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2 Photo Credits: Cover: Dave Watts/Nature Picture Library; 2 (b) Peter Arnold, Inc./Peter Arnold, Inc.; 3 (t) Masa Ushioda/Bruce Coleman, Inc., (br) David Chapman/Alamy, (b) David Fox/Photolibrary/Getty Images; 4 (br) Gil Lopez Espina/Visuals Unlimited; 5 (br) E & P Bauer/Bruce Coleman, Inc., (t) Peter Arnold, Inc./Peter Arnold, Inc; 6 (bl) Michael & Patricia Fogden/Corbis, (br) Peter Arnold, Inc./Peter Arnold, Inc., Inc.; 7 (c) Chase Swift/Corbis, (inset) Alan G. Nelson/Animals Animals - Earth Scenes; 8 (b) Konrad Zelazowski/Alamy; 9 (tc) David Chapman/Alamy, (b) David Fox/Photolibrary/Getty Images; 10 (cl) Brad Mitchell/Alamy Images, (b) Robert W. Domm/Visuals Unlimted; 11 (c) Paul A. Souders/Corbis; 12 (b) Hanne & Jens Eriksen/Nature Picture Library; 13 (tl) Dietmar Nill/Nature Picture Library, (tr) Staffan Widstrand/Nature Picture Library, (b) M. Watson/Ardea; 14 (bl) Bernard Castelein/Nature Picture Library; 15 (tr) Georgette Douwma/Nature Picture Library, (bl) Jennifer Loomis/Animals Animals - Earth Scenes; 16 (t) Bob Cranston/Animals Animals - Earth Scenes; 17 (t) Nigel Bean/Nature Picture Library, (b) Arthur Morris/Corbis, (cr) Staffan Widstrand/Nature Picture Library; 18 (l) Michael Habicht/Animals Animals - Earth Scenes,(r) Ray Richardson/Animals Animals - Earth Scenes; 19 (cr) M. Watson/Ardea; 20 (b) Paul A. Souders/Corbis; 21 (b) Gianni Dagli Orti/Corbis; 22 (bc) Paul A. Souders/Corbis; 23 (cl) Jeff Gage/Florida Museum of Natural History, (t) SuperStock; 24 (br) David Cavagnaro/Visuals Unlimited, (bl) Patti Murray/Animals Animals - Earth Scenes; 25 (inset) Kevin Schafer/Corbis, (bl) D.Robert & Lorri Franz/Corbis,(br) Carol Havens/Corbis, (tr) Ken Lucas/Visuals Unlimited, (tc) DK Limited/Corbis; 26 (c) Gianni Dagli Orti/Corbis; 27 (br) Hulton Archive/Getty Images; (b) Ron Testa/The Field Museum. If you have received these materials as examination copies free of charge, Harcourt School Publishers retains title to the materials and they may not be resold. Resale of examination copies is strictly prohibited and is illegal. Possession of this publication in print format does not entitle users to convert this publication, or any portion of it, into electronic format.

3 Copyright by Harcourt, Inc. All rights reserved. No part of this publication may be reproduced or transmitted in any form or by any means, electronic or mechanical, including photocopy, recording, or any information storage and retrieval system, without permission in writing from the publisher. Requests for permission to make copies of any part of the work should be addressed to School Permissions and Copyrights, Harcourt, Inc., 6277 Sea Harbor Drive, Orlando, Florida Fax: HARCOURT and the Harcourt Logo are trademarks of Harcourt, Inc., registered in the United States of America and/or other jurisdictions. Printed in Mexico ISBN-13: ISBN-10:

4 basic needs adaptation natural selection Basic needs are the things that living things need to survive. Basic needs include food, water, air, and shelter.

5 An adaptation is a body part or a behavior that helps a living thing survive. Sharp teeth are an adaptation that helps an alligator catch its food. Natural selection is the process by which the best adapted organisms survive the best.

6 The main idea is what the text is mostly about. Details tell more about the main idea. Look for details about different basic needs and how living things meet them. All living things have the same basic needs. Basic needs are things a living thing needs to live and grow. These basic needs are food, water, shelter, and air. Living things get food in different ways. Plants make their food. Animals get food by eating plants or other animals. Humans also get food by eating plants and animals.

7 Plants get water from rain. Most animals drink water. Some get it by eating foods with water in them. Shelter takes many forms. Plants may grow in protected spots. Animals find shelter in different places. Some build or dig their own. List the four basic needs. Tell how you meet each one.

8 To meet their needs, plants and animals have adaptations. An adaptation is a body part or behavior that helps a living thing survive. Animals have many adaptations. One is body covering. Different kinds of feet are also adaptations. They help animals move. Some animals have long tongues or legs. Sharp beaks, teeth, or claws can help animals catch or eat food.

9 Behavior can also be an adaptation. Some animals migrate. This means they travel between summer and winter homes. Other animals hibernate, or are inactive, through winter. These adaptations help animals survive cold months when food is hard to find. Name three examples of adaptations.

10 Have you ever looked at a litter of kittens? Kittens with the same parents look alike in many ways. But each kitten also looks different. Every population has differences. Individual differences are important. Differences are what make one organism better suited to an environment than another individual. For example, what if a plant were taller than the other plants near it? That plant might get more sunlight, and so it would have more energy. That plant might be better able to reproduce. The plant could pass the tallness trait to its offspring.

11 Another example of adaptation is the peppered moth. It is shown in the pictures above. Once, most of the moths were light gray. They were able to blend in with their environment. This helped them hide from birds that would eat them. Then people built many factories. The soot from the factories darkened the tree trunks. The light gray moths were easier for birds to see. The dark gray moths blended with the dark bark. The moths are an example of natural selection. This is a process that enables living things with favorable traits to survive in their environment. Why might differences be a good thing?

12 All plants and animals follow a cycle of life. This cycle has different parts. First a living thing sprouts, is born, or hatches. Next it grows into an adult. Then it may reproduce. Last it dies and decays.

13 Living things must meet their basic needs to complete this cycle. If they cannot, they may die before they reproduce. If this happens to all members of a species, this kind of living thing will die out. What parts make up the cycle of life? 1. Animals have in order to meet their basic needs. 2. Types of teeth or feet are examples of adaptations to. 3. Migration and are examples of adaptations in behavior. 4. Animals can only complete their if they meet their basic needs.

14 instinct hibernation migration learned behavior An instinct is a behavior that an animal begins life with. Knowing how to build a nest is an instinct that birds have.

15 Hibernation is an inactive state. Hibernation helps this bat survive the winter. Migration is the movement of animals from one place to another and back. A learned behavior is a behavior that an animal does not begin life with. Tiger cubs learn to hunt from their mothers.

16 The main idea is what the text is mostly about. Details tell more about the main idea. Look for details that tell how animals meet their basic needs. Animals begin life knowing how to do many things. Spiders know how to spin webs. Zebras know that living in herds keeps them safe. Many birds know how to build nests. These behaviors are called instincts. An instinct is a behavior that an animal begins life with. It helps the animal meet its needs. Why is spinning a web called an instinct?

17 Many animals live where winters are cold. Often they know by instinct how to get ready for winter. They eat more. They find or build shelters. They hibernate there. During hibernation, an animal s normal body activities slow. Its heart barely beats. Its breathing almost stops. And its body temperature drops. A hibernating animal uses little energy. It lives all winter on fat stored in its body. Tell how animals that hibernate get ready for winter.

18 Migration is another instinctive behavior. Migration is the movement of animals in a group from one place to another and back. Animals migrate for different reasons. They may move for more food. They may move to a better climate. Caribou and whales migrate. They migrate each year at about the same times. These migrations depend on the seasons. Explain why some animals migrate. Gray whale Sandpiper Arctic tern Caribou 0 2,000 4,000 6,000 8,000 10,000 12,000 14,000 16,000 Migration Distances (in kilometers) 18,000 20,000

19 Animal Migration Routes

20 Many animals rely on instinctive behaviors to meet their needs. But some animals also have learned behaviors. A learned behavior is learned after birth. Other animals usually teach young animals learned behaviors.

21 Most mammals care for their young. Mammal mothers teach their young how to get food. They may teach them how to stay safe. Sometimes both parents teach their young. Some animals learn behaviors from people. Dogs can learn not to bark. Horses can learn to obey their riders. These are learned behaviors. Tell the difference between an instinct and a learned behavior. 1. Animals use both and learned behaviors to help them meet their needs. 2. is an instinctive behavior. It helps animals survive winter by using little energy. 3. During, animals may travel very long distances to reach warmer climates. 4. are often taught to younger animals by their parents.

22 fossil extinction A fossil is what is left of a plant or animal that lived long ago. Footprints or bones can be fossils. The bones of this dinosaur are fossils.

23 Extinction means that a kind of plant or animal has died out. Woolly mammoths became extinct about 30,000 years ago.

24 When you compare and contrast, you tell how things are alike and different. Look for ways to compare and contrast animals and plants of long ago with those of today. Fossils are the remains of plants or animals that lived long ago. Scientists study fossils to learn about animals and plants from the past. Footprints in mud are one kind of fossil. Over a long time, the mud hardens into rock. Bones are also a kind of fossil. Fossils can give clues about an animal s size. They can also show how an animal moved. Scientists compare fossils with the footprints and bones of animals today. This helps them understand how animals have changed.

25 Fossils help scientists link animals of the past to those of today. Some animals, such as turtles, have changed very little. Some animals, like camels, have changed a lot. Others, like dinosaurs, are no longer living. Tell how all fossils are alike and different.

26 Plant parts also formed fossils long ago. Leaves fell into mud. They made prints. Over time, the mud turned to rock. Like animals, many plants are no longer living. Scientists learn about them by studying their fossils. They learn how plants have changed over time.

27 Petrified wood is a kind of plant fossil. It is wood that feels like a rock! Scientists can learn about trees from long ago by studying petrified wood. Many kinds of plants have survived. Some of them, like the ginkgo tree, have not changed much. Some of them have changed a lot. Plants are still changing. Sometimes scientists and farmers change plants, too. They are trying to make plants that will survive in certain conditions. Tell how plant fossils are like animal fossils.

28 Many plants and animals are now extinct. Extinction means that a kind of plant or animal has died out. Plants or animals can become extinct when their habitat changes. Plants may die if their habitat becomes drier or colder. If this happens animals must move or they will die, too. Animals may also become extinct if there is not enough food.

29 People may also cause extinction. They may change the environment. This can cause animals to lose their homes. The animals may no longer have a place to find food. What are different ways an animal can become extinct? 1. Scientists study to learn about both plants and animals from long ago. 2. A fossil can be a print in mud or a. 3. Changes in an animal s habitat and food supply can both cause.

30 GLOSSARY adaptation (ad uhp TAY shuhn) A body part or behavior that helps an organism survive basic needs (BAY sik NEEDZ) Food, water, air, and shelter that an organism needs to survive extinction (ek STINGK shuhn) The death of all the members of a certain group of organisms fossil (FAHS uhl) The remains or traces of a plant or animal that lived long ago hibernation (hy ber NAY shuhn) A dormant, inactive state in which normal body activities slow instinct (IN stinkt) A behavior that an animal begins life with learned behavior (LERND bee HAYV yer) A behavior that an organism doesn t begin life with migration (my GRAY shuhn) The movement of animals from one region to another and back natural selection (NACH uhr uhl suh LEK shun) A process in which the healthiest oganisms in an ecosystem are able to survive and reproduce

31 1. Identify four basic needs that all animals have and describe the importance of each. 2. Explain how adaptations, instinctive behaviors, and learned behaviors help animals meet their basic needs. Make a model of an animal that has become extinct. 1. Give several reasons explaining why some animals disappear forever. Speculate why the animal you modeled may have disappeared. 2. Explain how scientists learn about animals that disappeared from Earth millions of years ago. Go with a family member to look for animals in your neighborhood. Observe their behaviors. Describe which behaviors you think are instincts, and which are learned behaviors. Explain why you think as you do.

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