Genre Comprehension Skill Text Features Science Content Nonfi ction State the Purpose • Captions • Labels • Diagrams • Glossary Animal Life Cycles Scott Foresman Science 2.4 Standards Preview Standard Set 2. Life Sciences 2. Plants and animals have predictable life cycles. As a basis for understanding this concept: 2.b. Students know the sequential stages of life cycles are different for different animals, such as butterflies, frogs, and mice. ISBN 0-328-23504-0 ì<(sk$m)=cdfaej< +^-Ä-U-Ä-U 23504_CVR.indd Cover123504_CVR.indd Cover1 2/1/06 1:50:56 PM2/1/06 1:50:56 PM Life Sciences by Kristin Cashore 23504_CVR.indd Cover223504_CVR.indd Cover2 2/1/06 1:51:08 PM2/1/06 1:51:08 PM Vocabulary amphibian insect larva life cycle mammal pupa tadpole Picture Credits Every effort has been made to secure permission and provide appropriate credit for photographic material. The publisher deeply regrets any omission and pledges to correct errors called to its attention in subsequent editions. Unless otherwise acknowledged, all photographs are the copyright of Dorling Kindersley, a division of Pearson. ISBN: 0-328-23504-0 Copyright © Pearson Education, Inc. All Rights Reserved. Printed in the United States of America. This publication is protected by Copyright, and permission should be obtained from the publisher prior to any prohibited reproduction, storage in a retrieval system, or transmission in any form by any means, electronic, mechanical, photocopying, recording, or likewise. For information regarding permission(s), write to Permissions Department, Scott Foresman, 1900 East Lake Avenue, Glenview, Illinois 60025. 1 2 3 4 5 6 7 8 9 10 V010 13 12 11 10 09 08 07 06 23504_CVR.indd Cover323504_CVR.indd Cover3 1/6/06 4:03:06 PM1/6/06 4:03:06 PM All Animals Have Life Cycles by Kristin Cashore 23504_001-016.indd 123504_001-016.indd 1 1/6/06 4:08:29 PM1/6/06 4:08:29 PM 2 The Life Cycles of Living Things Living things grow and change. A kitten does not stay a kitten. It grows into an adult cat. A life cycle is the way a living thing grows and changes. All animals have life cycles. Cats have life cycles. 23504_001-016.indd 223504_001-016.indd 2 1/6/06 4:08:33 PM1/6/06 4:08:33 PM 3 Every life cycle has stages. At each stage, the animal looks different. All animals change size as they grow. Many animals also change shape. Some animals even change color! A caterpillar and a butterfl y are part of the same life cycle. 23504_001-016.indd 323504_001-016.indd 3 1/6/06 4:08:46 PM1/6/06 4:08:46 PM 4 Different Life Cycles Different animals have different life cycles. A mammal is one kind of animal. Mammals have hair or fur on their bodies. Skunks are mammals. Dogs and cats are mammals too. Giraffes are mammals. Their bodies have hair. 23504_001-016.indd 423504_001-016.indd 4 1/6/06 4:08:54 PM1/6/06 4:08:54 PM 5 Young mammals look a lot like their parents. Mammals grow bigger as they get older. Some mammals also change color as they get older. Elephants are mammals. They grow bigger as they get older. 23504_001-016.indd 523504_001-016.indd 5 1/6/06 4:09:02 PM1/6/06 4:09:02 PM 6 Young Insects and Amphibians An insect is an animal with three body parts and six legs. A ladybug is a kind of insect. Ants and butterfl ies are insects too. Young insects look very different from their parents. Insects change size, shape, and color as they get older. Ladybug eggs An adult ladybug 23504_001-016.indd 623504_001-016.indd 6 1/6/06 4:09:07 PM1/6/06 4:09:07 PM 7 An amphibian is an animal that lives part of its life in the water. It lives the other part of its life on land. Newts are amphibians. Frogs and toads are also amphibians. Young amphibians look different from their parents. Amphibians change size, shape, and color as they get older. How is the young newt (left) different from the adult newt (below)? 23504_001-016.indd 723504_001-016.indd 7 1/6/06 4:09:15 PM1/6/06 4:09:15 PM 8 What is the life cycle of a toad? A toad is an amphibian. It starts life as an egg. The egg hatches and a tadpole swims out. A tadpole is a very young toad or frog. A tadpole lives only in water. It has a tail, but it does not have legs. Soon the tadpole starts to change. It grows back legs. Then it grows front legs. Its tail starts to get smaller. A toad egg A young tadpole An adult tadpole 23504_001-016.indd 823504_001-016.indd 8 1/6/06 4:09:23 PM1/6/06 4:09:23 PM 9 Finally, the tadpole starts to look like a toad! An adult toad has four legs. It does not have a tail. It can live on land or in the water. The adult toad may lay eggs in the water. Then the life cycle starts over. An adult toad 23504_001-016.indd 923504_001-016.indd 9 1/6/06 4:09:31 PM1/6/06 4:09:31 PM 10 What is the life cycle of a horse? A horse is a mammal. Baby horses are called foals. Foals look like their parents. Foals can stand up an hour after they are born! A foal A young horse 23504_001-016.indd 1023504_001-016.indd 10 1/6/06 4:09:36 PM1/6/06 4:09:36 PM 11 A female foal grows into a fi lly. A male foal grows into a colt. Colts and fi llies look more like adult horses than foals. After two or three years colts and fi llies become adult horses. Then they can have foals of their own. An adult horse 23504_001-016.indd 1123504_001-016.indd 11 1/6/06 4:09:51 PM1/6/06 4:09:51 PM 12 What is the life cycle of a butterfl y? Many insects have life cycles that are four stages. A butterfl y is an insect. Its life cycle has four stages. A butterfl y starts life as an egg. Then a larva hatches from the egg. This is the next stage. A larva is a young insect. A butterfl y larva is called a caterpillar. butterfl y egg caterpillar pupa 23504_001-016.indd 1223504_001-016.indd 12 1/6/06 4:09:59 PM1/6/06 4:09:59 PM 13 The caterpillar turns into a pupa. Its wings start to grow. The pupa turns into an adult butterfl y in the fi nal stage of the life cycle. The butterfl y looks very different from the caterpillar! The adult butterfl y may lay eggs. Then the life cycle of the butterfl y starts over. young butterfl y adult butterfl y 23504_001-016.indd 1323504_001-016.indd 13 1/6/06 4:10:23 PM1/6/06 4:10:23 PM 14 What is the life cycle of a dragonfl y? A dragonfl y is an insect. Its life cycle has three stages. A dragonfl y starts life as an egg. The dragonfl y egg hatches. A young dragonfl y crawls out. It is called a nymph. The nymph looks a lot like an adult dragonfl y. It has three body parts and six legs. The nymph does not have wings. dragonfl y egg nymph 23504_001-016.indd 1423504_001-016.indd 14 1/6/06 4:10:36 PM1/6/06 4:10:36 PM 15 The nymph grows bigger. It grows two sets of wings. Finally, it becomes an adult dragonfl y! The adult dragonfl y may lay eggs. Then the life cycle of the dragonfl y starts over. adult dragonfl y 23504_001-016.indd 1523504_001-016.indd 15 1/6/06 4:10:43 PM1/6/06 4:10:43 PM 16 amphibian an animal that lives part of its life in water and part on land insect an animal that has three body parts and six legs larva a young insect life cycle the way a living thing grows and changes mammal an animal that has hair or fur on its body pupa the stage after the larva in some insects’ life cycles tadpole the second stage of a frog’s life cycle Glossary 23504_001-016.indd 1623504_001-016.indd 16 1/6/06 4:10:50 PM1/6/06 4:10:50 PM What did you learn? 1. What are some ways a mammal may change during its life cycle? 2. What are the three stages of a horse’s life cycle? 3. All animals grow and change. Describe how a class pet or one you have at home has grown and changed since you fi rst saw it. 4. State the Purpose Go back to the caption on page 7. What is its purpose? 23504_CVR.indd Cover423504_CVR.indd Cover4 1/6/06 4:03:06 PM1/6/06 4:03:06 PM . stay a kitten. It grows into an adult cat. A life cycle is the way a living thing grows and changes. All animals have life cycles. Cats have life cycles. 23504_001-016.indd 223504_001-016.indd. 4:03:06 PM1/6/06 4:03:06 PM All Animals Have Life Cycles by Kristin Cashore 23504_001-016.indd 123504_001-016.indd 1 1/6/06 4:08:29 PM1/6/06 4:08:29 PM 2 The Life Cycles of Living Things Living. Labels • Diagrams • Glossary Animal Life Cycles Scott Foresman Science 2.4 Standards Preview Standard Set 2. Life Sciences 2. Plants and animals have predictable life cycles. As a basis for understanding