Solway - Secrets of Animal Life Cycles

S CIENCE SECRET S

ANDREW SOLWAY

E-book published in 2012 by Encyclopdia Britannica, Inc., in association with Arcturus Publishing Limited, 26/27 Bickels Yard, 151-153 Bermondsey Street, London SE1 3HA. Britannica, Encyclopdia Britannica, and the Thistle logo are registered trademarks of Encyclopdia Britannica, Inc.

ISBN 978-1-61535-629-4 (e-book)

This edition first published in 2011 in the United States of America
by MARSHALL CAVENDISH BENCHMARK
An imprint of Marshall Cavendish Corporation

Copyright 2010 Arcturus Publishing Limited

This publication represents the opinions and views of the author based on Andrew Solways personal experience, knowledge, and research. The information in this book serves as a general guide only. The author and publisher have used their best efforts in preparing this book and disclaim liability rising directly and indirectly from the use and application of this book.

All rights reserved. No part of this publication may be reproduced, stored in a retrieval system, or transmitted in any form or by any means, electronic, mechanical, photocopying, recording or otherwise, without the prior written permission of the copyright owner.

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Picture researcher: Tom Humphrey

Photo acknowledgments: Alamy: p 11 (Bob Gibbons); Corbis: pp 15 (W. Wayne Lockwood, M.D.), 23 (MedicalRF.com), 25 (DLILLC), 27 (Jean Francois Istel/Sygma); FLPA: pp 20 (Suzi Eszterhas/Minden Pictures), 22 (Nigel Cattlin); Getty Images: pp 10 (Paul Zahl/National Geographic), 12 (Bianca Lavies/National Geographic), 13 (Nicole Duplaix), 19 (Image Source), 28 (Adrian Bailey); IStockphoto: p 5 (Eduardo Jose Bernardino); NHPA: pp 8 (Rich Kirchner), 26 (Stephen Dalton); Shutterstock Images: cover eggs (Vishnevskiy Vasily), cover bee (Seleznev Valery), cover and pp 1 chicks (Cheryl E. Davis), 14 (Nickolay Stanev), 16 (Dr Morley Read); Wikimedia: pp 7 (Yotcmdr), 24 (Mehmet Karatay).

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Library of Congress Cataloging-in-Publication Data

Solway, Andrew.

Secrets of animal life cycles / Andrew Solway.

p. cm. -- (Science secrets)

Includes index.

1. Animal life cycles--Juvenile literature. I. Title.

QL49.S669 2011

591.56--dc22

2009050538

1 3 6 5 4 2

Do your parents have pictures of you when you were a baby? If they do, how do you look? You probably look very different from the way you look now! You have changed a lot since you were born, and you will change in other ways as you grow and get older.

Life Changes

All animals change over time. They are born from their mother or hatch from an egg, they grow and become adults, then they get old and die. This is a life cycle.

When animals become adults, they are able to reproduce (produce young).

When the offspring (young) are born, they begin a new life cycle.

The human life cycle. Children are born and grow into adults, who reproduce and have more children.

Learning About Life Cycles

In this book, you will find out more about animal life cycles. As you read, you will learn secrets about how different animals are born, grow, reproduce, and die.

Why do some animals change completely as they grow up? Why are eggs so amazing? And what happens to animals when they die?

This little girl, her mother, and her grandmother are all at different stages of the human life cycle.

E XPERIMEN T

FAMILY CHANGES

Look for photos of yourself when you were a baby. How different do you look? Would you recognize yourself if no one had told you who was in the photo?

See if you can find pictures of your parents and other family members when they were young. Can you recognize them? Why or why not?

Some insects live only for a week. Mice live for just a few years. Humans, whales, and tortoises, however, can live for more than one hundred years.

Live Fast, Die Young

Animals that have short lives must cram everything into a short amount of time. Mice are adults at around six weeks old, and they produce their first young only three weeks later.

Other animals have even shorter lives. The pygmy goby, a small fish, lives an average of only fifty-nine days. Mayflies and some kinds of midge spend less than a day as adults.

Giant tortoises, such as this one from the Seychelles Islands, can live for more than 100 years. Some are said to approach 200 years in age.

Slow and Steady

Humans are among the longest-lived animals. However, we are not the record breakers. Giant tortoises can live for more than 170 years. They do not become adults until they are 20 or 25. Bowhead whales have been found with