all animals have life cycles

Students know the sequential stages of life cycles are different for different animals, such as butterflies, frogs, and mice... amphibian insect larva life cycle mammal pupa tadpole P

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

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Life Sciences

by Kristin Cashore

amphibian

insect

larva

life cycle

mammal

pupa

tadpole

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ISBN: 0-328-23504-0

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All Animals Have

Life Cycles

by Kristin Cashore

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.

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

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

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.

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

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)?

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

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

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

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

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

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

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

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

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

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?