESTIONS FOR EPISODE 2 1. Describe and compare the two polar regions with respect to types of ice and presence or absence of land.
2. Compare the locations of arctic and alpine tundra.
3. Describe the two main problems for organisms living in extremely cold places.
4. Compare ectotherms and endotherms. Describe the advantages or disadvantages of being an ectotherm or an endotherm living in a cold climate.
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6. Compare the animal life of the Arctic and the Antarctic.
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VIDEO STUDY QUESTIONS FOR EPISODE 2: Locator: Mt. Rainier 1. What is the significance of red snow? How do these organisms produce food? What do they need in order to grow and reproduce?
2. Describe the yearly movements of ladybugs at Mt. Rainier.
3. What do the permanent insect residents use as food?
4. What is unusual about the grylloblattids?
Locator: Mt. McKinley 5. How do the other animal inhabitants, such as the Dahl sheep and ground squirrels, cope with the winter months?
6. What are the problems that face plants that live on steep, high slopes?
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Locator: Himalayas 7. Describe the blue sheep.
8. Describe the snow leopard and its adaptations to life in the cold mountain environment.
Locator: Mountains of Africa 9. At what altitude do you find the giant groundsels and giant lobelias?
10. What conflicting problems do plants that live on Mt. Kilimanjaro and Mt. Kenya face?
11. Describe the lobelias that form rosettes. How do they protect themselves from freezing and desiccation?
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12. How do the tall lobelias protect themselves from freezing and desiccation?
13. Describe the sunbirds. What is their relationship to lobelias?
14. Describe the hyrax that live among the rocks. Why do they come out during the day?
Locator: Mountains of South America 15. How do these mountains differ from the mountains in Africa?
16. Describe the vicuña and its adaptations to mountain life.
17. What is the guanaco? How do the people of the Andes use it? At what altitudes does it live?
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18. What change occurs to the permanent snowline of the Andes as you start at the equator and travel south, towards Patagonia and Tierra del Fuego?
19. Explain why the poles are colder than the equator.
Locator: South Orkneys 20. Describe the two flowering plants that are found on these remote cold islands. (The name of one of the plants is “thrift”)
21. How do the mosses and lichens survive the extreme cold of these remote islands? What animals live in the mosses and lichens? How do they survive?
22. How is pack ice different from the ice in icebergs?
Locator: Antarctica 23. Describe the valleys found in the interior of Antarctica. What are the conditions in these valleys? How does this differ from the rest of Antarctica?
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24. Describe the life forms that live between the valley stones. How have they adapted to the harsh conditions?
Locator: Antarctic Glaciers 25. How are pools and streams formed in the Antarctic interior?
26. What life forms are found in these pools and streams? How do they get food?
Locator: Antarctica Coast 27. Where does life flourish in the Antarctic?
28. Describe the fur seals. What do they eat? How do they differ from true seals? What adaptations allow them to swim and feed in the surface waters?
29. Why are fur seals not able to dive to great depths?
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30. Describe the elephant seals and their adaptations to the cold waters. What do they eat?
================================================================== CLARIFICATION: Elephant seals are one type of "true seal". ================================================================== 31. Why do the elephant seals have to leave the water once a year?
Locator: South Georgia 32. Where did penguins evolve? Where are penguins found today?
33. What adaptations are found in penguins?
34. What are some of the differences between these penguins: Macaroni penguins, jackass penguins, king penguins and emperor penguins.
35. What is the advantage of large size? What is one disadvantage that faces king penguins?
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36. Describe the Emperor penguins.
37. Describe the manner in which Emperor penguins incubate their eggs and rear their young. What is unusual about the timing?
Locator: North Pole 38. Describe the guillemots. What adaptations are seen in the auk family?
39. Why do auks and penguins look similar? Are they closely related?
40. How is the Arctic different from the Antarctic? How does this affect the animal life of the Arctic?
41. Describe the Arctic fox. What does it eat?
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42. Describe the polar bear. What do they eat? What are polar bears related to?
43. What adaptations to cold are found in the polar bears?
44. What Arctic animals are scavengers?
45. Why do ringed seals have ice holes? What is the problem with having regular ice holes?
46. Describe the old lifestyle of the Eskimos (Inuit).
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47. What conditions are responsible for the cold, enclosed polar seas? What effect does this have on the nearby land masses?
Locator: The Tundra 48. Describe the tundra.
49. What causes ridges shaped like polygons to form in the tundra?
50. What is permafrost? What makes permafrost a significant factor in the tundra ecosystem?
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51. How is a pingo formed?
52. How long is the summer growing season in the tundra?
53. How have small flowering plants adapted to life on the tundra?
54. What tree is found growing on the Arctic tundra? What is unusual about this tree?
55. Describe the lemming. What is unusual about their reproductive capability?
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56. What is the major predator of the lemming?
57. Describe the migration of the caribou. Why do they migrate north? Why do they return south in the fall?
58. Describe the migration of the snow geese. Why do they migrate north? Why do they migrate south in the fall? Where do they spend the winter? (Note: a gosling is a young goose)
59. What type of animal is a ptarmigan? What do ptarmigan eat?
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60. What do caribou eat?
61. Describe the insects that grow during the summer: mosquitoes and black fly.
62. What does the red-necked phalarope eat?
63. A square yard of fresh water in the tundra can produce ________ insects in a season.
64. How do caribou sustain themselves over the winter? Where do they spend the winter?
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LIVING PLANET EPISODE THREE MATERIAL FOR YOU TO COVER Read the CONCEPTS section in the study guide for episode 3. Answer the Concepts Study Questions. Watch Video Episode 3 – The Northern Forests Answer the Video Study Questions.
EPISODE 3 LEARNING OBJECTIVES To become acquainted with: 1. Characteristics of conifers 2. Differences between conifers and flowering plants 3. Reproductive cycle of conifers vs. flowering plants 4. Layers of a typical forest 5. Food chains and food webs 6. Types of temperate forests 7. Ecology of coniferous forests: location, climate, characteristics, life forms and adaptations 8. Relationship between conifers and fungi 9. Relationship between voles and owls 10. Characteristics of broad-leaved deciduous trees 11. Ecology of temperate deciduous broad-leaved forest: locations, characteristics, life forms and adaptations 12. Effects of fire on forests
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CONCEPTS FOR EPISODE 3: THE NORTHERN FORESTS TREES In forest communities, trees are the dominant vegetation. There are many different kinds of trees, of course, and we can look at these in several ways. One way is to look at growth patterns. For instance, some trees are deciduous and others are evergreen. Deciduous trees lose all their leaves for part of the year, usually during the winter. Evergreen trees always have leaves. They do lose leaves, but only a few at a time. Another way is to look at the evolutionary relationships. This approach looks at the evolutionary history of plants, which looks at how related different plants are to one another. When you look at the evolutionary history of plants and focus on trees, most trees fall into one of two main groups: conifers and broad-leaved flowering plants. Conifers are cone-bearing trees. Their seeds develop inside cones instead of flowers. (Even though Attenborough uses the term "flower" to describe the cones, this is technically incorrect.) The reproductive cycle of a typical conifer, such as a pine tree, takes two years to complete. During the first year, both male and female cones are produced. The male cones are very small and are grouped together in clusters. They produce enormous amounts of pollen. The female cones are larger than the male cones, but still smaller than mature female cones. They are soft, and the eggs are located within the cones, between the scales. The male cones release their pollen, which is carried by the wind to the female cones. Since the pine relies on the wind to spread its pollen, the male cones produce abundant pollen. Most of the pollen never reaches a female cone. The wind carries it everywhere (including our noses) instead of directly and efficiently to the female cones. The male cones must make enormous amounts of pollen to be sure some of it will reach a female cone. The scales of the female cone have separated just enough to allow pollen to fall between the scales. When the wind-blown pollen reaches a female cone, the pollen grains fall between the scales and reach the ovules of the female cone, where the eggs are located. After pollination, the female cone closes up. So ends the first year. During the second year, the pollen grains eat away at the ovule tissue until they reach the eggs. Then the pollen produces sperm that fuse with the eggs to form zygotes, cells that will divide to form the embryos inside the seeds. The ovules develops into seeds, and the female cones grow and mature until they are as large as the familiar pine cones used as decorations during the winter holidays. Conifers are usually evergreens that have leaves shaped like needles. The shape and structure of the needles are adaptations for dry conditions. The long thin shape of the needles decreases the amount of surface from which water can evaporate. (Note: this also means there is less leaf surface for light, which decreases © Speer, Maxim and Strong
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photosynthesis.) The leaves have a thick waterproof layer (called a rind in the videotape) that protects them from drying out. The leaves have holes through which gases enter and exit. These holes are sunken into pits, which reduces evaporation. As you will hear in the videotape, conifers often live in areas with long cold winters when water is frozen and cannot be used by the trees. So, adaptations for dry conditions, such as the structure of their leaves, help the conifers survive the winters. Most of the conifers live in regions just south of the tundra. The summers are very short, so the plants may have as little as 90 days to grow. Because the conifers are evergreen, they do not waste time in making new leaves in the spring. Their needles can start producing food right away, allowing the conifers to maximize their growth during the short summer. Broad-leaved trees produce their seeds inside flowers. They are much more closely related to other flowering plants, such as daisies and roses, than to conifers. Typically, their leaves are thin and broad, which means more light can strike the leaf (more photosynthesis). The reproductive cycle of a typical broad-leaved tree, such as an oak tree, is completed in a much shorter time than in conifers. Oak trees in the Austin area, for instance, produce flowers in the spring (March and April) and produce fruits (acorns) by September and October. Thus, broad-leaved trees can reproduce in a matter of months instead of years. Although most flowering plants use animals to transfer pollen from flower to flower, most temperate broad-leaved trees rely on the wind instead. The windpollinated flowers of broad-leaved trees are inconspicuous with green petals. And they produce enormous amounts of pollen, just like in the conifers, and for the same reasons. Some broad-leaved trees have large, brightly colored flowers, such as peach trees and magnolias. These trees rely on bees and other animals to transfer pollen instead of wind. Brightly colored flower petals are signals used to attract animals. In the temperate regions of the planet where there are four distinct seasons, plants must get through the winter somehow. Here, broad-leaved trees are deciduous. As the nights get longer in autumn, biochemical changes in the tree trigger the dropping of leaves. All the recyclable parts of the leaf are removed and stored in the trunk and roots, so the green color disappears, revealing the brilliant oranges, reds, and golds of unrecyclable pigments. Eventually, the stalk that holds the leaf to the tree weakens and it separates from the tree. Why lose leaves just before winter? Water is not available during the winter months. Large amounts of water would be lost across the broad surface of the leaves. During winter, lost water cannot be replaced by the absorption of water from the soil by the roots. So, it is better to get rid of the leaves all together. This means that every spring, deciduous trees must produce new leaves. This is only possible in areas where the summers are long enough for leaf replacement, growth and reproduction. Broad-leaved forests are thus generally restricted to areas south of approximately 45 degrees North latitude.
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TROPHIC RELATIONSHIPS: FOOD CHAINS AND FOOD WEBS Trophic relationships are about food. To keep it simple, plants make food by photosynthesis. Since plants produce food from carbon dioxide and water, using sunlight as an energy source, plants are called producers. Any organism that utilizes the food originally produced by a producer is called a consumer. Primary consumers eat living plants. You can also call them herbivores. Think of a cow or a deer or a rabbit or a flamingo from the Rift Valley (Episode 1). Secondary consumers eat primary consumers. Tertiary consumers eat secondary consumers. And so forth. So, what do you call a consumer who eats another consumer? You can either call them predators or carnivores. Put these together and you get a simple, straight-line relationship of "who eats whom" called a food chain: grass mouse snake hawk producer
primary consumer secondary consumer tertiary consumer
Are all trophic relationships this simple? Well, by now, your answer should be "no way." What do you do with the hawk that eats the snake but will also gladly take a nice juicy mousie for lunch? How do they fit into a food chain?
This is no longer a simple food chain, since it is not a straight-line relationship. This is the start of a food web, which maps out more complex eating relationships. Now, let's add a new type of trophic relationship. What do you call a consumer that eats both plant material and other consumers? They are called omnivores (omni = all, vore = eater).
In the food web directly above, the grass and berries are producers. The mouse is an herbivore. The fox is an omnivore. The hawk and snake are both carnivores. © Speer, Maxim and Strong
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What about an organism that eats dead plant and animal material? If the organism is eating recently killed animals, they are called scavengers. Scavengers include vultures eating road kill, lions that steal a recently killed antelope from cheetahs or gulls that harass pelicans until they drop the fish from their bill pouches. So, remember what we said earlier about relationships not always fitting into our categories? Look at the lion. You know from numerous TV programs that lions are predators. However, no self-respecting lion would pass up a free meal. Hence, they become scavengers when the pride runs across a meal caught by someone else who can be intimidated into leaving. (Which isn't too hard to accomplish, since lions are very big and run in gangs. What would you decide to do?) So, what do you call an organism that breaks down long-dead plant and animal matter? It is called a decomposer, since the dead tissues will ultimately be broken down into small molecules such as carbon dioxide, nitrate and phosphates. Decomposers include fungi and bacteria. Decomposers are critical to an ecosystem because they return the nutrients that were "trapped" in the body of a plant or animal to the soil. Once in the soil, new producers can reincorporate them into living tissue or the nutrients can run off the soil into water where algae and water plants can use them. Decomposers are usually not included in a food chain or food web based on living plants. Many scientists set up decomposer food webs where the dead plant and/or animal materials represent the beginning level. Decomposers fill the primary consumer slot. Then, there are other organisms that feed on the decomposers; they are the secondary consumers. Then tertiary consumers eat the secondary consumers and so forth. Since these are food webs, some consumers eat at more than one level.
CHARACTERISTICS OF TEMPERATE FOREST COMMUNITIES Temperate ecosystems are found in areas of the world that have seasons. These places are located between the tundra and the tropics. Because of their location, they experience four seasons: winter, spring, summer and fall. The climate is not cold year-round like the polar regions or hot year-round like the tropics. One major feature of temperate forests is the presence of multiple layers of vegetation. A mature, established temperate forest usually has five layers: canopy, understory, shrub layer, ground layer and forest floor. The tallest trees form the canopy. Their branches reach out and meet the branches of their neighbors, making a more or less uninterrupted layer that shades everything below, like a giant umbrella or tent. Beneath the canopy is a layer made up of the branches and leaves of smaller trees, the understory layer. Below the understory lies the shrub layer, made up of woody plants that are too short to qualify as trees. The shrub layer in its turn is taller than the ground layer, which consists of tender green herbs that are the shortest members of the forest community. The ground layer covers the forest floor. The floor is made of soil covered by a layer of leaf litter. © Speer, Maxim and Strong
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Leaf litter is composed of dead leaves from all the plants that extend above the forest floor. As the leaf litter decomposes it is turned into humus that adds texture and nutrients to the soil. The texture of the soil is important because it determines how much space there is between soil particles and that determines the ability of plant roots to grow and obtain oxygen. The more space there is between soil particles, the easier it is for the roots to grow deeper into the soil, and more air can get into the soil for the roots to use. (We’re talking about soil humus, not a yummy Middle Eastern dish more commonly spelled as hummus.) The types of trees in the forest determine the nature of the soil, since they determine the nature of the leaf litter. Conifer needles make leaf litter that is acidic. The acidity of the leaves hampers decomposition, so the leaf litter builds up into a thick layer that makes it difficult for young plants to get established. The slow rate of decomposition also means that less humus is made. Because there is less humus, the soils are less rich in nutrients. Thus, these forests can support fewer species of plants and the understory, shrub and ground layer are less developed than they are in broadleaved deciduous forests. The decomposers present in the soil are the food for many different kinds of soil invertebrates. Since coniferous forest soils have fewer decomposers, fewer soil invertebrates can live there. In contrast, the thin leaves of broad-leaved deciduous trees are easily decomposed and do not acidify the soil. The leaf litter breaks down rapidly and a lot of humus is added to the soil. The soil is thus richer in these forests than in coniferous forests. With richer soil, more plants can grow and these forests have well-developed understory, shrub and ground layers. With many decomposers happily decomposing all that lovely leaf litter, there is an ample food supply for many different kinds of soil invertebrates.
TYPES OF TEMPERATE FORESTS Boreal Coniferous Forest = Taiga Most of the coniferous forests belong in this category, also called northern coniferous forests or the taiga. This type of forest is found south of the Arctic tundra throughout North America and Eurasia. The climate is always cold and is wet during the short summers, which last for only one to three months. Of all the forest types, the northern coniferous forest has the lowest diversity, and consists mostly of large, monotonous expanses of spruces and firs. According to Attenborough (Planet Earth), one-third of all of the world’s trees are in these forests. Look for this ecosystem in the video. Montane Coniferous Forest The coniferous forests extend south from the boreal forest along the major mountain ranges, such as the Rocky Mountains in Canada and the US, and to the Alps in Europe. In these areas, the forest is called the montane coniferous forest. Below the alpine vegetation is a region that looks similar to the boreal forest, although it © Speer, Maxim and Strong
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contains different species of spruce and fir. At lower elevations, the number of conifer and other plant species (aspen, pine) increases, so the lower montane coniferous forests are more diverse than the boreal forest. The increase in diversity is due to a less rigorous climate and to the longer growing season in these more southern regions. Temperate Rain Forest Along the west coast of Alaska and British Columbia, extending down into Washington, Oregon, and northern California, is a very special kind of coniferous forest, the temperate rain forest (also called the north coast temperate coniferous forest). This region experiences high rainfall (200-300 cm per year) and cool, but rarely cold, temperatures (2-20 degrees C). This area has a lot of fog. These trees are unusual because they can absorb water directly out of the air. Because of the abundant rainfall and relatively mild climate, the trees here grow to be giants. The canopy trees are commonly 50-75 m tall. In the redwood groves of California, the trees grow to 100 m and are over 2000 years old. Look for redwoods in the video. This region is an important timber region, and many of the oldest, grandest trees have been cut down. Still, at this time, large regions of undisturbed (old-growth) forest remain, and environmentalists and the timber industry are involved in a bitter contest over their fate. This type of forest is found nowhere else on Earth. And it would take thousands of years for a cut-over area to return to its former glory. That is too long for the unique animal species that depend on the old growth forests to survive. If the old growth forests are removed, they will go extinct. Hence, the dilemma of the spotted owl and marbled murrelets who nest in the tall old-growth trees. Temperate Coniferous Forest Coniferous forests are not restricted to cold climates. They are also found where the soils are poor or so well-drained that water availability is a problem. For instance, the Lost Pines of Bastrop County is a stand of loblolly pines located in an area where the soil has a high sand content. The sand makes the soil drain quickly, so the soil tends to be dryer than in the neighboring prairie areas with clay-based soils. Since conifers are better adapted to dry conditions, the loblolly pines can outcompete the broad-leaved trees in this area. Pine Savanna On the coastal plain of the Carolinas, Georgia and Florida, the vegetation consists of pine trees scattered over a wide area of grassland. The trees do not grow close enough together to form a closed canopy, and that lets in enough light for the grasses to grow luxuriously. This type of vegetation is called pine savanna. These are the forests of Florida and Georgia described in the video. Pine savannas are maintained by fire. Broad-leaved tree seedlings are quickly destroyed by fire. But pine seedlings and grasses are protected from the fire by their structure. The growing buds of pines are protected within tufts of leaves. The growing points of the grasses are below the ground. Without fires, the broad-leaved trees would invade and eventually shade out the pines and grasses, turning this area into a © Speer, Maxim and Strong
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deciduous forest. The fires are usually caused by lightning. What do you think the effect of humans would be on this type of vegetation? Humans tend to put out fires because fires endanger lives and dwellings. (They also tend to start them, which is another story.) In a pine savanna area inhabited by people, the naturally occurring fires are put out by the people, and the broad- leaved trees survive. Eventually, the pine savanna disappears. Temperate Deciduous Forest The temperate deciduous forests of the Northern Hemisphere once covered northeastern North America, most of Europe, and northeastern China and the Korean peninsula. Both deciduous broad-leaved trees and conifers can be found in these forests, although these forests are dominated by the broad-leaved trees. The tree species that make up the greatest proportion of plants in the forest differs in different areas. For example, in the northeastern United States, the deciduous forest is dominated by maple and beech trees. To the south, the dominant trees were oak and chestnut. (Most of the chestnut trees have disappeared, wiped out by an introduced fungus, the chestnut blight.) To the west, the dominant trees are oak and hickory. This type of forest is what Attenborough calls the broad-leaved forest. Since these broad-leaved trees have larger leaves than conifers, these forests have more food. The thin, soft leaves are easy to eat and abundant, so there are many more animals in these forests. These are seasonal forests, so there is danger of frost. These trees drop their leaves during the winter months and regrow them in the spring. Most of the deciduous forests of the world have been cut down by humans. In the United States at this time, the deciduous forest is increasing in area, as forest returns to the pastures cleared by European colonists and abandoned when their descendants moved west. In Europe and Asia, the deciduous forests are almost completely gone, and have been replaced by pastures, farmland, towns and cities.
SYMBIOTIC RELATIONSHIP BETWEEN PLANTS AND MYCORRHIZAL FUNGI Most plants have a symbiotic association between their roots and fungi. These associations are called mycorrhizae. Just as in the lichens, it is the combination of both the plant root and the fungus together that is the mycorrhiza. The plant roots are connected to a mat of fungal threads that extends out from the roots into the surrounding soil. The fungi expand the amount of soil that is contacted by the roots of the plant, enabling the plant to take up greater levels of nutrients than it could by itself. In addition, the fungi secrete acids into the soil, which release certain nutrients chemically bound to the soil particles into a form that can be taken up by the mycorrhiza and sent on to the plant. So what does the fungus get from the relationship? The fungus is supplied with food by the conifer, as well as a physical home. Thus, the fungus benefits as well as the conifer.
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Mycorrhizae are very important to the nutrition of most plants. In fact, many biologists think that the first plants that moved out onto the land already had mycorrhizae, and could not have invaded the land without them. All tree species have mycorrhizae. The conifers of the boreal forest cannot survive under the rigorous conditions of the Great White North without their mycorrhizae, and the mushrooms so common in deciduous forests are usually the reproductive bodies of the mycorrhizal fungi of the forest trees. Watch for this in the video.
Close-up of Mycorrhizae
References: Barbour, Michael G., Jack H. Burk, and Wanna D. Pitts. 1980. Terrestrial Plant Ecology. Benjamin/Cummings, Menlo Park, CA. McNaughton, S.J. and Larry L. Wolf. 1979. General Ecology, 2nd ed. Holt Rinehart Winston, NY. Vankat, John L. 1979. The Natural Vegetation of North America: An Introduction. Wiley, NY.
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CONCEPTS STUDY QUESTIONS FOR EPISODE 3: 1. Explain the difference between deciduous trees and conifers with respect to how long they keep their leaves and why deciduous trees drop their leaves in autumn.
2. Briefly describe the reproductive cycle of a typical conifer.
3. Briefly describe the reproductive cycle of a typical broad-leaved tree.
4. Explain how these organisms are related to each other in terms of food chains: a. Producer, primary consumer, secondary consumer, tertiary consumer
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b. Plants, herbivores, carnivores, omnivores, scavengers, decomposers
5. Describe the function of decomposers.
6. Describe zonation in a typical temperate forest.
7. Describe the process of decomposition on the forest floor.
8. Compare decomposition in temperate conifer and broad-leaf forests.
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9. Describe and compare these types of temperate forest: boreal conifer, montane conifer, temperate rain forest, pine savanna, temperate deciduous forest.
10. What happened to most of the chestnut trees in the United States?
11. Describe mycorrhizae (also known as mycorrhizal associations).
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VIDEO STUDY QUESTIONS FOR EPISODE 3: 1. What are the three things that living forms require in order to survive?
2. What keeps the northern forests from inhabiting the lands that are north of their boundaries?
3. Why do pine trees need to conserve water during the winter? How do they conserve water?
4. What part of the pine tree is used as food by birds and small rodents?
5. Describe the crossbill. What does it eat? How?
[NOTE: The small animals that make runways through the snow are called “voles”.] 6. What do moose use as food?
7. Describe the great gray owl and its adaptations to snow.
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8. What do the other hunters eat during the winter? a. lynx
b. eagle owl
c. wolverine
9. Using the example of the lynx, explain what "cost efficiency" means to a predator.
10. Thought question: Why do many of the animals in the northern coniferous forests have large bodies?
11. Where are the northern coniferous forests located?
12. Why are the trees and the permanent inhabitants in these forests very similar to one another, even though the forests are on different continents?
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Locator: Scandinavia 13. Where does the hawk owl spend the winter? Where does it nest? How is the hawk owl different from most owls?
14. Describe the capercaillie. Where are they found? What do they eat?
15. Where is the black woodpecker found?
16. Which group of birds digs their own nests out of a tree? What else do they use their sharp beaks for?
17. What insect is used by woodpeckers for food during the winter?
18. Where does the eagle owl nest? ======================================================================= CORRECTION FOR THE VIDEO: Remember, conifers do not produce flowers. They produce male and female cones. ======================================================================= 19. Why do the northern forests have so many birds during the summer months? What do they use for food?
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20. Pine Beauty Moths: a. How do the caterpillars of the pine beauty moth protect themselves from their predators, the birds?
b. Why don’t they have any defense against the wood ants?
c. How does the adult moth protect iteself against shrews as it emerges from the ground?
21. Describe the sawfly caterpillar and its defense against ant predators.
22. What does the wryneck woodpecker eat? How is the wryneck different from other woodpeckers?
23. Describe the reproductive cycle of the voles.
24. Why does the vole population crash every 5-6 years?
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25. How does the vole population affect the great gray owl population?
Locator: Finland 26. What is an owl pellet? Why do owls produce owl pellets?
27. Identify two reasons why birds begin to move south at the end of the summer.
Locator: Forests of Broad-leaved Trees 28. Identify four types of trees found in these forests.
29. How are the climatic conditions different in these forests from the coniferous forests of the north?
30. What shape do the broad-leaved trees have? How is their shape different from the shape of conifers and why?
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31. Describe the leaves. How are they different from the leaves of conifers?
32. Which organisms use the leaves for food?
33. Why are there more birds in these forests during late summer than at any other time of year?
34. Describe the defense mechanisms that are used by the insects to protect themselves from their predators.
35. What is the difference in the way a tree creeper and a nuthatch hunt for insects on a tree?
36. Describe the woodpeckers. How are they adapted for their life style?
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37. How many species of woodpeckers are found in Europe? How many species are found in North America?
38. What does the sapsucker eat? How does it collect its food?
[NOTE: A fledgling is a young bird] 39. What other animals eat sap?
====================================================================== CLARIFICATION: Sap is not the same thing as resin. The sap that animals eat is a watery solution full of sugar. The sugar is made in the leaves by photosynthesis. It is then transported to other parts of the plants, such as roots. Resin is a material produced by the tree to seal up damaged areas. It is not used as food. ====================================================================== 40. How do acorn woodpeckers store food? Does each bird have its own store?
41. How do the plants tempt animals to transport the seeds?
42. Thought Question: What benefit does an oak tree get out of a squirrel taking its acorn? How does the squirrel benefit?
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43. What does the black bear eat?
44. The possum is more closely related to _______________________ than to rats or chipmunks or other rodents.
45. Why do the broad-leaved trees shed their leaves during the winter months? Why do the leaves change from green to different colors, such as red?
46. What animals live in the leaf litter? What do they eat?
47. Describe the salamander. Why are they rarely seen?
48. Describe the shrew. What is unusual about the shrew?
49. How do salamanders protect themselves against predatory shrews?
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50. What is hibernation? What changes occur in the body of the small mammals such as chipmunks that hibernate during the winter months?
51. Describe the behavior of the black bear during the winter months.
======================================================================= ADDITIONAL INFO. This is called winter sleep instead of hibernation, because their metabolic rate does not significantly decrease. Bears rely upon fat supplies for energy. ======================================================================= 52. When spring finally comes to the forest, why do the ground plants flower so quickly?
53. Where does the wood duck nest?
54. What spring conditions cause the fungi to produce their fruiting bodies (mushrooms)? What is produced by the fruiting bodies?
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Locator: Forests of Florida and Georgia 55. How are the climatic conditions of this forest different?
56. What is unusual about the oak?
57. What other type of evergreen tree is found in these southern forests? What conditions favor the growth of pines in these forests?
58. What is the effect of fire on the oaks? on pines? What protects the terminal buds of young pines? [Note: terminal buds are the growing buds at the end of each branch.]
59. What are the two causes of fires in these forests?
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60. Why do dry pine needles catch fire so quickly?
61. How do many of the forest inhabitants avoid the fire?
62. Why do beetles seek areas that have been stricken by fire? How do they locate these areas? Where do they lay their eggs?
63. Why is the forest rejuvenated by fire?
64. What is different about areas that have regular fires? How does this promote swampy areas and open marshes?
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65. Describe the red-cockaded woodpecker. Why does it build its nest in living trees? Does one woodpecker build the nest?
66. How is the nest of the red-cockaded woodpecker protected from predators such as the rat snake?
======================================================================= ADDITIONAL INFO. The tree produces resin for itself, not for the bird. The conifer produces resin to seal its wounds and protect itself from invading fungi and insects. The woodpecker takes advantage of the resin for its own protection. ======================================================================= 67. Describe the giant sequoia. How old is the tree shown in the video? What is unusual about the General Sherman tree?
68. How did the sequoias get trapped in the Sierra Nevada mountains?
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LIVING PLANET EPISODE FOUR MATERIAL FOR YOU TO COVER Read the CONCEPTS section in the study guide for episode 4. Answer the Concepts Study Questions. Watch Video Episode 4 – The Jungle. Answer the Video Study Questions.
EPISODE 4 LEARNING OBJECTIVES To become acquainted with: 1. Nitrogen cycle 2. Ecology of jungles: location, climate, characteristics, life forms and adaptations 3. The layering (stratification) of jungles 4. The kapok trees, including location, characteristics, climatic differences, life forms and adaptations 5. The canopy, including location, characteristics, climatic differences, life forms and adaptations 6. Relationship between flowering trees and animals 7. The jungle floor, including location, characteristics, climatic differences, life forms and adaptations
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CONCEPTS FOR EPISODE 4: THE JUNGLE TROPICAL FORESTS Tropical rain forest, often called the jungle, is the most productive and diverse terrestrial ecosystem. Most of the tropical rain forests are located around the equator (between 10 degrees latitude north and south). The tropical rain forests are found in regions that are warm year round and receive large amounts of rain, often on a daily basis. Average rainfall varies between different rain forests but is generally around 200250 cm per year (80-90 in/yr). Even though Attenborough does not mention them in the video, there are other types of tropical forests. These include seasonal forests (with distinct wet and dry seasons), mountain forests (found at higher elevations), cloud forests (wrapped in fog and mists at even higher elevations), gallery forests (which line riverbeds of tropical grasslands) and dry forests (with dry seasons of eight months). ================================================================== Author's Note: Don't be mislead by the use of the word "tropical". According to Webster's dictionary, the tropics are between 23½ degrees N and S. Tropical rain forest is only one type of community found within the "tropics". ==================================================================
CHARACTERISTICS OF TROPICAL RAIN FORESTS As mentioned above, there are no seasons in tropical rain forests. There is little annual change in temperature and rainfall. There is abundant rain, which falls daily. The climate is warm year-round, with no danger of frost. Tropical rain forest trees are broad-leaved trees. Since there are no seasons, the trees drop their leaves a few at a time throughout the year instead of dropping them all at once. In seasonal forests and dry forests (discussed above), the trees typically drop their leaves during the beginning of the dry season. This helps them conserve water during the dry periods. In a tropical rain forest, rainfall is not seasonal and the trees have leaves year-round. Another feature is the stratification of vegetation. In tropical rain forests, the upper layers are particularly thick. Most of the visible plant and animal life are located in these upper levels. The typical tropical rain forest layers are: - Emergent layer of trees that are very tall. These trees are often 50-80 meters high and are widely spaced from one another. The crown of leaves receives direct sunlight and the leaves are exposed to wind. Watch for the kapok tree. - Canopy, made up of the crowns of trees less than 50 meters in height. This is a very thick layer, between 6 and 15 meters deep. This usually contains numerous trees, very tightly packed together. Their leaves form a dense continuous blanket (or © Speer, Maxim and Strong
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canopy) of green, as the leaves compete for light. This layer is very productive due to high photosynthesis and animals are found here in great abundance. The climatic conditions of the canopy are very different from the emergent layer. There is much less light within and under the canopy due to the thick layer of leaves. This layer is very warm and humid. There is no wind. The canopy is shown clearly on the video. - Understory of young trees, shrubs, ferns, taller herbaceous (non-woody) plants. Dangling vines pass through this layer, linking the forest floor with the canopy. There are few plants in this layer and they are often widely spaced. Since there are fewer leaves, there is less food and animal life is scarce. The young trees, or saplings, cannot grow without abundant light. Watch the video for lianas and the changes that occur when light becomes available. - Forest floor of seedlings, small herbs and small ferns on the ground. This layer has very little light. The floor collects dead leaves, branches, logs and other debris. Roots spread out and form thick mats, since most nutrients are found in the upper few inches of soil. There are numerous small organisms in the leaf litter, such as ants, termites, fungi, bacteria, worms and insects. Watch the tape for: Rafflesia, termites, spiders, whip scorpions, planaria, Peripatus, beetles, blind legless burrowing lizard, phasmid, tenrec and elephant shrew. The typical rain forest soil is another important feature. The soil is poor because many of the nutrients are washed out by the daily rains. Fortunately, the organisms in the leaf litter quickly break down debris. A leaf, for example, is totally decomposed in about 6 weeks. This rapid cycling is the main source of nutrients in the soil. As a result, nutrients are available only in the top layer of soil (about the first foot or so). Also, nutrients have to be rapidly absorbed by the plants or they might be washed out. As a result, the roots of the trees are shallow and concentrated in the first foot of soil. This, by the way, is a potential problem for a tree. Think about it. You have a tree that is 50 meters tall (about 150 feet). Yet, most of its roots are anchored in 1 foot of soil. The trees get around this by having buttresses, outgrowths that act as props. Look for these in the video. Another noticeable feature is the presence of abundant plant life up in the trees. Tropical rain forests have abundant epiphytes with aerial roots, such as the orchids and bromeliads shown on the tape. (An epiphyte is a plant that is attached to the outside of another plant but is not a parasite.) Vines known as climbers, or lianas, stretch from the tree tops to the ground. Climbers use the tree trunks for support but do not harm the tree. Other vines called stranglers, such as strangler figs, surround host trees in order to gain light. You can watch a fascinating Attenborough video on strangler figs at: http://www.youtube.com/watch?v=UCUtpmwacoE
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NITROGEN CYCLE In the "Concepts for Episode 3", we spoke about decomposers returning nutrients to the soil. Nutrients include carbon, oxygen, hydrogen, phosphorus, nitrogen, sulfur and other elements that are used as building blocks of living tissue. [So what does that mean? Lipids, proteins, carbohydrates and nucleic acids are made of these nutrients.] The growth of plants is often restricted by the levels of nitrogen and/or phosphorus. In woody plants, like trees, these nutrients are bound up for years in the body of the plant. When a tree dies, decomposers release the nutrients into the soil. Other plants can then use these newly available nutrients to grow. We are going to discuss the nitrogen cycle in greater detail as an example of how nutrients flow through an ecosystem. Keep in mind that there are several different nutrient cycles. Any decent ecology textbook will contain the cycles for water, carbon, nitrogen, phosphorus and sulfur. Most of the nitrogen on our planet is in the form of atmospheric nitrogen, N2, which is the most common gas in our atmosphere (about 79%). Unfortunately, plants cannot use atmospheric nitrogen until it is converted into ammonia (NH3), nitrite (NO2) or nitrate (NO3). The process of converting atmospheric nitrogen into forms that plants can use is a multi-step process that depends upon many kinds of bacteria. Each kind of bacterium carries out a specific step in the process. Step 1 - Nitrogen fixation. Atmospheric nitrogen is converted (fixed) into ammonia by cyanobacteria (blue green algae) in water, free-living bacteria in the soil (such as Azotobacter) and symbiotic bacteria (such as Rhizobium) in the root nodules of plants in the bean and pea family (legumes). These are the only organisms that can fix nitrogen. All life on this planet depends on these organisms for usable nitrogen, either directly or indirectly. (That means that you can thank them for the nitrogen in your proteins and nucleic acids.) Now, for the sake of being technically correct, some nitrogen is fixed by lightning or volcanic activity. This accounts for a very small percentage of usable nitrogen, not nearly enough to support life. Step 2 - Nitrification. This is a two-step process. First, ammonia is converted into nitrite (NO2) by a specific group of bacteria (such as Nitrosomonas). Then, nitrite is converted into nitrate (NO3) by a different group of bacteria (such as Nitrobacter). Step 3 - Assimilation. Most terrestrial plants use nitrates because it is available. The roots of the plant take up nitrate from the soil. Plant cells then convert nitrate back to ammonia and use it to make proteins and nucleic acids (DNA). Because these chemicals are part of the plant’s body, we say the nitrogen has been assimilated. © Speer, Maxim and Strong
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After assimilation by the plants, the nitrogen can move up the food chain as primary consumers eat plant parts and as secondary consumers eat primary consumers and so forth. At this point, the nitrogen is somewhere in the body of a living organism. So what happens next? Well, there are several options. You can get eaten, in which case your nitrogen becomes part of the next guy. You can give off wastes (such as urine and feces), in which case the nitrogen goes to the decomposers (see step 4 below). You can die and decay, in which case the nitrogen goes to the decomposers. If you are a plant, your leaves can fall off, in which case the nitrogen in the leaves goes to the decomposers. Get the picture? Step 4 - Ammonification. The nitrogen in proteins and nucleic acids is converted back to ammonia by the decomposers (bacteria and fungi). Now, ammonia goes back to step 2 and starts the process all over again. Now, this seems simple. By now, you should be suspecting that anything this simple is too good to be true. And, you would be right. In actuality, there are two possible pathways for nitrate. We have just described the most common cycle where the nitrates are used by plants to form living tissue. There is an alternate pathway. Nitrates can be converted back into atmospheric nitrogen by a different group of bacteria. This process is called denitrification and the bacteria are called denitrifiers. This takes the nitrogen back to the beginning of the cycle. Here's a simple diagram of the nitrogen cycle.
References: Smith, Robert Leo. 1992. Elements of Ecology, 3rd edition. HarperCollins New York. Ricklefs, Robert E. 1990. Ecology, 3rd edition. W.H. Freeman, New York.
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================================================================== CONCEPT CHECK: Many of our students have struggled to understand the nitrogen cycle. To check your understanding, answer the questions below and then check our answers on the next page. Q1. What is denitrification? What organisms are responsible?
Q2. What is nitrification? What organisms are responsible?
Q3. What is nitrogen fixation? What organisms are responsible?
Q4. What is assimilation? What organisms are responsible?
Q5. What is ammonification? What organisms are responsible?
Q6. What is the difference between the nitrogen cycle and nitrogen fixation?
Q7. What is the difference between the nitrogen cycle and any of the steps of the cycle (nitrification, ammonification, etc.)?
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================================================================= ANSWERS TO THE CONCEPT QUESTIONS: Q1. Denitrification refers to the conversion of nitrates back into atmospheric nitrogen. Bacteria are responsible for this step. (Specifically, these bacteria are called denitrifying bacteria.)
Q2. Nitrification is a two-step conversion of (1) ammonia into nitrites, and (2) nitrites into nitrates. Both steps require bacteria; these bacteria are called nitrifying bacteria.
Q3. Nitrogen fixation is the conversion of atmospheric nitrogen into ammonia. Biologically, the conversion is done by cyanobacteria in water, bacteria such as Azotobacter in the soil and symbiotic bacteria such as Rhizobium in the roots of legumes. These bacteria are grouped together as nitrogen-fixing bacteria.
Q4. Assimilation is the conversion of nitrates into proteins and nucleic acids. Plants are responsible for this conversion.
Q5. Ammonification is the release of ammonia due to the breakdown of proteins and nucleic acids. Bacteria and fungi are responsible for this step; these organisms are known as the decomposers.
Q6 and Q7. What is the difference between the nitrogen cycle and nitrogen fixation? [or any of the steps of the cycle] The nitrogen cycle is the entire process and includes every step in which nitrogen is converted from one form into another. (Look at the diagram to see the entire process or cycle.) Nitrogen fixation, on the other hand, is a single step in the cycle. Nitrogen fixation is LIMITED ONLY to the conversion of atmospheric nitrogen into ammonia. So, a cycle is made up of many individual steps. The cycle is not any one step but is the cumulative total of all steps. ==================================================================
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BIODIVERSITY A hot topic today is biodiversity. Biodiversity refers to the number of different types of organisms and the relative abundance of each. What is relative abundance? It is the proportion of the individuals of one species relative to the total number of individuals in the community. Let's look at these two examples. Each community has 100 members and 5 species. Both communities have an equal number of species (5). If you just looked at species numbers, you might think they have equal biodiversity. Community A 50 spruce trees 25 aspen trees 15 blueberry bushes 9 wintergreen herbs 1 ladyslipper orchid
Community B 20 live oak trees 20 post oak trees 20 ashe juniper trees 20 hackberry trees 20 cedar elms
Now, let’s look at the relative abundance of. In Community A, 50% of all individuals are spruce trees. 25% of all individuals are aspen trees. 15% are blueberry bushes. You figure out the rest for Community A. Then calculate the relative abundance of each species in Community B. Now, let's go back and look at biodiversity. In Community A, spruce trees are clearly the most common plant. It is the dominant plant in the community, since it appears far more frequently than any other species. What about Community B? Is there a dominant plant? If you said "no", you are correct. Each plant occurs at the same frequency (20%) and no one species is dominant. A community is thought to be more diverse if there is no dominant species. It is less diverse if one or two species are clearly dominant. Now, let's compare different forests (in terms of plant biodiversity ONLY). Type of Forest Tropical rain forest Temperate deciduous forest Northern coniferous forest
# Tree Species
# Dominant Species
200-300
No dominant species
Level of Biodiversity High
20-25
1-2 dominant species
Medium
6-8
1 dominant species
Low
Keep in mind that biodiversity applies to all ecosystems. You can talk about animal biodiversity, plant biodiversity, insect biodiversity, total biodiversity or anything you care to actually go out and count. Here’s an example of tree biodiversity in one tropical rain forest. According to The Earth Almanac section of May 1997 issue of National Geographic, biodiversity of a © Speer, Maxim and Strong
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129-acre plot in a national park in Malaysia had 1175 tree species. This means that the scientists that studied this forest found an average of 9.1 different species of trees per acre, making it "one of the most diverse forests in the world". Why is biodiversity a hot topic? First, humans do not surround themselves with diversity. We convert naturally diverse communities into urban areas or agricultural areas. Look around Austin. Do you think this is a diverse habitat? Look at your neighborhood. What's there? We'll bet on St. Augustine grass and maybe 4-5 species of trees. What about a wheat field? Do you think a farmer is going to be thrilled about mixing his wheat crop with a bunch of "weeds"? Secondly, the loss of habitat means that species disappear and some become extinct. When species begin to disappear, the ecosystem changes and no longer functions properly. Humans, just like all other animals, rely upon ecosystems for food, oxygen, and other necessities. At some point, as more and more ecosystems stop properly functioning, the planetary ecosystem may be disrupted to the point that our life on earth is threatened. Some people think this is a "radical, wild-eyed" theory but how willing are you to chance it? Here are some web sites that discuss extinction rates and how many species have gone extinct or are threatened with extinction. • http://e360.yale.edu/feature/global_extinction_rates_why_do_estimates_vary_so _wildly/2904/ • http://www.biologicaldiversity.org/programs/biodiversity/elements_of_biodiversity/ extinction_crisis/ • http://wwf.panda.org/about_our_earth/biodiversity/biodiversity/ GLIDING AS A MEANS OF TRANSPORTATION In the videotape, Attenborough discusses the flying squirrel, which is able to move from tree to tree by gliding. This allows the animal to move around in the canopy without descending from one tree trunk, crossing the ground, and ascending the next tree trunk. It is also a less energy-demanding means of moving than flying. On the other hand, animals who fly have more control. Gliding is not limited to squirrels and snakes. Borneo also has a species of flying lizard. On either side of its body, it has a flap of skin which is stiffened by bony processes from the ribs. While gliding, the ribs are pulled forward, which extends the flaps. Flying frogs have very long toes, which are webbed. As the frog glides, the webbed toes act as tiny "parachutes". You can find more info on the flying lizards of Southeast Asia at: http://scribol.com/environment/animals-environment/the-flyingdragon-lizards-of-southeast-asia/
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KEYSTONE SPECIES This is a good time to bring up the concept of a keystone species. What is a keystone species? This means that the organism plays a central role in the functioning of the ecosystem. If the keystone species dies out, this causes a domino effect. Every animal that depends on the keystone species dies out. Their predators then die out and the effect spreads through the food web. The net result: the ecosystem collapses. The food supply from figs is almost always available in the jungle. The members of one species of fig tree all bear fruit at the same time. However, there are several different species of fig trees; each species bears fruit at a different time from the others. Hence, there is almost a continual supply of figs somewhere in the jungle. Many animals rely almost exclusively on figs for food. As a result, fig trees are considered to be keystone species in the jungle ecosystem. Fig wasps are tiny wasps that are the sole pollinators of figs. They lay their eggs within the developing fig fruit, which contains hundreds of tiny fig flowers inside. The fig wasps pollinate the fig’s flowers, which is necessary for the fruit to ripen. Without the fig wasps, there can be no figs. Without the figs, there can be no fig wasps. What kind of symbiotic relationship would this be? If figs are a keystone species, what are fig wasps? Here’s another point to contemplate from an environmental standpoint. Humans are not very good at determining keystone species. We usually find out a species was keystone when it is gone. Then, it is too late. This is something to consider about conserving biodiversity. Do you trust our ability to determine which species are keystone species before we wipe them out?
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CONCEPTS STUDY QUESTIONS FOR EPISODE 4: 1. Describe the general location of tropical rain forests and the climatic conditions that exist where these forests are found.
2. Describe the stratification seen in a typical tropical rain forest and the types of plants found in each layer.
3. Compare light, wind, and moisture conditions in the layers of a tropical rain forest.
4. Explain why the soil in tropical rain forests is low in nutrients.
5. Explain why organisms need nitrogen.
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6. Describe each step in the nitrogen cycle. Be able to draw a diagram showing the relationship between these steps or processes, the various forms of nitrogen (nitrate, nitrite, ammonia, atmospheric nitrogen), and living tissue.
7. Explain the ecological significance of these organisms: cyanobacteria, Azotobacter, Rhizobium.
8. Describe biodiversity and its two components.
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9. Calculate relative abundance for each species in this community: Plant Species 20 oak trees 25 sugar maple trees 40 chestnut trees 9 black walnut trees 8 shagbark hickory trees 6 grape vines
Relative Abundance:
10. Does this community have a dominant species? If so, identify the dominant species.
11. Based on what you learned about chestnut trees in Concepts for Episode 3, is the community described in #9 likely to be a currently existing plant community in the United States? Explain your answer.
12. Explain how dominance and diversity are related.
13. Explain what is meant by the term “keystone species”.
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VIDEO STUDY QUESTIONS FOR EPISODE 4: Locator: Jungle Species mentioned in this section: harpy, crowned eagle, hawk eagle, squirrel monkey 1. Which terrestrial ecosystem has the greatest number and greatest diversity of animals? Why?
2. Where are the jungles located?
3. Describe the kapok tree.
4. How are climatic conditions different for the kapok tree?
5. What is a disadvantage of wind to the kapok tree? an advantage?
6. Which birds live in the kapok tree? What other similar birds are found in other giant trees of other jungles? What do they eat?
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7. How are conditions different in the canopy?
8. What adaptation is found in the leaves of canopy trees?
9. Describe the weaver ants.
10. What other animals are found in the jungle canopies?
11. Describe the flowering cycle of the jungle plants. How is this different from the other forests?
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13. How are seeds dispersed?
14. What do the fruit bats eat? What do most of the other bats eat?
15. Describe the pygmy marmosets. What are sap wells?
16. How are the spores of mosses and ferns transported?
17. Describe the orchids and bromeliads. How do they collect moisture?
18. Describe the breeding cycle of the arrow poison frog.
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Living Planet, 12th edition 19. What are the lianas? How are they used by the jungle inhabitants?
20. How do snakes climb the tall trees of the forest?
21. How does the paradise tree snake move from tree to tree?
Locator: Borneo Species mentioned in this section: golden lion marmoset, uakari 22. Describe the flying squirrels.
23. How do other animals move through the canopy?
24. Where do termites nest? How do other animals use termite nests?
25. Describe the macaw and its nesting behavior.
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======================================================================== CORRECTION FOR THE VIDEO: Birds do not chew food. They swallow food in chunks, which is then broken up by a muscular gizzard. ======================================================================== 26. What other animals nest in holes in the trees? `
27. Why do jungle trees have buttresses?
28. Describe the forest floor. What provides sustenance on the floor?
29. What two factors promote rapid decomposition of the jungle leaf litter?
30. Name the two main groups of organisms that are responsible for the decay of the leaves in the leaf litter.
Locator: Sumatra Species mentioned in this section: planarian worm, Peripatus 31. Describe the parasitic plant, Rafflesia. How does its flower attract pollinators?
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32. How are the seeds of the Rafflesia plant spread?
33. What provides food for the termites on the forest floor? Why are termites important to this ecosystem?
34. How do the termites protect themselves?
35. What other animals inhabit the leaf litter?
Locator: Madagascar 36. Describe the tenrec. Where does it live? What does it eat?
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37. Describe the elephant shrew of Africa. How does it locate food in the leaf litter?
Locator: Ecuador Species mentioned in this section: howler monkey, gibbon 38. Describe the life style of the South American Indians (Waorani).
39. How do they harvest their favorite fruit, the chunta?
40. Why do the Waorani plant cecropia trees?
41. What physical adaptation has occurred in the Waorani? What is the advantage of this adaptation?
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43. What other methods are used by animals to communicate?
Location: Borneo 44. Describe the mating dance of the argus pheasant of Southeast Asia.
Location: South America 45. Describe the mating displays of the cock-of-the-rock.
46. Describe the climatic conditions of the jungles.
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47. How old are the jungles? What has been the effect of the great age of the jungles on the jungle inhabitants?
48. Describe the various ways that animals have developed to look like other objects (mimicry). Animal described in Episode 3 Young stick insect
What does it look like?
Adult stick insect Beetle Bug Mantis Lizard 49. Thought Question: What is one advantage of mimicry?
50. What problems are created by the drenching torrents of rain? What effect does this have on the soil?
51. Describe the jaguar. Where is it usually found? What does it eat?
52. How do white tent-making bats use the leaf of the heliconia?
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54. How long does it take before the canopy is complete again?
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LIVING PLANET EPISODE FIVE MATERIAL FOR YOU TO COVER Read the CONCEPTS section in the study guide for episode 5. Answer the Concepts Study Questions. Watch Video Episode 5 – Seas of Grass. Answer the Video Study Questions.
EPISODE 5 LEARNING OBJECTIVES To become acquainted with: 1. Characteristics of grasslands 2. Characteristics of grasses 3. Ecology of major grasslands: location, climate, characteristic life forms and their adaptations 4. The differences between major grasslands, including location, climate, life forms and specific adaptations • South American savanna • South American pampas • South American llanos • North American prairies • Eurasian steppes • South African veldts • East African savannas • Australian grasslands 5. Kin selection
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CONCEPTS FOR EPISODE 5: SEAS OF GRASS CHARACTERISTICS OF GRASSLANDS Grasslands are found in areas where the average rainfall is 10 to 30 inches per year (25-80 cm/yr). This is not enough rain to support forests but this is enough for grasses to flourish. Grasses also need good light and they cannot tolerate much shade. Many grasslands are exposed to periodic dry periods and severe droughts. Usually, the grasslands are found on flat or rolling terrains, such as the flat mid-western stretches of the United States. Fire is a major factor in maintaining grasslands. Periodic fires sweep over the natural grassland, converting dead material into nutrients which are available for immediate use. Fire also destroys any woody plants, such as shrubs or trees, that have begun to supplant the grasses. Thus, fire helps the grassland remain a grassland. Grasses are, of course, the dominant plants in grasslands but there are other non-woody plants as well. Most of us only look at the top layer of vegetation, that tall green layer made of grasses and flowering plants. This herbaceous layer is actually only the top of three layers, and not the most important. The ground layer and the underground root layer are the two main layers. The ground layer is easily visible in winter and early spring. As light levels increase in the spring, the plants respond with vigorous growth. The ground layer becomes shaded by the tall growth. This area, in an ungrazed or unmowed situation, is cooler, more humid and receives less wind than the herbaceous layer. Undisturbed grasslands accumulate a thick layer of mulch, made of decomposing vegetation. This layer retains moisture in the soil, as well as maintaining stable soil temperatures. Grass seeds can easily germinate under these conditions. Runoff and erosion decrease. Decomposers thrive in this layer, slowly releasing nutrients into the surrounding soil. It takes about 3 or 4 years for natural mulch to completely decompose. This litter has many insects, spiders, rodents, lizards and other animals. The root layer is the largest layer of all. More than 50% of the body of a grass is underground. Most of the excess food produced by photosynthesis is stored underground. The roots form a dense, thick layer deep into the soil. Many grasses have underground stems, called rhizomes, which serve to spread the plant and store food. Roots grow to different depths, allowing nutrients to be absorbed from different depths in the soil. This layer contains abundant animal life, such as insect eggs, earthworms, ants and other invertebrates. Many grasslands also have burrowing mammals: prairie dogs, marmots, ground squirrels, viscachas, gerbils, hamsters, meerkats and wombats. Most of these animals are mentioned in the video. When most of us think of grasslands, we think of big herds of mammals that graze on the abundant grass. Watch the video for capybara, bison, pronghorns, saiga antelope, zebra, wildebeest, giraffe, dik-diks, impala, antelopes and white-eared kob.
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TERMITES In tropical grasslands, termites play a very important role in the ecosystem. Termites are NOT white ants. They are not closely related to ants, even though they may have somewhat similar lifestyles. Termites require warmth and humidity, so they are most abundant in tropical and subtropical areas. Termites in grasslands build complex nests with chimneys that draw air for ventilation. Termites are also very common in tropical savannas where they build very large mounds with tall chimneys that help air circulate through the colony. Termites have a complex social structure that includes castes. Castes refer to a group within a society that has a specific job. In termite societies, the castes include: 1) The reproductive individuals. These are the king and queen. Unlike ant societies, the king lives with the queen and they both live for a relatively long time. Their job duties are simple: start the new colony (the mound), then reproduce. The reproductive individuals keep reproducing during their entire life. A reproductive queen that is laying eggs is very large; the king is not as huge but he is larger than the other caste members. Termites are fascinating to read about. The king and queen raise the first group of offspring. After the first set of offspring mature, the king and queen spend the rest of their lives reproducing. The queen becomes huge and turns into an egg-laying "machine." 2) The workers. These are the "peons", the working members of the society that take care of the offspring, gather food, build the nest, maintain the nest, dispose of dead bodies and any other mundane day-to-day task. The workers have small bodies. Workers can be male or female. 3) The soldiers. These are the "armed forces". Their sole purpose is to defend the mound from invaders. They are bigger than workers. They have some method of attack, such as very large sharp jaws or chemical spray guns on their heads which disperse nasty compounds that deters most intruders. Soldiers can be male or female (varies between species). Even though some predators love to eat termites, they do not stay for long when they are eating. They cruise in for fast food (however many termites they can eat within a few minutes) before the soldiers drive them off. Termite colonies grow slowly and they last for decades. Termites are most abundant in the tropical rain forests where most species eat mainly wood, leaves and plant parts. Termites that live in savannas eat grass and other plant parts. [There is very little wood in a grassland but there are lots of grasses to eat.] Reference: Grzimek, Bernhard (editor). 1984. Grzimek's Animal Life Encyclopedia: Insects. Van Nostrand Reinhold, New York.
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SOCIETIES AND KIN SELECTION The study of highly social animals (termites, ants, bees, wasps, naked mole rats and one type of shrimp) raises some very interesting questions. In these animals, as we saw in the termites, one female dominates reproduction, while the other animals do the work. The working members usually do not reproduce. Why would any organism give up its right to reproduce in order to raise the offspring of another organism? In order to be successful in an evolutionary sense, the name of the game is reproduction. Money is NOT important: success = babies. [After all, if you don't have children, then your genes die out. From an evolutionary standpoint, you have ZERO impact on the future.] Superficially, such a society does NOT make sense from the worker's point of view. The worker gives up its right to reproduce and spends its life maintaining the colony and raising the offspring of the king and queen. This seems like a great idea for the king and queen but LOUSY for the worker. However, if you look more closely at the family tree of these social animals, you will find the workers are closely related to the king and queen and to each other. At that point, you begin to see the workers are raising their sisters and brothers. By helping their parents produce more sisters and brothers, their own genes are represented in their millions of siblings. At this point, it begins to make more sense for a worker to stay in the colony and raise siblings rather than trying to reproduce. The chances of a single worker being able to survive, find a mate, found a new colony and have offspring are virtually zero. By now, you know that biologists name everything. So what would you call a situation where someone hangs around their parents and raises their siblings (kin)? Kin selection. Remember, these are adaptations. The individual doesn't consciously decide to give up its reproductive rights. This behavior has evolved over time because individuals who carried out this behavior left more copies of their genes (as siblings) than individuals who didn't. Check out the Attenborough video on the amazing architecture of termite mounds and termite societies. You will find this fascinating Youtube video at: http://www.youtube.com/watch?v=xGaT0B__2DM
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CONCEPTS STUDY QUESTIONS FOR EPISODE 5: 1. Describe the zonation or stratification that exists in grasslands. Describe the plant components, processes and animals found in each layer.
2. Describe the social castes of termites.
3. What is necessary for an organism to be successful in an evolutionary sense?
4. Explain the concept of kin selection. Using this concept, briefly explain why worker termites care for their siblings instead of having their own offspring.
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VIDEO STUDY QUESTIONS FOR EPISODE 5 - Seas of Grass: 1. Describe the characteristics of grasses. How many species of grasses exist? How are grasses pollinated?
2. Where is the growing part of the grass plant? How does this allow grasses to survive hardships? Identify these hardships.
3. Identify the diet of the following animals: a. lizards
b. mantis
c. spiders
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Locator: Savanna, Brazil 4. Describe the giant anteater. a. What is its diet?
b. What is its defense against predators?
c. How does the giant anteater collect termites?
d. How are they protected from the cold?
e. Why are the young carried on the back of the adult?
5. The following predators are associated with termites and their mounds. Give a brief description of each animal and describe their diet. a. beetle larvae
b. giant armadillo
c. Oxymitras mouse
d. carnivorous ants
6. Describe the soldier termites. What is their function?
7. Grass is composed primarily of cellulose, which is very difficult to digest. What adaptation allows the termites to digest cellulose?
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8. Describe the grass cutting ants. How do these ants deal with the problem of cellulose? What do they eat? Describe their nest. How do they tend their gardens?
Locator: Grasslands, Brazil. (The grasslands shown in the video are from southern Brazil and Argentina. These are called the pampas.) 9. Since grasslands have no trees, how do the birds that live on the grasslands proclaim their territories?
10. Briefly describe the following grassland inhabitants, particularly their diet. a. seriema
b. tapir
c. savanna deer
d. armadillo
e. tegu lizard
11. Identify the two places where grassland birds build their nests.
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12. Describe the nesting habits of the following birds that live on the grasslands. a. flicker
b. kestrel
c. burrowing owl
d. plover
e. tinamou
13. Explain why the young burrowing owls are at risk. When do they start developing their flight feathers?
14. Describe the territorial displays of the plovers.
15. What does the tinamou do to hide its eggs from predators?
16. Describe the nesting habit of the rhea.
17. Which parent cares for and protects the young rhea chicks?
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18. Describe the maned wolf. What does it eat? How does it mark its territory?
19. Why are trees not found on the pampas of Argentina or Brazil?
20. Describe the effects of the dry season on these grasslands.
Locator: Llanos, Venezuela species mentioned in this section: capybara, caiman 21. Why do these grasslands flood during the rainy season? How long are they flooded?
22. Which organisms do well in the flooded conditions?
23. What is the effect of the flooded conditions on burrowing rodents?
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Locator: Prairies of North America 24. The main source of water during the rainy season of this grassland is ______________. The temperatures during the winter get as low as ________________________.
25. How do the following animals cope with the winter conditions? a. ground squirrels
b. prairie dogs
c. prairie chickens
d. pocket gopher
26. During the winter, where does the grass plant store its food and nutrients?
27. Describe the following inhabitants of the prairie and explain how they survive the winter months. a. bison
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b. pronghorn
c. coyote
28. What two winter conditions are responsible for the deaths of many animals?
29. Describe the aggressive behavior displays of the coyotes.
30. How do rattlesnakes survive the winter?
31. Describe the courtship and mating rituals of the prairie chicken.
32. What is a prairie dog town?
33. When do the prairie dogs mate and have young?
34. Describe the mating behavior of the bisons. What is the gestation period for bison?
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35. Why are the prairie dogs considered to be "good farmers"?
36. What do prairie dogs do when they spot predators or intruders?
37. What are ruminants? What animals are ruminants?
38. What two factors are responsible for the comparatively small amount of rainfall received by North American prairies?
Locator: Steppes, Russia 39. Where are the steppes located?
40. Describe the saiga antelope and its adaptations to the cold steppes.
41. What catastrophic condition occurs regularly in the steppes?
42. Explain the extraordinary method of reproduction found in the saiga antelope.
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Locator: Tropical grasslands, Africa 43. How are the tropical grasslands in Africa different from the other grasslands?
44. Where do trees grow in the tropical grasslands of Africa?
45. Why is fire a major factor in preserving grasslands?
======================================================================= ADDITIONAL INFO. In the video, Attenborough does not distinguish between the two types of African grasslands: the veldts of South Africa and the savannas of East Africa. This information is covered in his book, pages 131-133. The grassland shown in the video is the savanna of East Africa. The savanna of East Africa is the only remaining large grassland in Africa. These grasslands are a mixture of tall and short grasses with scattered tough thorny trees and shrubs. Acacia trees, like the one in the video, are drought-resistant and have a relationship with many animals. Certain animals, especially gazelles and elephants, eat the fruit. The tough hard seeds pass unharmed through their digestive systems and are dropped onto soil. In fact, some Acacia seeds cannot germinate unless they have passed through the digestive tracts of elephants, where digestive juices break down the tough outer seed coat. The veldt of South Africa used to be extensive. These rolling plains were rich in grasses and there were no trees. European settlers in the early 1800s reported extensive herds of antelope and other large grazing herbivores. One naturalist in 1880, according to Attenborough, estimated one migrating springbok herd alone contained one million individuals (p. 131). Through extensive hunting and habitat loss, these great herds dwindled. Some species, such as the quagga (a type of zebra) were totally wiped out. By 1883, the quagga was extinct. Today, the grazing herds and the natural grassland are both a tiny fraction of their original size. ======================================================================= 46. Where, in Africa, are the grasslands located? How old are these grasslands?
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47. Which grassland has the greatest variety and largest number of grass-eating herbivores in the world?
48. The animals have evolved with the grasslands, ensuring that almost every part of the grass is eaten by something. These vegetarians in turn are eaten by predators. What are the prey species of the following predators? a. serval
b. lions
c. hunting dogs
d. cheetahs
49. Describe the mating and territorial behavior of dik-diks.
50. What do dik-diks eat? How do they elude predators?
51. What do impala eat? How do they elude predators?
52. Describe the mating and territorial behavior of impala.
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53. What do wildebeests eat?
54. Why do the wildebeest have to migrate constantly?
55. Describe the mating and territorial behavior of wildebeest.
Locator: Sudan 56. Describe the lifestyle of the people who live in eastern Sudan.
57. Why are the kob antelopes so important to the survival and well being of the people of Sudan?
58. Describe the migratory route of the kob antelope.
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59. How many kobs migrate each year? How many are killed by the Murle people?
60. Summarize the characteristics of grassland, particularly the hardships that the grass can survive.
61. How does a grassland become a desert?
======================================================================= ADDITIONAL INFO. Even though Attenborough does not examine Australia in this videotape, there are four types of Australian grasslands. These are quite extensive, covering close to 47% of the continent. Much of this is due to prolonged, periodic droughts, which trees cannot withstand. There are tropical savannas in the north, and dry grasslands that surround much of the arid interior. The grassland mammals are marsupials, such as marsupial mice. The large grazing herbivores are kangaroos and wallabies. Wombats are the marsupial burrowing mammal. There are numerous birds, many nomadic. Large flightless emus are found in small groups in these grasslands. Here, the male emu, like the rhea, guards his eggs from multiple females and rears the young. Lizards and snakes are especially abundant in these Australian grasslands. [So what are the other two Australian grasslands? Lowland native grasslands and subalpine grasslands.] References: Curry-Lindahl, Kai. 1981. Wildlife of the Prairies and Plains. Henry N. Abrams, Inc., New York. Smith, Robert Leo. 1992. Elements of Ecology, 3rd ed. HarperCollins, New York.
=======================================================================
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62. After watching Video Episode 5, use the information in the video episode and the study guide to compare the major grasslands of the world by location, special climate features, and species that live there. Major Grasslands
Location
Savanna
South America
Climate
Pampas
Llanos
Prairies
Steppes
Veldt
Savanna
East Africa
Australian grasslands
Australia
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LIVING PLANET EPISODE SIX MATERIAL FOR YOU TO COVER Read the CONCEPTS section in the study guide for episode 6. Answer the Concepts Study Questions. Watch Video Episode 6 – The Baking Deserts. Answer the Video Study Questions.
EPISODE 6 LEARNING OBJECTIVES To become acquainted with: 1. Characteristics of deserts 2. Ecology of deserts: location, climate, characteristics, life forms and adaptations 3. The differences between major deserts, including location, climate, life forms and specific adaptations • Sahara • Arizona desert (Sonoran Desert) • Kalahari • Namib 4. Adaptations of plant life that allow them to live in desert conditions 5. Adaptations of animal life that allow them to live in desert conditions 6. Adaptations of animals that live in the sand dunes
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CONCEPTS FOR EPISODE 6: THE BAKING DESERTS CHARACTERISTICS OF DESERTS Although there are many types of deserts, certain features are common to all. Rainfall is scarce. The rate of evaporation is very high, exceeding the rate of rainfall. Temperatures fluctuate widely within a 24-hour period, with cool nights and hot days. The ground soaks up heat during the day and then releases it quickly into the air at night. In general terms, a desert is dry. Generally, any place that gets less than 10 inches of rainfall per year (25 cm/year) is a desert. Based on total annual rainfall, deserts range from semideserts (6-15 in/year) to true deserts (less than 5 in/yr) to extreme deserts (less than 3 in/year). In some deserts, rain may fall only once every 18 months or 2 years. Rainfall is typically sporadic, with long dry spells punctuated by heavy storms. Cloudbursts are common in some deserts, with rainfall occurring faster than the soil can absorb it. This results in rapid surface runoff and flash flooding in dry streambeds. Based on temperature, deserts vary considerably but are always hot for at least part of the year. There are hot deserts, like the Sahara, which are warm throughout the year. Some are cold deserts, such as the Great Basin Desert, with temperatures falling below freezing during the winter. Cold deserts are cold for part of the year. ALL deserts experience great swings of temperature over a 24-hour period. Perhaps another way of looking at hot deserts versus cold deserts is to consider precipitation. The main form of precipitation in a cold desert is snow, while hot deserts experience precipitation as rain. Desert soils are typically poor in organic matter (humus) even though there may be high levels of minerals. Vegetation is sparsely scattered, due to the lack of water. The salt content may also be quite high. This is due to evaporation, which removes water from the soil but leaves the salt behind. PROBLEMS AND ADAPTATIONS Desert plants and animals have similar problems. Water problems can be summed up as: how to get water when it is available, how to keep water, and how to survive long periods without water. Food and heat are also problems. See the video for plant and animal solutions. Problem 1: How To Get Water Most plants get their water through their roots and desert plants are no exception. As a rule of thumb, most plants have about the same amount of roots below ground as they have stems and leaves above ground. Desert plants, however, have more extensive root systems, typically 2-6 times more roots than visible stems and leaves. There are three general strategies used by desert plants to get water: (1) Many plants have deep root systems, which penetrate the ground for several meters, often to the water table. This allows them access to water that is far below the surface. (2) Other plants have shallow roots that spread out for many meters around the plant and take up almost every drop of soil moisture close to the surface. (3) Instead of relying on roots, some plants get their water from the air. These plants absorb fog droplets across their leaves. This gives them access to water that is not available to other plants but there has to be dependable fogs.
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Problem 2: How To Keep Water Organisms that live in the desert live in an area where evaporation exceeds precipitation. In other words, more water is lost by evaporation than replaced by rainfall. Controlling water loss is a major problem. Watch the video for examples of these adaptations. (1) Sunken stomata. Plants must have stomata (openings) in their leaves for gas exchange. However, this also allows water to evaporate. Many plants have sunk their stomata into pits. (Remember the conifers. They use the same strategy.) (2) Close the stomata during the hot daytime and open them at night when it's cool. (3) Get rid of the thin leaves and move photosynthesis and the stomata to the thick stem. (This is one method used by cacti. Look for the saguaro cactus in the video.) Problem 3: How To Survive Long Periods Without Water Again, there are many strategies used by plants to survive for long periods without water. Some of these are mentioned in the video. (1) Many plants store water internally. When the rains come, the plant soaks up tremendous amounts of water, which is then stored somewhere in the plant body. (2) One technique is drought avoidance. These are ephemeral plants, which survive drought in the form of seeds. When the rains come, the seed germinates, grows and reproduces within a short time. As the normal desert conditions return, the adult plant dies, leaving only its seeds behind. (3) Some plants are drought-deciduous, losing most of their leaves during the dry season. New leaves are grown when the rains come. The creosote bush uses this strategy. (4) Some plants are drought-tolerant and are able to withstand desiccation (drying out). One example is the resurrection plant, which becomes brown when it dries out totally, yet becomes green and active when water is available. Problem 4: How To Handle The Heat Bodies absorb heat and there is a lot of heat in the desert. The plant or animal has to be able to (1) tolerate the heat, (2) modify some part of its body to minimize excess heating, or (3) avoid the hot parts of the day. Look for examples in the video. Problem 5: How To Acquire Food Plants are able to make their own food through photosynthesis. For animals, the availability of food can be variable - lots of food after the rains and then long periods of little food. Many animals, such as desert rodents, store food. Other animals, such as birds and larger grazing animals, have the mobility to move about the desert, seeking the spots where food is more abundant. Ectotherms have a distinct advantage over endotherms, since endotherms require more daily food to fuel their internal reactions. Hence, there are lots of desert ectotherms. References: Smith, Robert Leo. 1992. Elements of Ecology, 3rd ed. HarperCollins, NY. Vankat, John L. 1979. The Natural Vegetation of North America. Wiley & Sons, NY. Wagner, Frederic H. 1980. Wildlife of the deserts. Harry N. Abrams, Inc., NY.
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CONCEPTS STUDY QUESTIONS FOR EPISODE 6 1. Describe the characteristics of deserts (climate and soil).
2. Explain the difference between hot and cold deserts. Give an example of each.
3. Describe adaptations used by desert plants to obtain water.
4. Describe adaptations used by desert plants to keep water once they get it.
5. Describe adaptations used by desert plants to survive long periods without water.
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6. Describe adaptations used by desert plants and animals to deal with the heat.
7. Describe adaptations used by desert animals to obtain food. (Note: You may want to come back to this question after viewing this episode.)
8. Compare the food needs of desert ectotherms and endotherms.
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VIDEO STUDY QUESTIONS FOR EPISODE 6 1. As you go through the episode, keep track of the major deserts of the world described by Attenborough and their geographic location.
======================================================================= ADDITIONAL INFO. You will find fascinating information about the Atacama Desert at: http://worldwildlife.org/ecoregions/nt1303 For example, there are places in the Atacama Desert where there is NO recorded rainfall and places where decomposition does not occur because there is no moisture. ======================================================================= Locator: Sahara desert 2. Describe the Sahara desert -- its boundaries, size, daily temperatures and maximum recorded temperature.
3. What evidence exists to suggest that the Sahara was once grasslands instead of desert?
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4. When did the change from grassland to desert occur? Why did the change occur?
5. What other piece of evidence supports the belief that the Sahara desert used to be grassland?
6. Describe the ancient cypress that still exists in the Sahara. How old is the plant? How does it survive? Explain why its seeds will never produce seedlings.
7. What climatic change caused the formation of the Sahara Desert? Were other areas affected by this change?
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8. What deserts lie north and south of the equator?
======================================================================= ADDITIONAL INFO. Most deserts occur within two distinct belts north and south of the equator, between 15 degrees and 35 degrees N and S latitude, centered between the Tropic of Cancer (23½ degrees N latitude) and the Tropic of Capricorn (23½ degrees S latitude). Attenborough describes one major force that creates desert conditions - the movement of air masses that are dry because they have lost their moisture to other parts of the land. There are other forces that create dry air. As air rises up tall mountains, the air cools and rain falls on the mountains. As the air currents pass over the mountains and descend, there is little moisture. Many deserts, such as the Great Basin Desert, lie in the rain shadow of mountains. Other deserts lie in the interior of continents. By the time air gets to the interior, it has been stripped of its moisture. Their remote location is responsible for the formation of the Gobi Desert, the interior of the Sahara and the central deserts found in the interior of Australia. ====================================================================== 9. When are animals active in the Sahara? Why?
10. Be familiar with the different animals that live in the Sahara. Know the diets for the animals listed with a star (*). a. striped hyena
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b. fennec fox*
c. gecko
d. jerboa*
e. gerbils*
f. caracals*
g. scorpion*
h. black widow spider*
i. wolves*
11. How are the wolves in the Middle Eastern deserts different from other wolves?
12. What strategy is used by these animals to avoid the heat?
13. Which animals are active during the day?
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Locator: Desert, Arizona 14. When is the Gila monster active? Is it active throughout the day or at special times?
15. Describe the Gila monster. What is unusual about the Gila monster? What does it eat?
======================================================================= ADDITIONAL INFO. At one point, it was thought there were only two poisonous lizards: the Gila monster and the Mexican beaded lizard, found also in the southwestern United States and Mexico. New information suggests that several other lizards may be poisonous, including the Komodo dragon. Website: http://www.livescience.com/animals/051117_lizard_venom.html ======================================================================= 16. What does the tortoise eat? How does it survive the desert heat?
17. How do birds, such as the poor wills, survive the extreme heat of the desert? How does their method of cooling compare to the method used by most mammals?
Locator: Desert, Africa 18. How does the sand grouse regulate its temperature during the day? What does it eat? How does the male supply water to the young?
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Locator: American Desert 19. How does the roadrunner of the Arizona desert supply its chicks with water? What does it eat? How does the roadrunner protect the young during the heat of the day? How does it shade itself?
20. How does the ground squirrel of the Namib desert protect itself from the heat of the day?
21. How do many desert animals, such as the hedgehog, fennec fox and American jackrabbit, cool themselves?
22. Describe the adaptations of the Dorcas gazelle to desert life.
Locator: Death Valley [located in the Mojave Desert] 23. How hot does this desert get?
[Note: This is measuring ground temperature, not air.]
24. How do the animals cope with the heat?
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26. Describe the creosote bush and its adaptations to desert life.
27. What is the oldest living organism? How old is it?
28. How infrequent is rain in the Mojave desert?
Locator: Desert, Arizona 29. Describe the cactus family. Where are cactus found?
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30. Describe the saguaro cactus and its adaptations to desert life.
31. What prevents other animals from using the water reserves of the saguaro cactus?
Locator: Kalahari desert 32. How do the Bushmen of the Kalahari desert find water during the dry season?
Locator: Namib desert 33. When can patches of grass be found in this desert? How long do they live?
34. Describe the Welwitschia plant and its adaptations to desert life. Why is it considered to have traits of both conifers and flowering plants?
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35. What is unusual about the Namib Desert? How do animals, such as the darkling beetles, take advantage of the fog?
36. Describe the changes that occur to the stems and seed heads of dead plants when rain finally does come. Explain how seeds are dispersed.
Locator: Arizona desert 37. Describe the reproductive cycle of the spadefoot toads.
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38. How do fairy shrimp get into these desert pools?
39. Describe the two different forms of the tadpoles of the spade foot toads found in the desert. How does this ensure survival of at least some offspring under different conditions?
======================================================================== ADDITIONAL INFO: In his book, Attenborough elaborates on the two types of tadpoles. Carnivorous tadpoles have the advantage if it doesn't rain again. Since they are eating meat, they grow faster. Thus, they have a higher chance of making it to the adult stage before the pool dries up. On the other hand, if it does rain again, the pool becomes muddy. It becomes hard for the carnivorous tadpoles to see their prey. The vegetarian tadpoles have an advantage in this situation because they don't need to see to eat algae. In this situation, they grow faster and have a better chance of becoming adults. (pp 156-159) David Pfennig (when he was at UT as a graduate student) studied this system. He found that a carnivorous tadpole can tell by taste whether or not a vegetarian tadpole is a brother or sister. If the vegetarian tadpole is a sibling, then the carnivorous tadpole will NOT eat it. If the vegetarian tadpole is NOT related, then the carnivorous tadpole has lunch. This is another example of an animal foregoing a personal benefit (a meal) so that a relative will have a better chance to survive and reproduce. Thus, this is another case of kin selection. ========================================================================
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40. How are sand grains formed?
41. Explain how sand dunes are formed. How do sand dunes move?
======================================================================= ADDITIONAL INFO. Not all sand dunes move. If the wind blows mainly from one direction and is relatively constant, the sand is blown up one side of the dune and down the other. Thus, the sand dune moves. As Attenborough explains in his book on page 160, sand dunes do not move if the wind is constantly shifting, blowing first in one direction and then in another. These sand dunes are relatively stable and become named landmarks. ======================================================================= 42. What are the difficulties of moving on top of sand?
43. How have some animals, such as the sidewinder and Namib fringe-toed lizard, solved the problem of coping with the surface of hot, shifting sand?
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44. What is the advantage of burrowing in the sand? What are the problems with burrowing?
45. Describe the blind skink. What adaptations does the blind skink have for living in the sand?
46. Describe the golden mole. Does it have eyes? Does it have ears? What is its diet?
======================================================================= ADDITIONAL INFO: The golden mole hunts insects on the surface of the sands. When s/he's full, s/he swims into the sand about a foot down and becomes torpid, reducing the energy demands. After about 19-20 hours, it's time to hunt again. How can the mole survive being buried in the sand for so long? The uniform size of the sand grains allows air flow through the spaces between the grains. That way, they get enough oxygen to breathe. =======================================================================
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Locator: Sahara 47. Who are the Tuareg? How do they survive their trips through the Sahara desert?
48. Describe the camel and its adaptations to desert life.
49. How are oases formed? What types of animals and plants are found in these areas? Why are the oases under constant threat from the surrounding desert?
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50. Compare the major deserts discussed in the video with respect to location, variation in climate, organisms that live there, and specific adaptations. Major Deserts
Sahara Desert
Arizona desert (Sonoran Desert)
Kalahari Desert
Namib Desert
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LIVING PLANET EPISODE SEVEN MATERIAL FOR YOU TO COVER Read the CONCEPTS section in the study guide for episode 7. Answer the Concepts Study Questions. Watch Video Episode 7 – Community in the Sky. Answer the Video Study Questions. Note: If you are using the Living Planet DVDs, this episode is called “The Sky Above.” The name used in the streaming videos is “Community in the Sky.”
EPISODE 7 LEARNING OBJECTIVES To become acquainted with: 1. Characteristics and layers of the atmosphere 2. Human effects on the atmosphere 3. The carbon cycle 4. The water cycle 5. Comparisons between bird wings, bat wings and insect wings 6. Various atmospheric conditions: tornadoes, hurricanes, etc. 7. Ways that organisms use the wind for transportation 8. Gliding and animals that use gliding 9. Powered flight and animals that use powered flight 10. The concept of lift 11. The problems of takeoff and various solutions 12. Thermals and how organisms use thermals 13. Adaptations of birds to flight 14. Echo-location and organisms that use echo-location 15. Migration
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CONCEPTS FOR EPISODE 7: Community in the Sky WINGS Three groups of living animals can fly: the insects, the birds, and the bats. Each of these animals has evolved wings, but the wings differ in structure. In insects, the wings are outgrowths of the rigid covering of the body. Most insects have two pairs of wings (for a total of 4). The wings are made of a thin membrane reinforced by struts called veins. The wings flap in a figure-eight motion, generating lift as the wings move down and forward. During the recovery stroke, the wings move up and back. It takes a high level of nervous system control to coordinate all four wings so that they do not smack into each other during flight. In both birds and bats, one pair of legs, the forelegs, has evolved into the wings. Insect wings did not evolve from legs. They probably evolved from small flaps used by terrestrial insects to soak up heat to raise their body temperature, or by aquatic insects to absorb oxygen from the water. In birds, the feathers of the wing form the surface that generates lift. The bones of the wing are strong, with some of the fingers fused together for additional strength. As the wings flap, they move in a figure-eight motion. During the downstroke the wing moves down and forward, generating lift. During the upstroke, or recovery stroke, the wing moves up and back. As explained in the video, the feathers can slide over each other, so the shape of the wing surface can be changed. Insects and bats cannot change their wing shape. In bats, the wing surface is formed by a membrane of skin that is stretched between the neck and the thumb, from there to the third, fourth and fifth fingertips, then to the feet, and from there to the tail. The fingers are very long, to provide support for the wing membrane. The tip of the wing travels in an oval shape instead of a figureeight as the bat flaps its wings. The wing membrane is often used to help the bat catch insects, serving as a scoop used to bring the food to the bat's mouth.
References: Grzimek, Bernhard, ed. 1984. Grzimek's Animal Life Encyclopedia. Volume 2: Insects and Volume 11: Mammals II. Van Nostrand Reinhold, NY. Harris, C. Leon. 1992. Concepts in Zoology. HarperCollins, NY. Trewartha, Glenn T. and Lyle H. Horn. 1980. An Introduction to Climate. 5th ed. McGraw-Hill, NY. Williams, Jack. 1992. The Weather Book. Vintage, NY.
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THE ATMOSPHERE The atmosphere is an envelope of gases that blankets the Earth. The most common gases in the atmosphere are nitrogen (78%), oxygen (21%), argon (1%) and carbon dioxide (0.04%). The amount of water vapor, also a gas, varies considerably, with concentrations of almost zero in desert and polar regions to 3% to 4% in the hot humid jungles. The gases are distributed in a number of layers. Most of the gases are found close to the surface of the earth, in the troposphere. The troposphere extends to 5 miles above the surface. (Watch Attenborough explore the troposphere in the high altitude balloon. By the time he reaches the edge of the troposphere, he has to use an oxygen mask to breathe, because the amount of gases decreases as he ascends.) The troposphere is the layer in which weather occurs: winds, storms, and air currents such as the jet stream. Above the troposphere lies the stratosphere. It extends from 5 to about 30 miles above the ground. The stratosphere is poor in gases compared to the troposphere, but it does contain an important gas that is normally missing in the layer below: ozone. The ozone is formed when oxygen molecules are struck by sunlight. The stratospheric ozone absorbs rays of ultraviolet (UV) light and prevents most of them from reaching the surface of the planet. UV light has a high energy level. When a ray of UV light strikes a living cell, it rips into the important biological molecules of which the cell is composed. It can damage the genetic material of the cell, resulting in changes that can lead to cancer. Human activities have damaged this protective layer of stratospheric ozone. Chlorofluorocarbons (CFCs) are chemical compounds used in air conditioner coolants such as Freon. They have many other uses as well. When CFCs leak into the atmosphere, they are carried up to the stratosphere where they break down the ozone molecules. Weakening the stratospheric ozone layer may lead to an increase in skin cancer rates in people and, more seriously, a disruption of food chains as the increased amount of UV light seriously affects plants, algae, and animals. The 1987 Montreal Protocol, an international plan to reduce or ban the production of certain ozonedestroying compounds, mandates the reduction of CFCs and other compounds manufactured in developing countries. As of 2016, there is some evidence that the levels of ozone in the stratosphere are finally increasing. You can find more information at: https://www.sciencedaily.com/news/earth_climate/ozone_holes/ Above the stratosphere is the mesosphere (30 to 50 miles above the surface). The main feature of the mesosphere is a serious drop in temperature to almost -100° C, which is colder than any temperature ever recorded on the surface. Water vapor freezes, forming ice crystal clouds that may be visible after sunset if conditions are just right. The shooting stars you see are usually meteors that are burning up as they go through the mesosphere.
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The ionosphere is the layer above 50 miles, where solar radiation ionizes atoms; hence, the name and the formation of the aurora borealis (northern lights) and aurora australis (southern lights). The auroras are brilliant flares of colored light that flash and flicker silently across the clear polar skies. They are formed when charged atoms emitted by the sun and carried to Earth on the solar wind hit the surface of the atmosphere and collide with the gases there, emitting flashes of light. Sadly, here in Austin, the northern lights are rarely visible. ================================================================== CLARIFICATION: The ozone effect is NOT the same thing as the greenhouse effect. They both involve the atmosphere but the causes are different. Both issues are part of the debate when people talk about global climate change. ==================================================================
GLOBAL WARMING One of the most important gases present in the troposphere is carbon dioxide. Carbon dioxide lets in light from the sun, but traps heat trying to return to space. Thus, the concentration of carbon dioxide in the troposphere, along with a few other gases such as methane, determines the temperature at the surface of the planet. The more carbon dioxide there is in the troposphere, the more heat is trapped and the higher the surface temperature will be. This process is called the greenhouse effect. Carbon dioxide is released to the atmosphere by all organisms as they use oxygen to burn fuel to run the biochemical reactions of their bodies. It is removed from the atmosphere by plants and algae during photosynthesis. In a real sense, the producers determine the carbon dioxide content of the atmosphere, and through that, the surface temperature. Any disturbance to the balance of carbon dioxide release and removal will alter the surface temperature. Human activities over the last 200 years have altered that balance. Fossil fuels, such as oil and coal, were formed from an incredible number of photosynthesizers that picked up carbon dioxide and stored it in their tissues millions of years ago. Burning fossil fuels releases a large amount of carbon dioxide to the atmosphere each year. Clearing the land of forests and other plant communities for cropland and dwellings decreases the removal of carbon dioxide by plants, so more carbon dioxide stays in the atmosphere. The combined effects of fossil fuel burning and land clearing is global warming, the warming of the surface of the planet. Global warming may have serious consequences. It will change the patterns of climate and weather around the world. Areas that used to receive enough rainfall to produce crops may become dry, leading to disruption in the food supply. Other areas may receive more rainfall than normal, leading to flooding. The plants and animals of all the communities may be unable to adapt quickly to the changes in climate and temperature. Thus, many organisms may go extinct. The ice of the polar regions may melt, raising sea level worldwide. Scientists who study global warming may disagree © Speer, Maxim and Strong
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about the details but they all agree that we should be deeply concerned about possible impacts on the planet. Global warming may also be altering migratory patterns, as discussed here. http://news.nationalgeographic.com/news/2005/11/1122_051122_winter_birds.html You can find more up-to-date information about global warming and climate change at these websites: • http://climate.nasa.gov/ • http://earthobservatory.nasa.gov/Features/GlobalWarming/page2.php • http://www.noaa.gov/climate • https://www.ncdc.noaa.gov/monitoring-references/faq/global-warming.php THE CARBON CYCLE If you read the section above carefully, you will notice that this is another nutrient cycle: the carbon cycle. Some carbon is found in the atmosphere, in the form of gases such as carbon dioxide. Some carbon is found in the living bodies of plants, animals and organisms in the form of molecules such as carbohydrates, fats, proteins and nucleic acids (DNA, RNA). Some carbon is found in sedimentary rocks or in fossil fuels. The following diagram is a brief overview of how carbon moves through living organisms.
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There is another alternate pathway to the carbon cycle that takes more time to recycle the carbon. In this pathway, carbon is stored in geological formations, such as sedimentary rocks (like limestone) and fossil fuels (oil, gas, coal and peat).
================================================================== Additional Information about the carbon cycle: Several students have asked for more information about the carbon cycle. If you feel that you already understand the carbon cycle, then skip on down to the water cycle. Otherwise, here goes! Let’s start with a closer look at the "Brief Overview of carbon cycle" on this page. First, all organisms have cells and cells undergo respiration in which sugar is burned as fuel. In the process, most give off carbon dioxide as a gas. This applies to photosynthesizers (producers) and consumers and decomposers. So, as almost all organisms go through their daily life, carbon dioxide gas is added back into the atmosphere by these organisms. (For example, look at us. When we exhale, carbon dioxide goes back into the atmosphere. As your houseplant undergoes daily activity, it too adds carbon dioxide gas back into the atmosphere.) All living things need carbon in their cells to make carbohydrates, fats, proteins and nucleic acids. So, somehow, organisms need to get the carbon out of the atmosphere (in the form of carbon dioxide) and into their bodies so they can make these molecules that they need. That's where the producers come in. Producers (plants, cyanobacteria, etc.) take carbon dioxide out of the atmosphere and, in the presence of sun and water, convert carbon dioxide into sugar (carbohydrates). This process is called photosynthesis.
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Almost immediately, the cells of the producer use some of that sugar as fuel. (This process is cellular respiration). The excess sugar goes into building plant bodies. (To make it simple, I'm just going to talk about plant producers. The same will apply to any producer.) So, now the plant is building its body – its leaves, flowers, fruits, roots, stems, whatever. As these activities are taking place, the plant cells are using carbohydrates as fuel -- and giving off carbon dioxide gas. Now the consumers (such as animals) come along and eat the plant body. They are eating the plant tissues that contain carbohydrates, proteins, nucleic acids and fats. In this way, carbon now leaves the plant body and enters the animal body. The animal processes what it can (the rest becomes waste products) and now the carbon becomes available to the animal cells. In the process, carbohydrates are used as fuel by the animal cells – which form carbon dioxide gas in the process. Throughout a plant’s life, parts of the plant fall off or are broken. Limbs, grass stems, leaves, etc. fall off the plant and often onto the ground. Animals give off waste products (urine, feces) and also die. As these waste products, dead plant parts and dead animals become available to the decomposers, the decomposers start using these things to provide their bodies with carbohydrates, etc. As the decomposers (bacteria, fungus) live, their cells are also using their new carbohydrates as fuel for their cells – which returns carbon dioxide gas to the atmosphere. Now, let's go to the alternate carbon pathway. Students have asked the question: "Is the relationship between decomposers and respiration similar or the same as the relationship between decomposers and respiration in the alternate Carbon Cycle?" The answer is yes. This cycle just adds another layer to the picture. This part occurs if the decomposers don't get a chance to break down all of the plant and animal bodies before they are covered with sediments and turned into rock. (Remember the giant horsetails that were turned into peat, covered with sediments and became coal? Unit 3?) So, if these plants/animal parts do not decompose quickly, they may be converted into sedimentary rocks or fossil fuels. As the rocks are broken down (through wind, water activity and human mining) and fossil fuels are burned in our engines, the carbon trapped in the rocks and fossil fuels gets added back into the environment. Here are some quick concept check questions. (1) How does carbon leave the atmosphere? (2) How does carbon enter the atmosphere from plants, animals and other organisms? (3) Where is carbon stored? (4) How does carbon stored in the bodies of organisms return to the atmosphere? (5) How does carbon stored in sedimentary rocks or fossil fuels return to the atmosphere? ================================================================== © Speer, Maxim and Strong
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THE WATER CYCLE Another important gas in the troposphere is water vapor. This gas is the source of all the precipitation that falls on the planet's surface. Precipitation means rain, snow, sleet, hail or any other form of water falling from the sky. The water cycle is the process by which water vapor and precipitation are converted endlessly from one form into the other. The water vapor in the troposphere forms as liquid water evaporates from the surface of the oceans, bodies of fresh water, and plants. As the air is heated by the sun, it rises, carrying the water vapor aloft. But as the air rises, it cools. Cool air cannot hold as much water vapor as warm air, so the water begins to condense to form small droplets of liquid water. If the droplets become large and heavy enough, they drop from the sky as rain. The rain will eventually return to the ocean. It may return in a number of ways. It may fall on the ocean itself, or it may flow over the surface of the land into the rivers which carry it to the sea. Or it may soak into the ground, joining the pools of water underground that flow very slowly towards the rivers and the sea. Here's a diagram of the short version of the water cycle:
WEATHER: TORNADOES AND HURRICANES The atmosphere is a place full of change. Air is moving everywhere as winds rush from place to place. The winds tend to flow from areas of high air pressure to areas of low pressure, and the earth's rotation gives the whole system a twist, so that the winds tend to spiral into the low pressure areas. If a low pressure area is strong, the winds speed into it at high velocities. A very strong low pressure area generates winds with speeds of over 75 miles an hour, at which point the system is called a hurricane. The strongest winds of all are not found in hurricanes, however. They are found in tornadoes, where wind speeds in excess of 300 mph have been recorded (one can assume by a "foolhardy" person, as Attenborough might say). Tornadoes are found in association with intense thunderstorms. At the core of the thunderstorm is a column of © Speer, Maxim and Strong
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rising air that twists in a spiral as it rises. It is this area of the storm that gives rise to tornadoes. A tornado consists of a small but violent column of rapidly spiraling air called a vortex. Scientists are not sure whether air sinks inside the vortex, or exactly how the vortex forms. They are sure, however, that the vortex acts like a giant vacuum cleaner hose, sucking up air from near the ground, and any cows or cars that may be in the way as well. The air is carried up rapidly, and the traveling cows and cars carried with it are deposited some distance away.
MONARCH BUTTERFLIES AND MIGRATION The migration of monarch butterflies has been intensively studied in the years since Attenborough produced LIVING PLANET. The monarch butterflies described in the video are found east of the Rocky Mountains. Monarch butterflies are the only type of butterflies that make long, two way migrations every year. The total journey can be up to three thousand miles. Individuals only make the round trip once. The next journey will be made by their distant descendents (their great-grandchildren). Not every monarch butterfly migrates. The ones that emerge from their chrysalides in the summer usually live only a few weeks. The monarch butterflies that emerge in late summer or fall are different. These are the monarchs that will migrate to Mexico to overwinter and then begin the return migration north in the spring. The monarchs will mate, lay eggs and die during late spring and summer. [Please note: not all butterflies make it back to their starting point. Many mate and lay their eggs along the way. The next generation may continue migrating north.] Several generations later, their descendents will leave in large numbers to migrate southward to the same wintering roosts. More information is available about monarch butterflies from Monarch Watch, a research project at the University of Kansas. Visit their web site at: http://monarchwatch.org. Thousands of volunteers monitor the monarch butterfly migrations every year. You can also get information about citizen monitoring projects involving monarch butterflies (and other species) at www.learner.org/jnorth/. Texas Parks and Wildlife biologists monitor monarch butterflies and encourages the public to report monarch butterfly adults or larvae to their hotline (1-800-468-9719 or 512-326-2231 in Austin). Watch your local paper in the fall for news stories about monarch butterflies. So, what about those monarch butterflies born west of the Rocky Mountains? They migrate to coastal California and spend the winter in trees.
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Map Credit: http://www.kindermagic.com/backyard_bugs.html
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CONCEPTS STUDY QUESTIONS FOR EPISODE 7 1. Describe and compare the wings of insects, birds and bats.
2. Describe the chemical composition of the atmosphere.
3. Describe the layers of the atmosphere including any special characteristics of each layer.
4. Explain how damage to the ozone layer occurred and describe the consequences for living things.
5. Describe the normal greenhouse effect.
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6. Describe the sources of additional atmospheric carbon dioxide produced by humans and explain how this has affected the rate of global warming.
7. Describe the consequences of global warming.
8. List and define the processes involved in the carbon cycle. Diagram the cycle and explain how the processes are related.
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9. List and define the processes involved in the water cycle. Diagram the cycle and explain how the processes are related.
10. Explain how hurricanes and tornadoes are formed.
11. Describe the migration patterns of monarch butterflies.
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VIDEO STUDY QUESTIONS FOR EPISODE 7 1. What is the impact of gravity on living things?
2. How do some organisms manage to avoid the impact of gravity?
3. How are dandelions seeds carried by the wind?
4. How do milkweed, cotton grass, willow herb and thistles distribute their seeds?
5. How are pollen grains distributed?
6. How are fungal spores distributed? How many are shed at one time?
7. How do tiny spiders use the wind?
Locator: Venezuela 8. Describe the seeds of the tall trees. How do the seeds of the tall trees exploit the wind and glide to new locations?
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9. Describe the flying frog of Central America.
10. Describe the flying gecko (a type of lizard) of Southeast Asia. How is it different from the other flying lizard of Southeast Asia?
11. Describe the flying squirrel. In horizontal flight, how is lift generated?
======================================================================= ADDITIONAL INFO. Lift occurs whenever there is a difference between air pressure on two sides of a wing. The air pressure above the wing is slightly lower than the air pressure beneath the wing, which is higher. As a result, the air pressure pushes upward on the wing, and the animal rises in the air. This is the force called lift. ======================================================================= 12. What are the limitations of gliding?
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13. What is the most demanding portion of powered flight?
======================================================================== ADDITIONAL INFO. "True powered flight" means that muscles are used to generate lift. Larger animals, as a general rule, can only fly using muscle power. Powered flight is very energy-intensive. As a result, anything that flies must eat a lot of food to sustain it. Birds, for example, eat a lot of food, despite that old misused cliche about "having the appetite of a bird." Also, weight becomes a problem, since larger animals are going to have a harder time powering themselves off the ground. Birds, for example, have bodies especially designed to weigh less. Bird bones are hollow. Their large intestine is tiny, so they cannot store wastes. Birds have replaced heavy jaws and teeth with light-weight beaks. Why? Heavy birds can't get off the ground! ======================================================================== 14. How do insects solve the problems of takeoff?
15. How do birds solve the problems of takeoff? What additional problems face very large birds when they try to take off?
16. What activities are accomplished in the air by damselflies?
17. How do hawkmoths lay their eggs? What do they eat and how?
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18. The tiny bee hummingbird must beat its wings ________ times per second in order to remain stationary. What does it eat?
19. How can birds use their feathers to change the shape of the wings and facilitate flying?
20. Describe the way that kestrels hover.
21. How does the albatross get lift?
22. Where does an albatross fly in order to go against the wind? Why?
23. When are albatrosses not in the air? How big are their wings? What is the shape of their wing?
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24. How do albatrosses take off? How does a flying albatross slow down?
Locator: Coast of Peru Species mentioned in this section: condor 25. How are thermals created by cliffs that lie along the coast?
26. Which bird is the heaviest of all flying birds? How do they manage to stay in the air for hours without effort?
27. What other climatic condition generates thermal currents?
Locator: Serengeti Plains of Africa 28. What parts of the plains generate heat thermals?
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29. Why are vultures dependent upon thermals? How do the thermals regulate the activity of the vultures?
30. How do vultures locate carcasses?
Locator: African mountains 31. Describe the African vulture, the lammergeier, and its diet. How do the birds open the bones?
32. What are the white collared ravens learning from the lammergeier?
33. How does the pied kingfisher find food?
34. Describe the diving technique of the terns and gannets.
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35. Describe the flying techniques of the peregrine falcon. What is its maximum speed during a dive?
36. Describe the flying techniques of the owls. What is unusual about the flight feathers of the owls? What is the shape of the wing? How do owls locate prey?
37. How do bats navigate?
====================================================================== ADDITIONAL INFO: Bats use sonar because they are nocturnal, not because they are blind. Sonar is used to catch insects at night when there is less competition from insectivorous birds for the same food. Some bats do not use sonar, such as fruit bats. All bats have excellent vision, even bats that regularly use sonar to hunt. ======================================================================
38. How many birds have also developed sonar navigation?
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Locator: Cave in Venezuela 39. Describe the oil-birds. How does their sonar differ from the sonar of bats? What do they eat? How do they locate their source of food?
======================================================================= ADDITIONAL INFO: The other bird with sonar is the swiftlet of Southeast Asia. It also lives in caves and uses clicks as its source of sonar. Its clicks are higher than those of the oilbird, so it can detect smaller objects. Attenborough shows cave swiftlets in his new series, Planet Earth, in the Caves episode. You can watch the entire Caves episode on Youtube. ======================================================================= Locator: Skies Above Panama 40. Why do hawks and turkey vultures migrate?
41. How do the hawks and turkey vultures use the thermals in their migration? What do they use as food during their migration?
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Locator: Atlantic Coast of United States 42. How do the phalaropes and sandpipers prepare for their migration? Why are they not able to feed along the way?
Locator: Scandinavia 43. Why do many of the migratory birds cross the narrow straits between southern Sweden and Denmark?
44. Where do small birds fly while crossing the straits? Where do buzzards fly while crossing the straits? Why?
45. Describe the migratory patterns of the red-breasted geese.
46. What other group of animals makes long transcontinental migratory flights?
Locator: South America 47. Describe the migratory patterns of the monarch butterfly.
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48. Describe the migratory routes that run through the Americas. Compare these migratory routes to the migratory routes of Europe-to-Africa and Asia-to-Africa.
49. How thick is the Earth's atmosphere?
50. How is the aurora borealis formed?
51. What causes the colored sunsets and sunrises?
52. What causes rainbows?
53. As the altitude increases, what happens to the atmospheric gases? What happens to the temperature? What happens to the air pressure?
Locator: 8000 feet 54. What living organisms have been found in the atmosphere at altitudes of 4 miles?
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55. How do organisms, such as spiders and winged aphids, manage to survive the extreme cold at very high altitudes?
56. How are clouds formed? Where do the water droplets in the clouds come from?
57. How are hurricanes formed?
58. How are storms formed?
59. How is hail formed? What is the difference between black ice and white ice in a hailstone?
60. How are tornadoes formed? How wide is the vortex of the tornado?
61. What is unusual about the type of water that falls as rain?
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LIVING PLANET EPISODE EIGHT MATERIAL FOR YOU TO COVER Read the CONCEPTS section in the study guide for episode 8. Answer the Concepts Study Questions. Watch Video Episode 8 – Sweet Fresh Water Answer the Video Study Questions.
EPISODE 8 LEARNING OBJECTIVES To become acquainted with: 1. Fresh water 2. Ecology of rivers 3. Changes that occur in a river from beginning to end: currents, nutrients, sedimentation, temperature, oxygen, plant life, animal life 4. The two breeding strategies of fishes 5. The concept of surface tension and how animals exploit surface tension 6. The changes that occur in the Amazon River 7. Types of lakes 8. Zonation in lakes 9. Succession in a lake 10. Ecology of Lake Baikal 11. Ecology of deltas
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CONCEPTS FOR EPISODE 8: SWEET FRESH WATER CHARACTERISTICS OF FRESHWATER HABITATS Temperature The temperature of a body of fresh water depends on (1) the climate of the region in which it is found, (2) the amount of sunshine it receives, and (3) the volume of water. Because of its molecular structure, water tends to resist warming and cooling. The larger the volume of water, the more slowly it changes temperature. Shallow bodies of water normally have less volume than deeper bodies. As a result, they warm up and cool down more quickly. Also, sunshine can reach more of the water in a shallow lake or stream than it can in a deep lake or river. The more water that is exposed to the sunlight, the warmer the water will become. Here is a problem for you to solve: You are monitoring the water quality in the Austin area. You measure the temperature of Bull Creek and Town Lake in August. Which body of water will have the higher temperature? Oxygen The amount of oxygen in a body of water is also important. Most aquatic animals require relatively high levels of oxygen to survive. The amount of oxygen in the water is determined by three things: (1) the absorption of oxygen from the air through the surface of the water, (2) the amount of oxygen formed by photosynthesis of aquatic plants and algae, and (3) the temperature of the water. The absorption of oxygen from the air can be enhanced by the flow rate of a stream or river. For instance, waterfalls and rapids mix in additional oxygen, so that the water downstream has a higher oxygen level than the water upstream. (This is similar to whipping cream - you are adding air to the cream.) Photosynthetic aquatic plants and algae produce oxygen during the day, when the sunlight necessary for photosynthesis is available. At night, the plants and algae do not produce oxygen. Instead, they use oxygen, just like animals do, to produce energy to run the biochemical reactions of their bodies. Thus, the oxygen level in a body of water that contains many plants or algae tends to vary during a twenty-four hour period. The oxygen levels will reach a maximum during the daytime, and drop at night as both the photosynthesizers and the animals consume oxygen. The temperature of the water determines the amount of oxygen that can dissolve in the water. As the temperature increases, the amount of oxygen dissolved in the water decreases. You have probably seen fish in August at the surface of the water, trying to gulp air. That is because the water temperature is high and there is less dissolved oxygen.
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Now, let's return to Bull Creek and Town Lake in August. If you said that Bull Creek should have a higher temperature than Town Lake, you are correct. Bull Creek is shallower than Town Lake, so it contains a smaller volume of water and sunlight can reach all of the water, warming it considerably. Now figure out which body of water will have the highest oxygen level. Nutrient Levels Another important aspect of freshwater habitats is the level of plant and algal nutrients. The most important plant nutrients in fresh water are nitrogen and phosphorus which are released by the decomposition of organic matter. When nutrients are abundant in the water, the plant and algae populations grow rapidly and become very abundant, and the water is said to be eutrophic. When nutrients are scarce, the numbers of plants and algae are low, and the water is said to be oligotrophic. Many bodies of water are naturally eutrophic, such as a lake that receives nutrient-rich water from streams that travel through forests (a rich source for organic material). Sometimes, (too often, actually) human activities raise the nutrient levels of a lake or river. The nutrients may come from fertilizers from lawns, parks and golf courses. Or they may be released by decomposition of organic materials, such as sewage (raw or treated), erosion of rich soils, drainage from cattle feedlots, or dead animals dumped into the body of water by people who are too lazy to dispose of them properly. The process of nutrient enrichment by human activities is called cultural eutrophication. An algal bloom occurs when algae become very abundant in a body of water. The water will look green and be very cloudy. When there is an algal bloom, oxygen levels in the water during the day are very high. But at night, the algae consume a lot of oxygen. They may consume so much that the oxygen is completely used up. Then the animals that live in the water cannot obtain oxygen and die. Also, some algae make toxic compounds, and if they become too abundant, the toxins can kill fishes and other animals directly. Algal blooms often occur during cultural eutrophication. Now let's return to Bull Creek and Town Lake in Austin. If you said that the oxygen levels will be higher in Town Lake, you are correct, if we are considering only the effects of temperature on oxygen levels. As we determined before, the temperature should be higher in Bull Creek because it is shallower, and because warm water holds less oxygen than cool water, you might have said the oxygen should be lower. However, this is really a pretty tricky question. Temperature isn't the only thing to consider here. What if the water in Bull Creek is flowing rapidly over a surface, causing waves and ripples in the water? Will the oxygen level be higher or lower than in Town Lake? And what if there is an algal bloom in Town Lake? What will that do to the oxygen levels during the day? During the night?
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RUNNING WATER: STREAMS AND RIVERS A river may begin in the mountains, as rain falls on the high peaks and begins to flow toward the sea. At its source, the land is steep and the river, really a small stream at this stage, flows swiftly over and around rocks and boulders. The water is cold and flows rapidly, so the oxygen levels are high. Nutrient levels are low because (1) the plant communities of alpine regions do not make much organic matter to give to the river, and (2) the river has not gathered water yet from other streams and rivers, which would add to its own organic material. The force of the water is so strong that rocks and boulders can be moved as easily as if you were moving a pillow. As the rocks and boulders roll along, they grind away at the rock bottom, wearing away deep grooves called gorges and canyons. The process of wearing away rocks and soil and carrying the small particles away is called erosion. As the water flows toward the sea, more and more streams and rivers add their loads of water, nutrients and suspended soil and rock particles to the main river. The river grows larger and larger, and more nutrient rich. The amount of soil and rock particles brought down from the mountains becomes so large that the river begins to get cloudy. By the time it reaches the sea, the water will be the color of hot chocolate. As the river reaches the lowlands, the climate becomes warmer, and the temperature of the river water begins to rise. The land begins to level off and the river slows down. As the river slows, it begins to drop its rocks and soil particles. At first only the heaviest particles drop out of the water. The very smallest particles of mud and clay remain suspended in the water. The nutrients in the river water support large populations of algae which give the river water a green color. Aquatic plants such as cat tails and rushes become established along the shore, now that the river has slowed enough that they will not get swept away. When the river gets close to the sea, the land becomes level. The river, which is very large now, is also very slow. It winds back and forth across the level plain, seeking the path of least resistance. As water flows around a bend, the water on the outside of the bend moves faster and wears away the river bank. The water on the inside of the bend slows down and drops some of the sand and mud it is carrying, forming shoals. By this process, the river travels across its flood plain, carving away at the rich soil on the one hand, and adding nutrient rich soil from upstream on the other. Very near where the river releases its water into the sea, the land is so level that the river finally begins to drop the smallest particles of mud. Vast deposits of mud are created as the river literally builds land out into the sea. The area of land created by the river is called a delta. In places where humans haven't built their own homes, the deltas are covered with marshes, vast areas of rushes and grasses where millions of birds and other animals nest and raise their young.
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STILL WATER: LAKES AND PONDS There are at least four different kinds of lakes, based on how they were formed. These include: 1. Lakes formed by geological faults. When large sections of the earth's surface are fractured and broken apart, deep depressions are often formed. These collect water to form lakes. Examples of lakes formed in this fashion include Lake Baikal (Russia), Lake Tanganyika (East Africa), Pyramid Lake (Nevada) and Lake Tahoe (California). 2. Lakes formed by damming rivers. Rivers can be dammed by volcanic activity, landslides, natural log jams (such as the one that formed Caddo Lake, the only natural permanent lake in Texas), and of course, people. The depth of a lake formed in this way depends on the landforms surrounding the river. If the river is flowing through a deep gorge, the lake that forms may be very deep. If the river is flowing through low hills, the lake will be shallower. Lakes formed in this way tend to have an irregular outline, as water is backed up into the river's tributaries. For a good example of this type of lake, look at a map of Lake Travis. 3. Lakes formed by glaciers. Glaciers are large bodies of ice that move slowly down slopes under their own weight. As a glacier moves along, it grinds away at the rock surface underneath. After it melts, depressions remain that collect rain water to form lakes. The Great Lakes of North America are an example of very large lakes formed by glaciers during the last Ice Age about 10,000 to 20,000 years ago. 4. Lakes formed by meandering rivers. As a large river wanders around on its flood plain, the bends in the river change shape. Once in a while, the bend comes back around very close to the upstream section. During a flood, the river carves a new course, taking the shortest route, and the bend in the river is cut off from the rest of the river, forming a shallow lake. This is shown in the videotape.
AQUATIC LIFESTYLES: PLANKTON, NEKTON AND BENTHOS Plankton are organisms that float or are weak swimmers. They go where the water currents take them. Plankton are usually divided into two broad categories: phytoplankton (producers) and zooplankton (consumers). The plankton are the basis of open water food webs. Nekton are organisms that are strong swimmers. They go where they want, regardless of the currents. In freshwater systems, fishes are the main type of nekton. Nekton are consumers. Benthos are organisms that live on or in the bottom. The bottom is called the benthic region and may be mud, sand, gravel, rocks, etc. Typical benthic animals are worms, insect young and crustaceans (such as crayfish). Other benthic organisms include bacteria, algae and protozoans. Benthic food webs include grazers, predators, © Speer, Maxim and Strong
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scavengers and decomposers. If algae are present, they are the base of the food web. This occurs when sunlight reaches the bottom. If the bottom is dark and will not support producers, then the food webs are dependent on decomposers. The decomposers (bacteria and fungi) must rely upon material that falls onto the bottom.
LAKE ZONATION Lakes, especially deep ones, contain many different types of habitats for organisms. Along the shore of the lake, where the water is so shallow that light can hit the bottom, there is a zone of aquatic plants rooted in the mud on the bottom. This zone is called the littoral zone. There are lots of food and hiding places for fishes and other animals in this zone. The littoral zone has an open water region and a benthic region. The littoral benthic region is rich with organic matter, nutrients and life forms. In deeper water where the sun does not strike the bottom, the zone of open water lit by the sun is called the limnetic zone. It is occupied by floating algae and cyanobacteria (the phytoplankton) and many protozoans and small animals that feed on them (the zooplankton). The zooplankton are in turn eaten by fishes (the nekton) and other large animals (such as diving ducks and otters). In the deep parts of a very deep lake, it is always dark. All the light is absorbed by the water before it gets down to the deep parts. This dark zone is called the profundal zone. Unlike the littoral and limnetic zones, where photosynthesis is the ultimate source of food, the organisms that live in the profundal zone depend on dead and dying organisms that settle out of the limnetic zone for food. Bacteria and fungi decompose the dead organisms, and protozoans and small animals eat the bacteria and fungi. Some animals are scavengers and eat the dead organisms themselves. The profundal zone has an open water region and a benthic region. Virtually all trophic activity occurs in the benthic region of the profundal zone. The profundal benthic region is quite variable depending on the lake. It usually has fewer life forms than the littoral benthic region because there are fewer nutrients and no light. In very deep lakes, the profundal benthic region can be anoxic (without oxygen).
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This is a simple diagram of lake zonation.
SUCCESSION: THE LIFE OF A POND Lakes and ponds are not permanent. In a sense, they have a lifespan just like animals, with birth, youth, middle age, old age, and death. Bodies of water undergo succession, as do terrestrial ecosystems. (Remember Unit 1?) Let's follow the "life" of a beaver pond as an example. Birth: The pond is born when a family of beavers dam a stream. Water pools behind the dam. At first there is little life in the pond. The bottom of the pond lacks organic material to provide nutrients for plant growth. It takes a while for the algae that make up the phytoplankton to colonize the new pond. Youth: As the stream continues to bring organic material into the pond, organic material begins to build up. Now enough nutrients are available for rooted aquatic plants to move into the littoral zone. Middle Age: As the phytoplankton and aquatic plants die and fall to the bottom, more and more organic matter builds up in the pond, which provides more and more nutrients for more and more plants. The littoral zone begins to move farther and farther into the center of the pond. Old Age: The stream brings in soil and rock particles as well as organic material. The combination of dead organic matter produced within the pond and the sediments brought in by the stream begin to fill in the pond. As the profundal zone fills in, the bottom eventually is close enough to the surface to be exposed to the light. Now the aquatic plants can cover the bottom of the whole lake, forming a marsh. © Speer, Maxim and Strong
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Death: Dead plant materials and sediments continue to build up, until the lake fills in entirely and a beaver meadow is formed.
BREEDING STRATEGIES OF FISHES Like all other organisms, fishes must reproduce. The main goal of an organism in reproducing is to maximize the number of fertile offspring it has over its lifetime. There are a number of different strategies that fishes use to achieve this goal. One strategy an organism may use is to feed and grow for most of its life, then use all of its stored energy to produce a large number of offspring at once, and then die. An example of a fish that uses this strategy is the Pacific salmon. A Pacific salmon hatches from an egg laid in a cool freshwater stream. The young fish feeds and grows among the rocks and gravel of the stream. When it is large enough, it begins to make its way to the ocean. After it reaches the sea, it continues to feed and grow in size for a number of years. Eventually, it reaches maturity. The fish, now very large, begins a journey that will take it back to the stream in which it hatched. As a young fish, it had memorized the smell of its birthplace. Now, the salmon uses its sensitive sense of smell to find the right stream. As it journeys up the rivers and streams to its birthplace, it must fight its way up rapids and waterfalls. When the fish reaches its old home, it mates. If it is a male, it must fight with other males for the females. If it is a female, it lays thousands of eggs, and then the male spreads sperm over the eggs. The journey and the mating process are so difficult that the males and females are exhausted at the end. They die soon after mating, and their dead bodies provide nutrients that will nourish the algae and other organisms that their young will eat. The young must be able to survive on their own with no help from their parents. Most of the eggs and young fish don't survive; they are eaten by various predators, or starve to death. But enough eggs hatch and enough young grow that a few of the male and female's offspring make it back to the ocean again, and return themselves to the stream to take their turn at mating. Another strategy an organism can use is to have fewer offspring at one time, and to invest the energy it could have used to make more offspring in taking good care of the few it did have. In the videotape, you will see a couple of fishes called sticklebacks being eaten by various predators. During the breeding season, a male stickleback changes from silver all over to having a bright red throat and breast and a bright bluegreen back. This color pattern indicates that he is ready to breed. He finds a suitable place to build a nest and defends it against other males. The nest is built by digging a depression in the sand and covers it with a tent made of pieces of plants he glues together with a sticky substance. After he finishes building the nest, he begins to court females. When he sees a female with a swollen belly indicating that she is ready to lay eggs, he starts to zig and © Speer, Maxim and Strong
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zag through the water. She responds to his dance by swimming toward the male. He turns around and leads her to the nest. She enters the nest and lays her eggs and he spreads sperm over them. When all the eggs have been laid, the male drives away the female and any other females and males that approach the nest, protecting the eggs from being eaten. He fans the nest with his fins to make sure the developing eggs have enough oxygen. After 6-10 days, the eggs hatch. The young stay in the nest until they have used up their yolk supply. After a few days, groups of young begin to venture out of the nest, but they are still too small to defend themselves. Dad picks them up in his mouth and spits them back into the nest. He continues to do this until the young are big enough to take care of themselves. While you watch the episode, look for the discus fish, another species that takes care of its young. How does the discus fish differ from the stickleback in parental care?
================================================================== EVOLUTIONARY ASPECT: Scientists have tried to classify these breeding strategies into two main categories: r strategy and K strategy. [We are not going to discuss where the r and K comes from. If you are interested, check out an ecology book.] r strategy: the plan is to have many, many offspring and invest as little energy as possible into each. Most of the offspring will die; however, there are so many of them that at least a few will survive. The ones that survive carry your genes into the next generation. K strategy: the plan is to have very few offspring and invest as much energy as possible into each. Each offspring has a very good chance of survival because the parents spend a lot of time and energy providing food, protection, care, etc. for the offspring. However, because the parents spend some much time and energy on each offspring, they cannot afford to have very many. The ones that survive carry their genes into the next generation. Obviously, both strategies work for different organisms, including both plants and animals. Bluebonnets are a good example of a plant with r strategy. The coco-de-mer palm tree (see Episode 10) is an example of a plant with K strategy. (The nut is kept on the parent tree for seven years until it is mature; the parent tree provides the nut with time, food and energy -- parental "care" for its offspring.) You should also have gotten the message by now that nature does not pay any attention to categories created by hopeful scientists. There are many different breeding strategies that do not nicely fit into either of these two categories. ==================================================================
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CONCEPTS STUDY QUESTIONS FOR EPISODE 8 1. Describe how factors such as geographical location, sunshine, and volume affect water temperature.
2. Describe how turbidity, photosynthesis and temperature affect the amount of oxygen dissolved in the water.
3. Describe how decomposition and runoff affect water nutrient (nitrogen and phosphorus) levels.
4. Compare eutrophic and oligotrophic bodies of water with respect to nutrient level, oxygen level, algae level, and turbidity (cloudiness).
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5. Describe changes that occur in a river as it flows from the mountains to the sea, especially speed of current, nutrient level, temperature, oxygen level, erosion, suspended silt, and turbidity.
6. Describe what happens at the inner and outer banks at the curve of a meandering river.
7. List and compare the four processes by which lakes are formed.
8. Describe and compare phytoplankton, zooplankton, nekton and benthos.
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9. Describe and compare the three main zones of a pond or lake.
10. Describe the process of succession in a beaver pond from "birth" to "death".
11. Describe and compare the two main breeding strategies (r and K) used by fish (and other organisms).
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VIDEO STUDY QUESTIONS FOR EPISODE 8 Locator: Venezuela 1. What are the effects of rainwater on mountains?
2. What is extraordinary about water? How much of the water on this planet is salty? How much is fresh water? How is the fresh water formed?
3. Describe the rivers that pass through the Andes on their way to the Amazon River. What are the problems that face organisms that live in these waters?
4. Describe the torrent ducks. What body adaptations allow them to live in these waters?
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5. Describe torrent moss. What organisms live in the moss?
6. How do the caddisfly larvae live in these waters? What other strategies are used by insect larvae to keep them from being swept away by currents?
7. Describe the black fly larva. What is its strategy?
8. What other strategy is used by caddisfly larvae?
9. Describe the dipper. Where are these birds found? How do they propel themselves under water?
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Locator: North America 10. Describe the hellbender. How does it avoid the currents? What does it eat? (For more info, see http://www.hellbenders.org/ )
Locator: Malaysia 11. How does the big headed turtle move through the waterfalls?
Locator: West African waterfalls 12. Describe the hairy frog. What is unusual about this amphibian? How does it keep its grip on the rocks?
============================================================================= CLARIFICATION: These are not true claws like reptiles have but are really "pointy" toes. =============================================================================
Locator: Amazon 13. What is carried by brown water? How do the waters manage to erode mountains?
Locator: China 14. What is unusual about the Yellow River? How many pounds of soil and mud are carried in a cubic yard?
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15. When a young vigorous river encounters hard rock, what happens?
Locator: Iguazu Falls 16. How are the falls moving upriver?
17. Why do swifts perch behind the waterfalls?
18. As the rivers leave the mountains, what happens to the shape of the river? How does this change the character of the river?
19. How many different species of fish are found in the Amazon? How large does the arapima grow?
20. How have the fish evolved to suit the various conditions of the water? Use the catfish family to describe some of the varieties that have evolved to suit the various conditions.
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21. How does the Discus protect its young fry?
22. What two kinds of electric charges are produced by the electric eel? What is each used for?
23. Describe the splashing tetras. How do they protect their eggs from the many predators?
24. Describe the piranha.
25. As the river gets older, it begins to loop and meander. What causes these loops? How are isolated lakes formed?
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26. Describe the great Amazon lily. How do they avoid competition from other water plants? How fast can they grow?
27. Describe the flower of the giant Amazon lily. How are they pollinated?
28. Describe the jacana. What does it eat?
29. What is surface tension? How does it form?
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30. Many organisms take advantage of surface tension. Describe the particular adaptations of the following: Animal described in Episode 8
Pond skater
Whirligig beetle
Larvae of the great diving beetle
Water boatman
Camphor beetle
European fishing spiders
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31. How do the lakes and ponds that are formed by geological faults differ from the lakes and ponds that are fed by streams or created from cut-off rivers?
32. What happens to the sediments carried by a river when the river enters a lake? What conditions change for the animal life?
33. Where is the most fertile part of the lake? Why are they so fertile?
34. What problem faces organisms that try to live on the bottom of a lake?
35. Why do new species evolve in isolated lakes?
Locator: Russia 36. Describe Lake Baikal. How many unique organisms are found in this lake only? Why?
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Locator: Amazon 38. What happens when the Rio Negro meets the Amazon?
39. Describe the capybara. What do they eat?
40. Describe the Amazonian otters.
Locator: India 41. Describe the gavial. What does it eat? How is it adapted for its diet?
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42. Describe the hooded merganser. What does it eat? How is it adapted for its lifestyle?
43. What other animals use fish as food?
Locator: Africa. 44. What body adaptations are found in the fishing owl of Africa?
Locator: Amazon, last phase of life 45. Describe the floods that occur yearly.
46. How are the trees adapted for these flooded conditions?
47. What does the matamata turtle eat?
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49. Where is sand deposited? What type of plants grow thickly on the banks?
50. Describe the bittern.
51. How are river deltas formed? Why are they fertile?
Locator: Twin deltas of Tigris and Euphrates in Iraq 52. Describe the lifestyle of the Marsh Arabs.
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53. The deltas are very rich in nutrients. Where are the following delta birds found? Bird
Location
Snow geese
Magpie geese
Brolga cranes
Scarlet ibis
Stilts and plovers
Flamingos
Spoonbills
Distributed over most of the world
54. Describe the Amazon delta. How much of the world's river water is contained in the Amazon alone? How wide is the mouth of the Amazon? How far into the ocean does the fresh water of the Amazon retain its identity?
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LIVING PLANET EPISODE NINE MATERIAL FOR YOU TO COVER Read the CONCEPTS section in the study guide for episode 9. Answer the Concepts Study Questions. Watch Video Episode 9 – Margins of the Land. Answer the Video Study Questions.
EPISODE 9 LEARNING OBJECTIVES To become acquainted with: 1. Tides 2. Seaweeds: different types and characteristics 3. Ecology of estuaries: location, characteristics, life forms and adaptations 4. Ecology of mud flats: formation, location, characteristics, life forms and adaptations 5. Ecology of mangrove flats: location, characteristics, life forms and adaptations 6. Ecology of intertidal zone: location, characteristics, life forms and adaptations 7. Inhabitants of seaside cliffs 8. Ecology of sandy beaches: location, characteristics, life forms & adaptations
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CONCEPTS FOR EPISODE 9 - MARGINS OF THE LAND TIDES Tides are the periodic rise and fall of the water level of the ocean due to the gravitational pull of the moon and sun on the water. The ocean bulges on the sides of the earth that are in a straight line with the sun and moon, and hollows out on the sides perpendicular to the sun and moon. The bulges and hollows cause the tides as the earth rotates. The moon pulls harder on the water than the sun because it is closer to the earth. The highest tides occur when the earth, moon and sun are arranged in a straight line: EARTH - MOON - SUN
or
SUN - EARTH - MOON
At that time, the pull of the moon and sun add up to a very strong yank on the water. The lowest tides occur when the moon and sun are at right angles to each other: MOON
| SUN - EARTH
In this position, the pulls from the moon and sun conflict (each pulls in a different direction) and the sum is a weak pull on the water. There’s a great website to help you understand these concepts at: http://oceanlink.island.net/oinfo/tides/tides.html
SEAWEEDS: MARINE ALGAE Seaweeds are large marine algae that grow attached to solid objects such as rocks in the intertidal zone. Their bodies are divided up into three regions: (1) the blade, a broad flat surface that resembles the leaf of a land plant; (2) the holdfast, a branching rootlike structure with which the seaweed holds on to the solid surface of the bottom; and (3) the stipe, a more or less narrow region that connects the blade with the holdfast. The largest seaweeds, the kelps and their relatives, often have swollen gas-filled blisters or balloons, called air bladders, along the blade and/or stalk. The air bladders act as floats, keeping the blades at the surface of the water when the tide comes in so that they can use the abundant light at the surface for photosynthesis. © Speer, Maxim and Strong
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There are three main groups of seaweeds. They can be told apart by their colors. The color differences are caused by differences in the light-absorbing pigments involved in photosynthesis. (1) The red algae are mostly small seaweeds, often lacy in appearance, and most common in warm tropical waters (although some species do occur in cold waters). Their red pigments are adapted for absorbing the weak blue light found at some depth in the water, so the red algae are often the deepest-occurring seaweeds in places where all three types are found. (2) The green algae are also mostly small seaweeds that occur in ocean waters all over the planet. They vary widely in appearance. This group also includes a lot of microscopic algae, most of which occur in fresh water. The green algae are considered to be the ancestors of plants. (3) The brown algae includes the largest seaweeds of all: the giant kelps that occur in the Pacific Ocean off the west coast of North America. These seaweeds can reach lengths greater than 100 m. Other kinds of kelps and rockweeds, all brown algae, are very common in cool ocean waters the world over. Look for the sea palm in the episode. Seaweeds provide an important food source for intertidal organisms on rocky shores. Herbivores like sea urchins and snails graze on the seaweeds, and they are in turn food for predators like starfish and sea otters. In addition, where seaweeds such as the giant kelps are common, they provide hiding places for the vulnerable young of crustaceans and fishes. These young animals hide and feed among the kelp, only leaving when they are large enough to defend themselves. These areas are often called nurseries. Many commercially important species of fish and shellfish depend on these nurseries to ensure the survival of their young. When the nurseries disappear or are damaged, due perhaps to pollution, the fish and shellfish numbers decrease, endangering the livelihood of fishermen and driving up seafood prices. (You'll see the giant kelps in Tape 11.) Seaweed Web Site:
http://www.seaweed.ie/
ROCKY INTERTIDAL ZONES There are several technical terms that can be used to describe the different zones of a rocky intertidal shore. We are going to use the same terms that Attenborough uses in the video. If you check out web sites about rocky intertidal zones, be aware that their terminology might be different. The low intertidal zone is the region that is usually underwater. it is only exposed at the lowest low tides. The organisms that live here must be able to swim © Speer, Maxim and Strong
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down into deeper water or withstand an hour or two of exposure when the tides are unusually low. Some of the organisms that live in the low intertidal zone include sea stars, sea anemones, sea cucumbers, sponges, sea squirts, seaweeds, and fish. The middle intertidal zone is exposed to the air for a number of hours during every low tide. During high tide, this area is usually completely underwater. The organisms that live here must be able to survive daily exposure for several hours. They also need to hang on tightly to the rocks, because there is a lot of wave action. Some organisms that live in the middle intertidal zone include limpets (a type of snail), periwinkles (another type of snail), mussels, gooseneck barnacles and sea palms. The high intertidal zone is exposed to the air for long periods of time every day. This area can get very hot or very cold, depending on the environmental temperature. During high tide, this area is alternately covered and uncovered by the waves. The organisms that live here must be able to survive extreme temperature changes and long periods of exposure to air. Barnacles are the main types of organisms that live in the high intertidal zone. Watch the video carefully to see the three zones and the organisms that live in each.
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CONCEPTS STUDY QUESTIONS FOR EPISODE 9: 1. Explain what causes tides.
2. Describe the body of a typical seaweed (marine algae).
3. Compare the three groups of seaweeds (marine algae).
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VIDEO STUDY QUESTIONS FOR EPISODE 9: 1. What forces are responsible for the tides?
Locator: Bay of Fundy Species mentioned in this section: axis deer, Indian golden-banded woodpecker, wild boar, terns, kingfishers, great white heron 2. How high are the tides in the Bay of Fundy?
3. Is the boundary between sea and land permanent? Explain your answer.
4. Describe an estuary. What problems face the inhabitants of an estuary? What are the benefits of living in an estuary?
======================================================================== ADDITIONAL INFO: Estuaries are found at the mouths of rivers where they meet the sea. The water in estuaries is brackish (saltier than fresh water, but not as salty as sea water). Estuaries are under the influence of the tides. When the tide comes in, sea water moves up the river, making the water saltier. When the tide goes out, fresh water from the river makes the water less salty. Thus, estuaries experience daily swings in the saltiness of the water. Most organisms find it difficult to adjust so quickly to changes in saltiness. Thus, most estuaries are inhabited by the relatively few organisms that are tough enough to handle this challenge. They are rewarded by the vast amount of organic material provided by the rivers, making estuaries some of the richest habitats in the world in terms of growth and reproduction. ======================================================================== © Speer, Maxim and Strong
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5. Fill in this table for these estuarine inhabitants. Include what they eat and other information, such as building tubes or living in the mud. Animal
Lifestyle
mollusk (Scorbicularia)
crustacean (Corophium)
ragworms
spire shell
peacock worm
cockles and mussels
6. How do the mussels cope with the tides?
7. Describe the oystercatcher. What three different techniques for opening mussels are used by oystercatchers? How does one learn its technique?
8. How many spire shells are found per square yard in the estuary mud?
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9. Describe the following wading birds and their feeding behavior: Wading Bird
Feeding Behavior
godwit
curlew
dunlin
ringed plover
avocet
10. In one year, what is the amount of (mussel) flesh eaten by one oystercatcher? What does this indicate about the fertility of the estuaries?
11. How do plants get a hold in the estuary flats? How do glassworts promote the buildup of land?
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12. What plant is the mud colonizer of the tropics?
13. Describe the tidal mangrove flats.
14. What animals are found here?
15. Describe the proboscis monkey. Where are they found? Why are they restricted in their distribution?
16. Describe the mangroves. How many species of mangroves are found throughout the world?
17. How are their flowers pollinated?
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18. Describe the seed of the mangrove. Where does it germinate and begin to grow? How is it suited for establishing a new plant?
19. Describe the characteristics of the mangrove mud.
20. Why are the roots of the mangrove shallow? How do these shallow roots support the trees?
21. Explain how the mangrove roots gather nutrients.
22. How do the mangroves gather water? How do they deal with the problem of salt?
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23. How do mangroves solve the problem of acquiring oxygen?
24. How do the mollusks deal with the problem of low tide? Why?
25. Describe the three types of mudskippers found in the mangrove flats. What do they eat?
26. How does the largest species advertise for a mate?
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27. How do some terrestrial crabs manage to get oxygen?
28. Describe the soldier crabs. What do they eat?
29. Describe the mangrove crab. How does it keep moist? What does it eat?
30. Describe the fiddler crab. What is the large pincer of the male fiddler crab used for?
31. What birds are found in the mangrove flats at low tide? What do they eat?
32. What problems arise at high tide?
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33. How do the following animals deal with the problems of high tide? a. African mangrove snail
b. soldier crab
c. mudskipper
34. Describe the archerfish.
35. Describe the otters. What do they eat? Where are they found?
36. Describe the estuarine crocodile. Why is it so widely distributed?
37. How are dry forests produced from the mud flats? How do banks of mud and sand protect the land from waves?
38. Are tall waves associated with shallow water or deep water?
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39. How big is the intertidal zone in areas where the land drops sharply off into the sea?
40. What are the two problems that intertidal communities have to cope with?
Locator: northwest coasts, North America Species mentioned in this section: sea urchin, giant sea anemones, sea squirts, starfish, mussels, winkles, gooseneck barnacles 41. Describe the organisms that live on the bottom band of the tidal community. When is this lower band exposed? What happens to these animals during the low tides?
42. What determines the lower limit of the band of mussels?
43. Why are mussels found in dense bands in the middle intertidal zone? What other animals are found here? How do mussels attach themselves to the rock?
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44. What animal replaces the mussel in more exposed areas? How do they attach to the rocks? How do they feed?
45. Describe the sea palms. How do these plants actively remove the mussels from the bare rock?
46. What determines the upper limit of the band of mussels?
47. What animal dominates the highest intertidal band? How do barnacles survive at the high tide band?
48. What three factors determine which organisms will dominate in each band of the rocky intertidal zone?
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Locator: southernmost tip of Australia Species mentioned in this section: mollusk larva, hydra, nematode worm 49. What is the effect of the waves on the sandstone cliffs of Australia? What happens to the debris?
50. What are the problems of living on a sandy shore?
51. How do sand grains retain moisture? What tiny organisms live in the sand grains?
52. Describe the sandmason worm (larvae and adult).
53. Describe the sand hoppers. What do they eat? How do they protect themselves from drying out?
54. How many sand hoppers can be found in one square yard of beach sand?
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55. Describe the ghost crabs. What do they eat?
Locator: South African beach 56. Describe the plough snail. How does it locate food? How does it travel? How does it avoid being stranded on the beach?
Locator: Costa Rica 57. Turtles belong to what group of animals? Why do they lay their eggs on the beach?
58. Describe the nesting habits of the Ridley turtle. Why do they lay their eggs within a few days? How many young turtles will survive?
59. Describe the nesting habit of the giant leatherback turtle. What do we know about these turtles? Where are the two nesting sites that we know about? Why is it endangered?
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LIVING PLANET EPISODE TEN MATERIAL FOR YOU TO COVER Read the CONCEPTS section in the study guide for episode 10. Answer the Concepts Study Questions. Watch Video Episode 10 – Worlds Apart Answer the Video Study Questions.
EPISODE 10 LEARNING OBJECTIVES To become acquainted with: 1. Characteristics of islands and different types of islands 2. Island ecology: location, climate, characteristics, life forms and adaptations 3. Coconut palms and seed dispersal 4. Specific islands, their characteristics and inhabitants: • Aldabra • Seychelles • Komodo • Hawaiian Islands • Galapagos • New Zealand 5. The concept of isolation 6. The effects of isolation on island inhabitants 7. Relationship between island inhabitants and humans 8. The concept of extinction 9. The Polynesians and their impacts on islands
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CONCEPTS FOR EPISODE 10 – WORLDS APART ISLAND ECOLOGY Islands, especially remote islands, are often studied as miniature terrestrial ecosystems. A remote oceanic island is a fully functional ecosystem but, due its isolated location, few life forms come to the island or leave it. Also, it is probable that genetic change (evolution) may occur more quickly on these islands, since island populations are smaller than ones on the mainland. A change in the genetic makeup of one plant, for example, may spread more quickly through a population if it is one of 10 plants, as opposed to 100,000 plants. As a general rule, species diversity is richer on large islands than on small islands. There are several possible reasons: (1) large islands may have more different types of habitats than small ones; (2) larger islands may be easier for plants and animals to find as they move from the mainlands (either voluntarily or involuntarily, if they are blown out to sea by a storm); and (3) the larger populations on large islands may have a better chance of surviving, since there will be more resources, more area, more genetic diversity and less chance of being wiped out by accident. As Attenborough talks about the Hawaiian Islands in the episode, look at the multitude of habitats. Also, he discusses how animals, such as the ancestral honeycreeper and ancestral Drosophila, probably reached the islands in the first place. There are often a number of problems that face plants and animals which live on islands, especially remote oceanic islands. One is the availability of fresh water. While some birds, such as sea birds, are able to drink salt water by extracting the salt from it, most animals require fresh water to drink. Most plants also require fresh water. Thus, an island with more-or-less permanent pools of rainwater has a far better chance of sustaining more life forms than an island with no immediate source of fresh water. Another problem is finding food. Plants, if they can get established, can make their own food. If there is abundant plant life, then animals can survive by eating the plants. Many animals, especially birds, can find food by fishing in the surrounding oceans. Food can be a real problem for animals, especially if there are seasonal differences in food availability. A tropical island may have food available year round but this is not always the case on all islands. Think of the small islands in the Great Lakes, which have isolated populations of small deer mice and other animals. Winter conditions are harsh and food is scarce.
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TYPES OF ISLANDS Islands are not all the same. Some are formed from volcanic activity. Others, like New Zealand, formed when a large supercontinent split apart. Others are stabilized sandbars. Still other islands are formed from the activity of corals. Barrier islands form when sandbars become colonized and stabilized by plants. These islands usually form in the shallow waters next to a continent. These barrier islands break up the force of the water and protect the mainland from storms. Usually, a quiet stretch of water lies between the barrier island and the mainland. If you look at a good map of Texas, you will see a chain of barrier islands stretching along the Gulf Coast. Padre Island, Matagorda Island and Mustang Island are good examples of barrier islands. Look between the mainland and Padre Island and locate the Laguna Madre. The Laguna Madre is a valuable nursery for many of the deep sea inhabitants that lay eggs in these waters and leave their young to grow up in this more protected setting. The wave action on rocky coasts (as shown in Episode 9) can separate chunks of the mainland into isolated islands. Mangroves, growing in shallow off-shore waters, can create isolated mangrove islands. These can be found in Florida, along the fringing tip of the Florida Peninsula and around the Keys. The best-known islands built by living organisms are built from the activity of corals. You will see coral reefs discussed in Tape 11. Coral reefs form in shallow, tropical waters, either along the edges of continents or around submerged volcanic islands. The water must be clean and unpolluted. According to Smith (1992), there are three main categories of coral reefs: (1) a fringing reef, which grows from a mainland or island into the sea, (2) a barrier reef which grows along a shoreline and is separated from the mainland by a shallow stretch of water called a lagoon, and (3) a coral atoll which forms when a volcanic island lowers, leaving a horseshoe or ring of coral reefs and islands enclosing a shallow lagoon. The Great Barrier Reef off the eastern coast of Australia is an example of a barrier reef. Many of the islands of Hawaii are surrounded by fringing reefs that grow from the edge of islands out. The island of Aldabra, shown in this episode, is typical of a coral atoll. Volcanic islands are formed from basalt, as seen in Episode 1. References: Amos, William H. 1980. Wildlife of the Islands. Harry N. Abrams, Inc., NY. Jensen, Albert C. 1979. Wildlife of the Oceans. Harry N. Abrams, Inc., NY. Smith, Robert Leo. 1992. Elements of Ecology, 3rd ed. HarperCollins, NY. Thurman, Harold V. Introductory Oceanography, 5th ed., Merrill, Columbus, Ohio.
Web sites for information about New Zealand birds: Kiwi Recovery: http://www.kiwirecovery.org.nz/ Takahe and other flightless New Zealand birds: http://www.terranature.org/flightlessBirds.htm © Speer, Maxim and Strong
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CONCEPTS STUDY QUESTIONS FOR EPISODE 10: 1. Describe the effect of island size and isolation on genetic change (evolution).
2. Explain the effect of island size on the number of species living on the island.
3. Describe the different types of islands, how they are formed, and give examples.
4. Describe how a barrier island is formed and how it protects the mainland.
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VIDEO STUDY QUESTIONS FOR EPISODE 10: 1. What is the impact of islands on the species that inhabit the islands?
Locator: Aldabra, Indian Ocean 2. Describe the island. Where is Aldabra located?
======================================================================= Aldabra Websites: http://worldwildlife.org/ecoregions/at1301 http://www.aldabra.org/ ======================================================================= 3. What types of birds are found on the island?
4. Describe the frigatebirds and their mating behavior.
5. Where do the red-footed boobies nest?
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6. Where do the sooty terns nest? How many sooty terns nest on Aldabra?
7. What does the vast number of animals indicate about the surrounding sea? How much food is available for animals on the island itself?
8. Why do the terns nest on this island?
9. How do plants reach remote islands?
10. Describe the nut of the coconut palm. How is this plant adapted to dispersing its seeds into the sea? How long can the coconut seed survive in salt water?
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11. How did the coconut crab reach Aldabra?
12. Describe the coconut crab. What does it eat?
13. How do most crabs breathe in water? What adaptation allows the crab to breathe in air?
14. How does the coconut crab breed?
15. Describe the giant tortoises of Aldabra. How did their ancestor probably reach the island?
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16. What are the dangers involved in living on Aldabra?
17. How do the tortoises cope with the heat of midday?
18. How do the birds prevent themselves from overheating? How often must tortoises drink fresh water?
19. How many giant tortoises are found on Aldabra? What do they eat?
20. Describe the changes that 50,000 years of evolution have produced in the plants of Aldabra: a. the sedges
b. Lomatophyllum
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21. Describe the coco-de-mer nut.
22. Where are the coco-de-mer palm trees found?
23. Describe the male coco-de-mer tree and the gecko that lives on them.
24. Describe the female tree. How long does it take to produce a nut? (Remember K strategy?)
25. How is the coco-de-mer nut different from a coconut? What is unusual about the seeds of this plant?
26. Why has the coco-de-mer not spread to other islands?
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27. What changes have occurred in the birds that are isolated on Aldabra? Aldabran Bird
Changes
sacred ibis
kestrel
Aldabran sunbird
Aldabran rail
28. Why would an island bird become flightless?
29. Describe the dodo of Mauritius. Why did it become extinct?
30. Why did the giant tortoises of Mauritius and other islands become extinct?
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31. How did the tortoises of Aldabra manage to avoid extinction?
32. How do the tortoises of Aldabra differ from the African tortoise that is closely related?
33. How does a normal African tortoise protect itself? How does this compare to an adult Aldabran tortoise? Why is there a difference?
======================================================================== AUTHORS’ NOTE: Why are the Aldabran tortoises (and other island residents) giants? One possible reason may be due to the very small gene pool on islands, which magnifies any small differences. This magnification often leads to very large changes in the characteristics of the entire population. You would not expect to see this in a large population, just due to the overall size of the gene pool. However, in isolated situations like islands, small genetic changes can lead to large changes in the appearance of the island residents. Also, there is a very good possibility that there is a strong selection pressure in being large. Perhaps it helps the animals with temperature regulation or helps the animal better survive periods when food is scarce. Remember how natural selection works -- if there is an advantage to being very large, then those animals would be more likely to have offspring, which in turn have a better chance of surviving and passing on their genes. =======================================================================
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Locator: Komodo in Indonesia 34. Describe the Komodo dragon. What do they eat?
35. What sense do they rely upon to detect prey?
36. What is the advantage to their large size?
37. What other lizards are they related to?
======================================================================= AUTHORS’ NOTE: Until recently, no one thought the Komodo dragons were poisonous. However, recent work with Komodo dragons has revealed that their bite is indeed venomous. You can find more information at: http://news.nationalgeographic.com/news/2009/05/090518-komodo-dragon-venom.html ======================================================================= © Speer, Maxim and Strong
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Locator: Hawaiian Islands 38. Where are the Hawaiian Islands located? How were they formed?
39. Why are there so many different habitats on these islands?
40. What is the effect of the multitude of habitats on the organisms that live there?
41. Describe the different honeycreepers and their diet: Hawaiian Honeycreeper palila
amakihi
apapane
akohekohe
iiwi
akiapolaau
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42. How did the ancestral finch get to the Hawaiian islands?
======================================================================= Hawaiian honeycreepers web site: http://people.eku.edu/ritchisong/hawaiihoneycreepers.html ======================================================================= 43. How many species of Drosophila are found in Hawaii? In North America?
44. How many species of ancestral Drosophila probably arrived on the islands by wind?
45. What has allowed so many different species of Drosophila to evolve?
46. Describe two of the different courtship rituals used by these flies.
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47. Why is flying dangerous for an island insect?
48. What is unusual about the wings of the Hawaiian lacewing?
49. What is unusual about the wings of the Hawaiian crane fly? What does it eat?
50. Describe the twig caterpillar. How does it locate prey?
51. What is the effect of introduced predators on the native species that inhabit an isolated island?
52. How long ago did the Polynesians reach Hawaii?
======================================================================= CORRECTION: Recent redating of key sites in Hawaii put the age of first settlement at about 900 AD. This information was provided to us by Dr. Patrick Kirch, University of California, Berkeley. See On the Road of the Winds by Dr. Kirch for more information. ======================================================================= © Speer, Maxim and Strong
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53. Describe the techniques used by the Polynesians to build ocean-going canoes.
54. How are the leaves of the pandamus tree used?
55. Describe the Polynesian colonization of the Pacific. What did they use to find their way?
56. Describe the remains of the culture that developed on Easter Island.
======================================================================== Easter Island web site: http://www.pbs.org/wgbh/nova/easter/ David Attenborough further explains one possible explanation for the fate of Easter Islanders at: http://old.noob.us/miscellaneous/david-attenborough-explains-eastern-island/ ======================================================================== © Speer, Maxim and Strong
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Locator: New Zealand 57. How far did the Polynesians sail to reach New Zealand? When did they arrive in New Zealand?
58. What new challenges faced the Polynesians that colonized New Zealand?
59. How does New Zealand differ from the coral atolls and volcanic islands? How was New Zealand formed?
60. Describe the tuatara. What does it eat? Why is it unusual?
61. Describe the kiwi. Where does it live? In these New Zealand forests, the kiwi is the bird equivalent of what animal?
62. What does the kiwi eat?
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63. What birds, besides the kiwi, are ratites? Where are they found?
64. Describe the extinct moa. What did it eat? How do we learn about its diet or other features?
65. What two activities of the Maori people were responsible for the extinction of the moa by the 16th century?
======================================================================= ADDITIONAL INFO: In his book, Attenborough also explains that the Maori had a huge impact on the moa, using their skins, eggs and bones in addition to eating them for food. Skins were used for clothing; the big eggs became containers; the bones were used to make jewels, tools and weapon tips. The Maori also cleared the forests for home sites, thus reducing the suitable habitats for moa. All in all, the effects were so devastating that the moa were extinct within a few hundred years after the Maoris colonization of New Zealand. And, as Attenborough explains, so were about 44 other species. (page 265) ======================================================================= 66. How did other, more modern animals reach New Zealand after it was isolated?
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67. Describe the kea. What is it related to? Where does it live? What does it eat?
68. Describe the kakapo. Where does it live? What does it eat?
69. What are the three characteristics commonly found in island inhabitants?
70. What impact did the Polynesians have on the kakapo's population?
71. What impact did the European settlers have on the kakapo's population?
72. Where are the kakapo located now and why?
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73. Fill in the table with the impacts of imported animals on native island animals. Describe the types of problems these imported species created for native species. Imported Animals
Impacts on Native Species
Rats brought by Polynesians Predatory Animals brought by Europeans: Cats Stoats Ferrets
Herbivores brought by Europeans: : Possums Rabbits Red deer
74. Describe the takahe. What type of bird is it?
75. How many takahes are alive today? Where are they located? Why?
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LIVING PLANET EPISODE ELEVEN MATERIAL FOR YOU TO COVER Read the CONCEPTS section in the study guide for episode 11. Answer the Concepts Study Questions. Watch Video Episode 11 – The Open Ocean. Answer the Video Study Questions.
EPISODE 11 LEARNING OBJECTIVES To become acquainted with: 1. Ocean zones 2. Food chains of the open ocean 3. Variations of the Pacific Ocean floor 4. Ecology of shallow oceans near coasts: location, characteristics, life forms, and adaptations 5. Plankton and their importance to ocean inhabitants 6. Bony fish as compared to cartilagenous fish 7. Ecology of coral reefs 8. Ecology of open ocean communities 9. Ecology of kelp beds 10. Ecology of deep water communities (deep-sea) 11. Relationship between currents and nutrients 12. The Sargasso Sea 13. The Grand Banks of Newfoundland
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CONCEPTS FOR EPISODE 11 - THE OPEN OCEAN OCEAN ZONES In this episode, you will see a few of the communities that are found in the ocean. The oceans are divided into a number of zones, some of which Attenborough visits. Let's talk about the ocean bottom first. Imagine you are in your own personal submarine as you voyage across the bottom of the ocean. The bottom slopes gradually as you leave the shore and head toward open water. This gradual slope is called the continental shelf and is actually part of the continent. As you proceed further into the open ocean, you reach the edge of the continental shelf. Here, there is a sudden increase in the steepness of the slope; you are now on the continental slope. When your descent levels out again, you have reached the abyssal plain. Continue cruising away from shore. When you reach the middle of the ocean, you encounter a vast mountain range, with taller, steeper mountains than any on land. This is the midoceanic ridge. If you are exploring the Pacific Ocean, you may encounter deep canyons, called trenches, as well, especially around the edges of the ocean. During your voyage along the ocean floor, you have been traveling just above the benthic zone. Near the shore, light is able to reach the benthic zone, and in these regions, seaweeds and seagrasses may be found. Away from the shore, as the water gets deeper, the light can no longer reach the bottom. Thus, most of the benthic zone is in perpetual darkness, and, except in special circumstances (hydrothermal vents--see episode 1), all the organisms there either get their food from dead organic matter that falls down out of the lit regions above or prey on each other. The open waters above the ocean floor are called the pelagic zone. The pelagic zone is divided into two regions: the neritic zone and the oceanic zone. The neritic zone encompasses the water above the continental shelf. The oceanic zone includes the water above the continental slope, abyssal plains and midoceanic ridges. The neritic zone is richer than the oceanic zone. Because it lies above the continental shelf, the water is more shallow, and more of the bottom is reached by light. More light means more photosynthesis, and more animals that feed on the photosynthesizers. Also, the neritic zone receives large amounts of nutrients from the rivers that empty into the ocean in the coastal regions. This means that all those photosynthesizers have plenty of nutrients to grow, so more animals can be supported. The richness of the neritic zone supports the world's most productive commercial fisheries. Or did, until technologically advanced human beings managed to efficiently deplete many fish populations. You'll see this in episodes 11 and 12. Many of the communities that Attenborough visits in this episode are found in the neritic zone. Look for the coral reefs, kelp beds, and the Grand Banks in the videotape. The oceanic zone is the desert of the sea. This may seem like a contradiction in terms, but let us explain. Even in the parts near the surface that receive light, the © Speer, Maxim and Strong
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distance of these areas from land means that plant nutrients are low and that the microscopic algae that supply the food for all the animals cannot grow very rapidly. Thus, communities in the oceanic zone grow slowly because of low levels of plant nutrients, just as desert communities on land grow slowly because of low rainfall. Look for the Sargasso Sea in this episode as an example of a special oceanic zone community.
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OPEN OCEAN FOOD CHAINS In the open water of the oceans, all the organisms must either float or swim. The plankton are small organisms that are designed to float or are such weak swimmers that they cannot escape the ocean currents. Plankton is a general category for floaters. Floaters come in two specific subtypes: the phytoplankton (producers) and the zooplankton (consumers). In the oceans, most of the phytoplankton consists of tiny algae. They may be small, but they are present in enormous numbers, especially in the neritic zone, and together they produce enough organic matter to support all the rest of the organisms of the open ocean. The zooplankton of the oceans consists mostly of tiny animals, but some may be quite large, such as the jellyfishes. Many zooplankton feed on the phytoplankton, and others feed on other members of the zooplankton. Many of these animals are permanent members of the zooplankton, spending their entire lives feeding on phytoplankton or on each other. Other animals live as zooplankton for only part of their lives, such as larval crabs and fishes. Another important group of animals in the open waters of the ocean is the nekton. Examples of animals which belong to the oceanic nekton that you will see in the video include the squid, adult fishes (from the relatively small capelin to those very large and voracious predators, the tuna) and the whales. Keep in mind that all the animals, both zooplankton and nekton, no matter how large or small, are all supported by the enormous numbers of microscopic phytoplankton. Here’s a simple food chain for the open ocean:
KEYSTONE SPECIES The coral reefs are a good ecosystem to examine the concept of keystone species again. The corals themselves are the keystone species in this ecosystem. With the corals, this ecosystem is highly diverse. Without the corals, most of the organisms that live there would not be able to survive and the ecosystem would be radically different. References: Grzimek, Bernhard. 1984. Grzimek's Animal Life Encyclopedia. Vol. 5: Fishes II and Amphibians. Van Nostrand Reinhold, New York. Thurman, Harold V. 1988. Introductory Oceanography. 5th ed. Merrill, Columbus, OH. Watson, Lyall. 1981. Sea Guide to Whales of the World. Dutton, NY.
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CONCEPTS STUDY QUESTIONS FOR EPISODE 11: 1. Describe variation in the topography of the ocean bottom including the continental shelf, continental slope, abyssal plain, midoceanic ridge, and trenches.
2. Describe the typical open ocean food chain based on phytoplankton,
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VIDEO STUDY QUESTIONS FOR EPISODE 11: Species mentioned in this section: feather stars, horseshoe crabs 1. How much of the earth's surface is covered by water?
2. How does the floor of the ocean compare to the surface of the land?
3. Describe the variations that exist in the floor of the Pacific. In the tape, Attenborough begins at the Marianas Trench of the Pacific and travels eastward. [Note: he talks about 5 regions: (1) trench, (2) plain, (3) mountain range, (4) sand dunes, and (5) flanks of volcanic islands of Hawaii.]
4. What produces the large clumps of manganese that lie on the underwater sand dunes?
5. When did life begin? Where did it first appear?
6. Identify two ancient life forms that are found in the shallow, sunlit coastal oceans today.
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7. What are plankton? How do the photosynthetic plankton produce food? What is the base of all life in the seas?
8. Describe the feeding strategies used by some of the plankton-eating animals: Plankton-Eaters
Feeding Strategy
floating plankton (zooplankton)
Venus’s girdle
anemones
barnacles
crabs
9. Describe the manta ray. How big is it? What does it eat? How?
10. How large is the basking shark? What does it eat? How much?
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11. How large is the whale shark? What type of animal is it? What does it eat? What other fish are found around the whale shark and what do they eat?
12. Describe the gray reef shark. How is it adapted to living in the water? (Note: Attenborough uses the term “gristle” to mean “cartilage”. Sharks are cartilaginous fishes.)
13. Describe the bony fish. How do they differ from the sharks?
14. How fast can a tuna swim while hunting?
======================================================================= ADDITIONAL INFO. Tunas are one of the big, streamlined fish predators found in the open oceans. Unlike most fish, they are endotherms. They can raise their body temperatures as much as 12° C above the water temperature (about 22 degrees Fahrenheit). ======================================================================= 15. When did the toothed whales evolve? What are they descended from? [Also see the additional information that follows question 16.]
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16. Describe the narwhal. What is the function of its long tusk?
======================================================================== ADDITIONAL INFO: Whales come in two varieties: toothed and baleen. The toothed whales all have teeth (obviously). This group includes the dolphins, killer whale, narwhals, belugas and some very large whales such as the sperm whale. These whales are all predators, and their spiky teeth are excellent weapons for catching fish and other slippery animals. Toothed whales evolved from terrestrial carnivores about 50 million years ago. Baleen whales evolved from a common whale ancestor; scientists do not agree about when they evolved. Instead of teeth, the baleen whales have large plates hanging down from their upper jaws like fringe. They use the plates, or baleen, to filter their food from the water. They take large quantities of water into their mouths and force the water through the baleen, catching small fishes and other animals such as krill (a planktonic crustacean) on the plates. The humpback whale is a baleen whale; look for it eating capelins in the video. ======================================================================== Locator: Canadian Arctic 17. Describe the beluga. How do they communicate? Why do they congregate in large numbers?
18. Describe the walrus. What are they descended from? How are they adapted to life in the seas?
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19. Describe a coral reef. What do corals need in order to grow?
20. What are the features of a lagoon?
[Coral reefs were also covered in Episode 10.]
21. Briefly describe the different varieties of coral.
22. How do the coral organisms grow?
23. What terrestrial ecosystem is considered to be an equivalent to the coral reefs? Why?
24. Be able to describe the coral.
======================================================================== CLARIFICATION: In the video, Attenborough says that corals are "tiny anemone-like creatures" and refers to algae that live within their tissues. Coral polyps (the name for individual coral organisms) often contain algae, living in a symbiotic relationship. The algae photosynthesize during the day, providing the partners with food. At night, the coral polyp feeds by filtering small particles out of the water, thus providing the partners with food. Corals belong to the same group of animals as sea anemones. ======================================================================== © Speer, Maxim and Strong
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25. Describe the angler fish and the decoy fish. How do they catch prey?
26. Why do crabs frequently place sea anemones or sponges on their shells? How do the anemones and sponges benefit?
====================================================================== ADDITIONAL INFO: The interactions between these crabs and sponges and/or sea anemones are just a few examples of the many symbiotic interactions found within the seas. Here is one of our favorite examples. The cleaner wrasse is a fish that we call the "dentist-of-the-sea". It specializes in picking the parasites out of the mouths and off the gills of other fishes. It finds a prominent coral head which it uses as its cleaning station (dentist's office), then advertises by swimming in a particular pattern and by its striped appearance (you may now picture your dentist in a clown suit doing a hula dance outside her office). The wrasse's sometimes dangerous clients, such as barracuda and immense groupers, seem to be kept in line by the little guy's dance. They hover in one spot and open their mouths and gill covers so the wrasse can clean them. Once the cleaning station is "open", several fishes will queue up, patiently waiting their turn. (Just imagine how comfortable you would feel, knowing a predator is in line behind you.) So, where are the mutual benefits? The wrasse gets dinner; the fish gets its mouth and gills clean, which are hard to reach for a fish! Another symbiotic relationship occurs between certain sea slugs (nudibranchs) and algae. The sea slugs eat corals and keep their symbiotic algae. The algae provide the sea slugs with food. The algae gets nitrogen from the ammonia wastes excreted by the sea slug. (Remember the nitrogen cycle. In tropical waters, nitrogen is rare.) For more info, see: http://www.seaslugforum.net/factsheet/solarpow ======================================================================= Locator: Norway 27. Describe the kelp beds. What are the conditions of the kelp beds?
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28. Why are kelp beds considered to be equivalent to evergreen forests?
29. Describe the eider. What do they eat? How are they adapted to this community?
30. How does the lumpsucker deal with the problem of currents?
31. Where do kelp beds grow?
Locator: Australia Species mentioned in this section: sea urchin, goatfish, giant amphipod, hagfish, deep sea stars 32. Describe the leafy sea dragon. What does it eat?
33. Describe the "deserts" of the sea. What organisms live here?
34. Describe the garden eels. What do they eat?
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35. How does the blade fish elude predators?
36. Why does the cuttlefish burrow into the sand? What does it eat?
37. How far does light penetrate in the ocean waters?
38. What types of animals are found in deep, dark waters? [Note: This is the deep sea community. There is no true land equivalent to this community.]
39. Where does the food for this deep sea community come from?
40. Describe the flashlight fish and their adaptation to living in the dark, deep waters.
====================================================================== ADDITIONAL INFO: Flashlight fishes and many deep sea organisms have bacteria that live in specialized pouches on their bodies. These bacteria use a chemical process to give off light. This phenomenon is called bioluminescence. Check out these David Attenborough short videos about bioluminescence from his Blue Planet series: http://www.bbc.co.uk/programmes/p006v47r and http://www.bbc.co.uk/programmes/p006v478 ======================================================================= © Speer, Maxim and Strong
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41. What are the conditions on the floor of the deep ocean that animals have to cope with?
42. What does the tripod fish look like?
43. Water that is picked up by the waves of the ocean tend to circulate in the same place while the waves move on. What function does this circulation have?
44. How are deep currents formed?
45. Describe the deep currents of the Pacific.
46. Describe the deep currents of the Atlantic.
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47. Describe the Sargasso Sea. Where is it located? Why is this area largely barren? What life forms live here?
======================================================================= ADDITIONAL INFO: The center of the Sargasso Sea is 2000 miles west of the Canary Islands. It is an irregular oval-shaped area bounded within the 20-40 degrees North parallels (latitude) and the 35-75 degrees West meridians (longitude). (Reference: World Book Encyclopedia.) We have roughly sketched it on the map below. =======================================================================
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Locator: Grand Banks of Newfoundland Species mentioned in this section: shearwaters, gannets, seals, mackerel 48. Why are the coasts off Newfoundland fertile and productive?
49. What conditions promote the large numbers of phytoplankton (what Attenborough calls plants) in these waters?
50. Describe the breeding methods of the capelin.
51. What animals eat the capelin?
52. How are capelin gathered by the humpback whale? What is this technique called?
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53. What does the presence of the dead squid bodies signify? What happens to the great harvest of squid?
54. What does a squid do when it is hooked? [Note: this is the squid's escape mechanism that it uses to elude predators.]
55. What other fish comes in great numbers to the Grand Banks? Why?
56. What has been the impact of fishing on the animal populations of the Grand Banks?
======================================================================= ADDITIONAL INFORMATION: By the early 1990s, the cod and flounder fisheries on the Grand Banks had collapsed. The limits of turbot, ocean perch and other fish species were severely restricted, with drastic economic effects. Starting in 2011, scientists have reported recovery of haddock and partial recovery of cod. Other scientists are more cautious about future recovery, especially with the impacts of global warming. You can find more current info at: http://www.gov.nf.ca/exec/premier/gbanks.htm or ======================================================================= © Speer, Maxim and Strong
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LIVING PLANET EPISODE TWELVE MATERIAL FOR YOU TO COVER Read the CONCEPTS section in the study guide for episode 12. Answer the Concepts Study Questions. Watch Video Episode 12 – New Worlds Answer the Video Study Questions.
EPISODE 12 LEARNING OBJECTIVES To become acquainted with: 1. The problems of overpopulation and resource use 2. Changes caused by humans: domestication, cultivation, cities 3. Changes made in plants, animals and habitats as a result of human intervention 4. The concept of monocultures 5. Ecology of urban life: location, characteristics, life forms and adaptations 6. The spread of Oxford ragwort 7. The interdependence of organisms found in the Chincha and San Gallan Islands and the effects of humans on this community 8. Pollution 9. Deforestation and cultivation of rain forests 10. Advantages and disadvantages of dams 11. Three principles of the World Conservation Strategy
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CONCEPTS FOR EPISODE 12 - NEW WORLDS THE PROBLEMS ASSOCIATED WITH HUMAN POPULATIONS The world's population is much larger today than it was when this episode was made (Attenborough used the number 4 billion and the tapes were made in the early 1980s). As of 22:40 UTC on July 20, 2016, there were 7,339,034,137 humans on the earth. Thus, in about 35 years, more than 3.3 billion people have been added to the world's population. According to the estimates of the U.S. Census Bureau, the world's population will reach 8 billion by 2025 and 9 billion by 2042. Just imagine: nine billion people jammed on the surface of the planet. [Reference: http://www.census.gov ] ================================================================== AUTHORS' NOTE: To really comprehend the problem, most of us have to look at shorter time scales. The population of the world increased by 78,044,136 people in one year from 2015 to 2016. This does NOT mean that over 78 million babies were born. This means that almost 78 million babies were born IN EXCESS OF the number of babies that replaced the people who died in this time period. Or, as depicted below: 77,688,585 = # people born - # people died With rounding, this is roughly equivalent to: Per Day: 212,264 more people born than died Per Hour: 8,844 more people born than died Per Minute: 147 more people born than died This means that 294 more people were added to the population of this planet if you took two minutes to read and comprehend this note. ================================================================== Most of these people will be born in developing countries, places where the people today have a low standard of living. These countries will be hard pressed to feed and house any additional people, and it will be almost impossible to increase their standard of living. Growth in the human population puts stress on the environment. With more people to feed, more land must be cleared for the production of crops. More fishermen will go to sea, resulting in increased harvesting of commercial fishes. Where there is a natural resource that can generate money to buy food and other items, such as timber or minerals, it will be exploited more fully. All of these activities are carried out to the detriment of natural ecosystems.
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Thus, human overpopulation leads to environmental degradation. But in case you think that overpopulation in developing countries is the only cause of environmental problems, let's take a look at another kind of overpopulation that is found in the United States: resource overpopulation. Resource overpopulation is due to consumption of resources by each person. The effect one human being has on the environment depends on the amount of resources he or she uses. In the United States, on average, each person uses many times the resources of a person in a developing country like Rwanda or Afghanistan. For example, the U.S. population makes up 4.4% of the world's population, but we use 20% of the world's energy and produce 25% of the world's solid wastes. And all these resources we use are ultimately extracted from or have effects upon natural ecosystems. [Note: It is difficult to get good estimates on solid waste production but we used information from the World Bank.] A simplified schematic of the problem is:
Overpopulation Resource Depletion Environmental Degradation
CARRYING CAPACITY Biologists studying natural communities have introduced the concept of carrying capacity. The carrying capacity of an ecosystem is the number of individuals it can support without sustaining damage. The question we face today is: Have humans outstripped the carrying capacity of the planet? How many humans can be supported without endangering the ecosystems on which all life depends? We have seen throughout this series, both in the video episodes and the study guide, the types of effects humans have on ecosystems: Global Warming, Ozone Depletion, Overfishing, Deforestation, Species Extinctions. Do you think that humans have yet to reach their carrying capacity? Or have we already surpassed it? Please note: carrying capacity does NOT just apply to humans. There is a maximum number of deer that the Hill Country can support without sustaining damage. There is a maximum number of squirrels that can be supported in a forest. There is a maximum number of blue catfish that can live in Town Lake. ================================================================== Or, to use the words of a former student: The carrying capacity of a community is a reflection of how many organisms can live in that community based on the resources available to support it. Example: you cannot have 10,000 squirrels in an isolated pecan grove of 20 trees. ==================================================================
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SOLUTIONS? So, how do we solve these problems? Let's look first at the problem of human population growth. A population grows if the number of births per year exceeds the number of deaths. Thus, there are two ways to stop the population from growing: (1) decrease the number of births, or (2) increase the number of deaths. Option two is not a reasonable option for most people. After all, are you willing to kill off yourself and everyone you know just to control our population size? However, nature may use this option to solve the problem for us, whether we like it or not. Consider the Ebola virus or AIDS. These, or a new disease that we haven't heard of yet, could be the plague of the 21st century. For most of us, option one has to be the one we use if we are serious about controlling the problem. That option itself leads to serious questions. How will the number of births be decreased? Voluntarily? Involuntarily? Who gets to decide how many children you get to have? The People's Republic of China was until recently one of the countries of the world with a very high growth rate. The Chinese government has been successful at controlling population growth through their One Child Policy. Each couple is allowed to have only one child. Any additional children result in substantial financial and social penalties. The policy has been most successful in urban areas. In rural areas, it has been less successful, in part because rural families rely on the children to help with farming. Without access to the technology used by Western farmers, farming is a laborintensive business. Families with few children are unable to successfully farm their land. The Chinese government has recognized this problem, and has relaxed the One Child Policy in rural areas. Another problem that has emerged since the One Child Policy was begun is female infanticide. If a couple can only have one child, most couples prefer that the child be a son. Some couples, when their only child turns out to be a girl, neglect the girl so that she grows sick and dies. Then the couple can try again for a son. With the use of amniocentesis, a technique that allows some genetic defects and the sex of a fetus to be determined before birth, a couple can choose to abort female fetuses. Starting in 2015, China has begun the process of phasing out the One Child Policy. You can get more information at: http://www.bbc.com/news/world-asia-34665539 or search for “China One Child Policy” to get numerous articles. So think about an imaginary scenario. You now have the power to enforce population growth. What is your policy going to be? Now let's look at resource overpopulation. There is only one way to solve this problem: use less. These are some of the areas that Americans overuse resources, compared to other nations. We burn more fuel. We generate more wastes. We eat more food. We use more water. We buy more gadgets. We are a nation known for conspicuous consumption. © Speer, Maxim and Strong
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One campaign promoted in the United States to encourage us to reduce resource consumption is based on the slogan: Reduce, Reuse, Recycle. This means: (1) Reduce the amount of stuff you use by cutting down on purchases. Proponents suggest that you buy what you need, not what you want. (2)
Reuse the things you own instead of throwing them out when you're done. For example, instead of throwing out magazines you have read, you could take them to the library for others to read. Purchase shopping bags and use them at the stores instead of plastic bags or paper sacks.
(3)
Recycle materials such as aluminum cans, office paper, newspapers, plastic bottles, glass. These materials can be transformed into new products. For example, Polartec fleece is made using recycled plastic soda bottles.
Then, do one more thing. Close the loop. Buy recycled products whenever you can. There are many options available, from recycled paper products to carpet made from recycled plastic bottles. Help to create a market for those recycled products, so they don’t end up in landfills because there is no market. So, what are you willing to give up? What are you willing to do? If you were in control, what would your solution be? These are some of the tough decisions that need to be made NOW. Ignoring them is like being an ostrich with its head stuck in the sand as the lions creep up from behind. As citizens, you are in the position to make a difference. Attenborough discusses these issues in this final episode. As you watch the episode, watch for issues that deal with: (1) Human population growth, (2) Preserving biodiversity, (3) Land use problems, and (4) Pollution.
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PHOSPHORUS CYCLE The last nutrient cycle that we are going to discuss is the phosphorus cycle. Phosphorus is used by organisms to make nucleic acids (like DNA). It is also used to make phospholipids, which are a major component of the cell membrane of cells. The phosphorus cycle is different from either the nitrogen cycle or the carbon cycle because it does not have an atmospheric stage. The main form of phosphorus found in the environment is phosphate (PO4). Phosphates are found in soil, water and in sedimentary rocks. Remember that the growth of producers is limited by the availability of nitrogen and phosphorus. In nature, phosphorus is in short supply. Look at a bag of fertilizer. The ingredients list on the label will tell you how much nitrogen and phosphate is in the fertilizer. So, if you are a farmer and you want good crops, you use lots of fertilizer. Some of the fertilizer is taken up by the plants; some stays in the soil; some runs off when it rains and ends up in the water. The aquatic algae and plants now have LOTS of available nutrients and they grow and grow and grow. [Remember the algal bloom from Episode 8.] As their numbers increase, they use more and more oxygen at night. At some point, they use more oxygen than they produce. Then, the ecosystem collapses. Everything that needs oxygen dies. And so, the results are: no more algae, no more producers, no more snails, no more fishes. Here is a quick overview of the phosphorus cycle:
Reference: Smith, Robert Leo. 1992. Elements of Ecology, 3rd ed. HarperCollins, NY.
In this episode, Attenborough talks about guano which is a waste product produced (in this case) by guanay cormorants. Guano is also produced by bats. Large colonies of seabirds or bats produce large quantities of guano. Humans have used guano for fertilizers for thousands of years. In recent decades, however, the phosphate in fertilizer is made synthetically from phosphorus-containing rocks. Humans mine the rock, extract the phosphate, mix with nitrates and other nutrients and bag it up. As a result, the naturally slow cycling of phosphorus has been drastically accelerated. © Speer, Maxim and Strong
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CONCEPTS STUDY QUESTIONS FOR EPISODE 12: 1. The world population in 2016 was ____________________________ people. 2. The predicted world population in 2025 is ____________________________ people. 3. The predicted world population in 2042 is ____________________________ people. 4. Describe the kinds of environmental degradation caused by increased human populations.
5. Define resource overpopulation.
6. Explain how energy consumption and solid waste production in the United States compares to our percent of the total world population.
7. Define carrying capacity. Explain how you would know when the carrying capacity of a population had been exceeded.
8. Describe the two types of solutions for human overpopulation. Compare benefits and drawbacks of each solution.
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9. What is phosphorus used for in living organisms? by farmers?
10. Draw and describe the phosphorus cycle.
11. Explain how the use of phosphorus in fertilizers causes the phosphorus cycle to speed up.
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VIDEO STUDY QUESTIONS FOR EPISODE 12: 1. What forces have changed the surface of the earth?
2. Why are the poles cold?
3. What causes forests to be replaced by grasslands? What causes grasslands to be replaced by deserts?
4. How have animals adapted to hot conditions? to cold conditions?
5. How have the following humans managed to live in the various habitats without adapting: a. Eskimos
b. Indians in equatorial jungles
c. Bushman of South Africa
Locator: Middle East 6. What major change in human society occurred in the Middle East about 9,000 years ago?
7. Describe the early village remains that are found in the valley of Beda in Jordan.
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8. What type of plant was cultivated?
9. What meat was eaten by these people?
10. Where are caribou found? Where are reindeer found?
11. Describe the Lapp people of Scandinavia. How is the lifestyle of the Lapps related to the lifestyle of the reindeer?
Website on the Sami people:
http://boreale.konto.itv.se/samieng.htm
12. What have been the effects of the Lapps on the reindeer?
Locator: Britain (White Cliffs of Dover) 13. When did European herdsmen with domesticated stock move into Britain?
14. Describe the changes that man and his domesticated animals brought about in England.
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Locator: Norfolk Broads 15. How were the waterways and reed beds of eastern England created? (peat is partly decomposed moss--like sphagnum moss- that is dug up and burned for fuel)
16. How were the moors of England and Scotland produced? When? How did heather become predominant? What is the relationship between heather and grouse?
17. Where are the only places in inland Britain where natural habitats still exist? Why?
18. What did man do to the following animals that were once found in England? English Animal Human Impacts (What, Why and When?) brown bears
wolves
beavers
wild boar
elk (European elk = American moose)
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19. What animals were introduced into England?
20. What was the first animal probably brought to Britain by man?
21. What were aurochs?
Locator: Chillingham 22. Describe the Cheviot herds of cattle. Why are they still wild?
23. Describe the changes that have occurred in cattle as a result of selective breeding.
24. Describe the changes that have occurred in pigs as a result of selective breeding. Pigs descended from which animal?
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25. Describe the changes that have occurred in turkeys as a result of selective breeding. Where did turkeys originate?
26. Describe the changes that have occurred in chickens as a result of selective breeding. Where did chickens originate?
27. Where did the following common domesticated plants develop? Domesticated Plants
Place of Origin
potatoes peas beans rhubarb beet roots carrots 28. Which plant family has been the single most important food plant for man?
29. When was rice domesticated? Where?
30. When was wheat domesticated? Where?
31. How much of the arable land today is devoted to growing rice? How many people depend on rice?
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32. Which grass species is favored by the Western World?
33. How has selective breeding changed wheat?
34. What has been the impact of man's preferred monocultures on the communities that once lived on cultivated farmland?
35. What other great monoculture is a product of man?
======================================================================== CLARIFICATION: Even though Attenborough uses the urban environment as another example of a monoculture, this is really a misuse of the term. A monoculture is an agricultural or forestry term used for a plot of land planted with only one variety of a crop or a tree. The following are better examples of monocultures than a city: a corn field, a wheat field, your lawn, a golf course planted with one type of grass which is carefully weeded and fertilized, a pecan orchard, a tree farm or a pine plantation. ======================================================================== 36. What changes have occurred in dogs and cats, as a result of domestication?
Locator: Mt. Etna, Sicily 37. Where was the Oxford ragwort first found? How did it get to Britain? Describe the spread of the Oxford ragwort.
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38. How have these animals been affected by human activities? Animals
Human Impacts
sea otters
prairie dogs
acorn woodpeckers
osprey
kestrels
kittiwakes
swallows
insects
39. Describe the brown rat. Where did it originate? What problems do they cause for man?
Locator: New York City 40. Describe the impact of these human pollutants on the earth: a. rubbish (solid waste)
b. soap suds
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c. oil
d. fumes from engines and factories
Locator: Lakes of Scandinavia 41. What has happened to the lakes of Norway and Scandinavia as a result of pollution? to the forests of Germany?
Locator: Chincha and San Gallan Islands of Peru 42. What is guano?
43. Describe the chain of events that happened when the anchovies were overfished in the 1950s.
44. What is the relationship between anchovies, guanay cormorants and plankton?
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45. What is happening to the tropical rain forests today? Describe the deforestation and cultivation of the forests in South East Asia. What is its impact on the jungles?
46. How do the activities of the developed world affect the forests?
47. Describe the Albizia tree. Why is it a possible "ray of hope" for the survival of the forests?
48. Describe the dam at Itaipu on the borders of Paraguay and Brazil. What are the advantages of a dam like this? The disadvantages?
49. Why is this type of major reshaping of the land considered to be not as damaging as other forms?
50. Outline the three points of the World Conservation Strategy.
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