Animal Groups and What Animals Eat

You can start learning about animal bodies by looking at yourself. Point to a part as you say its name.

From head to toes

Your head has hair, a face, eyes, ears, a nose and a mouth. Your teeth and tongue are inside your mouth. Your neck joins your head to your body.

Below your neck are your shoulders and chest. Your belly, or tummy, is at the front. Your back is behind you. Your legs join your body at your hips.

Follow one arm down from your shoulder. It bends at your elbow. Your wrist joins your arm to your hand. Each hand has 4 fingers and a thumb. Follow one leg down from your hip. It bends at your knee. Your ankle joins your leg to your foot. Each foot has 5 toes. Places where your body bends are called joints.

To label a drawing, write a body part's name beside it. Draw a line from the word to the right part. For “elbow,” follow the arm to its bend. Stop your line there. A knee label belongs on the leg's bend.

Five ways to find things out

Your senses tell you about the world around you.

Imagine holding a ripe peach. Your eyes see its color. Your fingertips feel its fuzzy skin. Your nose smells it, and your tongue tastes its juice. Your ears might hear juice drip onto a plate. One thing can give you clues through several senses.

Touch works through skin all over your body. You can feel a sleeve against your arm or sand under your feet. Your fingertips are especially good at feeling small bumps.

Your senses help keep you safe, too. You can hear a car coming or smell smoke. Only taste or sniff something new when a grown-up says it is safe.

Other animals have senses. A dog uses eyes to see and ears to hear, just as you do. Its nose can pick up smells that you cannot notice.

People are animals. So are cats, fish, frogs, birds and insects. Animals do not all have fur or walk on legs.

Look at the same part

To compare means to find what is alike and different. Choose one feature, such as legs. Look at that feature on both animals before choosing another.

You have a head, eyes, a mouth and a body. Many other animals have these parts, too. Some have parts you do not have: wings, fins, tails, horns or shells. A bird takes food in through its beak. You take food in through your mouth. Different-looking parts can do the same job.

Animals have different numbers of legs. People and birds have 2. Cats, cows, frogs and lizards have 4. Insects have 6, and spiders have 8. Snakes, fish and worms have none. A bird resting on a branch might hide one leg. Look at another picture before deciding a part is missing.

Look at the covering

An animal's body covering is what covers its outside. Your skin has some hair. A cat has fur, a bird has feathers, and a snake has scales. Most fish have scales, too. A frog has smooth, damp skin. A turtle also has a hard shell.

Here is a comparison of a duck and a cat. Read across each row to compare the same feature.

Both animals have a head, 2 eyes, a body and legs. The duck also has wings. The cat has whiskers.

Compare an animal with yourself

Think of a monkey. You both have eyes at the front of your head. You both have ears and hands that can hold things. A monkey has much more hair than you do. Most monkeys have a long tail, too.

You could say, “We both have hands, but I do not have a tail.” Naming the feature makes your comparison clear. “We look different” leaves your listener wondering which part you mean.

You can put animal pictures into groups by looking at their bodies. This is called sorting. A clear rule tells you where each picture belongs.

Ask a yes-or-no question

Try “Does it have legs?” Everyone can look for legs and check. “Is it nice?” is not a useful rule. People may give different answers. “Is it big?” is unclear unless you say what you compare it with.

Sort these 6 pictures: cow, robin, goldfish, horse, duck and snake.

1. Look at the cow. It has legs, so put it under “Yes.”
2. Check each remaining animal in the same way.
3. Read each group and check its pictures.

There are 4 pictures under “Yes” and 2 under “No.” Together that makes 6. Check that each name appears once, too. Now split the animals with legs again: robin and duck have 2 legs; cow and horse have 4.

You can sort the same pictures a different way. With “Does it have feathers?” robin and duck go under “Yes.” Cow, goldfish, horse and snake go under “No.” The animals stay the same. The rule changes their groups.

Use two circles

Draw two circles with a shared middle. Label one “Can fly” and the other “Has feathers.” Check both rules for each animal. Give every picture one place, including pictures outside both circles.

• An eagle can fly and has feathers. Put it in the shared middle, called the overlap.
• A bat can fly but has no feathers. Put it in the flying circle, away from the overlap.
• A penguin has feathers but cannot fly. Put it in the feather circle, away from the overlap.
• A dog fits neither rule. Put it outside both circles.

Gently feel the middle of your back. The row of small bones there is your backbone. It helps hold you up and lets you bend and twist.

Animals with a backbone are called vertebrates. A dog has one inside its body. So do a fish, a frog, a snake and a bird. You are a vertebrate, too.

Five groups to learn

We sort animals with backbones into 5 big groups. Their bodies give us clues.

A gill takes oxygen from water for an animal to breathe. Lungs take oxygen from air. Oxygen is a gas that animals need to stay alive. A fish can breathe underwater with its gills. A swimming mammal must come up for air.

Use body clues

Look at an animal's covering first. Then find out how it breathes and how its young start life. These clues help you find the group.

An animal's home is not enough. A goldfish, frog, turtle, penguin and whale can all use water. Yet they belong to 5 different groups. The goldfish has gills. The penguin has feathers. The whale breathes air and feeds its babies milk.

Animals without backbones

Worms, spiders, insects, snails, crabs and jellyfish have no backbone. They are animals, but they do not belong to these 5 groups. A butterfly has wings, but it is not a bird. A starfish lives in the sea, but it is not a fish.

A backbone is inside the body. You may not see it in a photo. A book showing the bones can help you check.

A goldfish swims past a tadpole in a pond. They both live in water, but the tadpole will grow into a frog. The goldfish will stay a fish.

Fish breathe with gills

Fish live in water. Their gills take oxygen from the water. Fins and a tail help them swim. Most fish have scales covering their bodies. Salmon, tuna, sharks and seahorses are fish.

Most fish lay small eggs in water. Some, including guppies and some sharks, have live babies. So you need more than the egg clue to recognize a fish.

A shark has fins and gills, so it is a fish. An eel looks long and thin like a snake. It also has fins and gills: it is a fish, too.

Amphibians begin and grow

Frogs, toads, newts and salamanders are amphibians. Many start life in water and later use land. Most have smooth, damp skin with no scales. A toad's skin is bumpier and drier than a frog's. It still has no scales. Amphibians need damp places so their skin does not dry out.

Watch a pond frog grow, step by step.

1. The mother lays soft eggs covered in jelly. A clump of these eggs is called frogspawn.
2. A tadpole hatches. It has gills and a tail. It swims in the pond.
3. Back legs grow, then front legs grow. The tail gets smaller.
4. The young frog now has 4 legs and lungs. It can breathe air and hop onto land.

Grown frogs and toads breathe with lungs. Their damp skin also takes in oxygen from air or water.

Use more than legs

A frog and a lizard both have 4 legs. Their skin tells them apart. The frog has smooth, damp skin. The lizard has dry scales and belongs to the reptiles.

A fish and a tadpole both have gills. Watch what happens as they grow. The fish keeps its gills and stays in water. The tadpole grows legs and lungs as it becomes a frog.

A turtle and a duck can both swim. Both breathe air, and both lay eggs. Look at their coverings to tell their groups apart.

Reptiles have dry scales

Snakes, lizards, turtles, tortoises, crocodiles and alligators are reptiles. Their skin has dry scales. Turtles and tortoises also have a hard shell.

Reptiles breathe air with lungs. Most lay eggs with tough shells on land. Some snakes and lizards have live babies instead. A sea turtle swims in the ocean, but it comes up to breathe. The mother comes onto a beach to lay eggs in sand.

Many lizards and snakes lie in the sun to warm up. They use heat from around them to warm their bodies. When they get too warm, they can move into shade.

Birds have feathers

A robin, duck, penguin and ostrich are all birds. Birds have feathers, a beak, 2 wings and 2 legs. They breathe air with lungs. All birds lay eggs with hard shells. Many build nests and sit on their eggs to keep them warm.

Feathers are a strong clue. Birds are the only living animals with feathers. A bird can have scales on its feet as well, so look at the whole body.

Work out the penguin's group

A penguin swims with its wings and cannot fly. Check its body clues.

1. Does it have feathers? Yes.
2. Does it have a beak? Yes.
3. Does it lay eggs with hard shells? Yes.

Those clues fit a bird. Flying is something many birds do, but it is not something every bird does. Ostriches, emus and kiwis are birds that cannot fly, too.

The lung and egg clues can fit both groups. Feathers show why a penguin belongs with birds, while a turtle belongs with reptiles.

You belong to the same animal group as a mouse and an elephant. All of you are mammals. Mammals can look very different, so look for their body clues.

Hair, lungs and milk

Mammals have hair or fur and breathe air with lungs. Their mothers make milk to feed their babies. A calf, puppy and baby whale all drink their mother's milk.

Most mammals have live babies. A baby grows inside its mother until it is born. You have hair, breathe with lungs and were born alive. Human mothers can make milk for babies. These are your mammal clues.

Dogs, cats, horses, cows, monkeys and people are mammals. A tiny mouse and a huge elephant belong together because of these clues, even though their sizes differ.

Mammals in surprising places

Whales and dolphins live in the sea. They breathe air through a blowhole on top of the head. Their babies are born alive and drink milk. Grown whales and dolphins have very little hair, or none. Their breathing and babies help you find their group.

Bats are mammals that fly by flapping their wings. Their bodies have fur, and their babies drink milk. Birds have feathers. A bat's wings do not turn it into a bird.

Mammals that lay eggs

A platypus has fur and lays eggs. When its babies hatch, the mother feeds them milk. An echidna does this, too. They are mammals even though they hatch from eggs.

This is why we say most mammals have live babies. The egg clue alone would put the platypus in the wrong group. Its fur and milk fit the mammals.

A baby in a pouch

Kangaroos and koalas are mammals with pouches. A baby kangaroo is called a joey. It is born very tiny. It climbs into its mother's pouch and drinks milk while it grows there. The pouch carries and protects the young mammal.

Some animals can fool you at first. A seahorse has “horse” in its name. A salamander looks a little like a lizard. Body clues help you sort them.

Check the clues together

Ask about the covering, breathing and babies. Feathers tell you that an animal is a bird. Among animals with backbones, hair or fur tells you it is a mammal. Other clues may need to work together.

“Lays eggs” fits birds, most fish, many amphibians and most reptiles. It also fits a platypus. You need another clue to choose between those groups.

Work out a whale's group.

1. Its smooth body has almost no hair to see.
2. It comes up for air and breathes with lungs.
3. Its babies are born alive and drink milk.

The lungs and milk match mammals. You can explain, “A whale is a mammal because it breathes air and feeds its babies milk.”

Sort a collection

Put these 8 pictures into the 5 groups: goldfish, frog, snake, robin, dog, shark, penguin and whale.

There are 2 fish, 1 amphibian, 1 reptile, 2 birds and 2 mammals. That makes 8 animals. Read each name again to check that it appears once in the right group.

Look past a name or a movement

A seahorse has fins and gills: it is a fish. A starfish and a jellyfish have no backbone: neither is a fish. A salamander has damp skin without scales: it is an amphibian. A sea turtle has scales and lungs: it is a reptile.

A picture may hide a useful clue. You cannot see a whale making milk in every photo. Find out about its young in a book or ask a grown-up. Then use what you learn to explain its group.

Animals get food by eating. Some eat plants, some eat other animals, and some eat both. We have a name for each kind of eater.

Three food groups

A herbivore eats plants. Plant foods include grass, leaves, fruit, roots and seeds. Cows, sheep, horses, rabbits, deer, giraffes, elephants and koalas are herbivores. “Herbi-” can remind you of a herb, which is a plant.

A carnivore eats other animals. Lions, tigers, wolves, cats, owls, eagles, sharks and snakes are carnivores. Insects, worms and fish count as animals, too. A frog catching flies and a penguin eating fish are both eating animal food.

An omnivore eats both plant food and animal food. Pigs, chickens, brown bears and raccoons are omnivores. “Omni-” means all: here it helps you remember both kinds of food.

People are omnivores, too. Our bodies can use foods from plants and animals. Some people choose meals without meat. That choice does not change the animal group people belong to.

Sort by grown-up food

A calf drinks milk, but a grown cow eats grass. We call cows herbivores because of their grown-up food. Use what an animal usually eats as a grown-up when you sort it.

Try this collection: lion, cow, sheep, brown bear, rabbit, owl and pig.

There are 3 herbivores, 2 carnivores and 2 omnivores: 7 animals altogether. An animal that eats both kinds goes in the omnivore group once.

One animal can have two group names

A cow and a lion are both mammals. Their food groups differ: the cow is a herbivore and the lion is a carnivore. Body groups and food groups answer different questions.

Size does not settle diet. An elephant is a huge herbivore. An owl is much smaller and eats animals.

An animal's mouth helps it get and eat food. Look at its shape, then think about the job that shape can do.

Teeth do different jobs

Cows, horses and sheep have wide, flat back teeth. These grind plants into small, soft pieces. Rabbits also have sharp front teeth that snip grass and leaves.

Lions, wolves and cats have long, pointed teeth to grab and hold food. Sharp back teeth cut meat. People and bears have a mix of teeth for different foods. Move your tongue gently over your own teeth. Your front teeth are thinner than your wide, bumpy back teeth.

Beaks fit food, too

Birds have no teeth. A beak does the food job instead.

• An eagle's or owl's sharp, hooked beak tears meat.
• A finch's or sparrow's short, thick beak cracks seeds.
• A hummingbird's long, thin beak reaches nectar inside flowers.
• A duck's wide, flat beak scoops food from water.

Nectar is a sweet liquid made by flowers. It is plant food. A beak's shape can help you guess which food a bird can reach or break apart.

Work from shape to food

Imagine a bird with a hooked beak and sharp, curved claws.

1. The claws can grab other animals.
2. The hook can tear meat into pieces.
3. These jobs suggest that the bird eats animals. It is probably a carnivore, like a hawk.

Then check what the bird really eats by watching or reading about it. A mouth is a clue, and the food gives you the answer.

Other parts help with feeding. A frog catches insects with its sticky tongue. An elephant pulls leaves with its trunk. A giraffe's long neck helps it reach leaves high in a tree.

Watch a bird on the ground and then in the air. One animal can move in several ways. Different parts help with different movements.

Parts that help animals move

Animals move to find food, water and safe places. They also move to get away from danger. Legs help animals walk, run, hop and climb. Wings help many animals fly. Fins and tails help fish swim.

Burrowing means digging into the ground. A mole's broad paws move soil aside. A snake has no legs. Its body moves against the ground to push it along.

More than one way

A duck walks on legs, swims with webbed feet and flies with wings. A frog hops on land and swims in water. You can walk, run, climb, jump and swim. You run on 2 legs; a dog runs on 4.

The cheetah is the fastest land animal. It runs on 4 long legs. A whale swims and a bat flies, but both are mammals, just like the cheetah. Movement does not choose the body group.

Flying and gliding

Birds and bats flap their wings to fly. A flying squirrel spreads flaps of skin between its legs. It glides from tree to tree without flapping wings.

Wings can have other jobs. A penguin uses its wings like flippers underwater. An ostrich spreads its wings to help it balance and turn while running.

A journey with the seasons

Some animals make long journeys at the same time each year. This is called migration. Many geese and swallows leave cold places before winter. They travel toward warmer places where they can find food, then return in spring.

A body part can help an animal get food, stay warm or escape danger. To explain how it helps, name the part and its job.

Protection and hiding

A turtle's hard shell protects its body. Some turtles tuck their heads inside it. Porcupine quills and hedgehog spines are sharp. They make an animal harder for an attacker to bite. Horns and hooves can help animals fight back.

Camouflage helps an animal blend into its surroundings. A polar bear's white fur is hard to spot against snow. A tiger's stripes break up its shape among tall grasses.

An owl's eyes and ears help it find mice at night. A rabbit's long ears help it hear danger. Its eyes sit on the sides of its head, helping it see around itself.

Keeping warm and saving energy

Thick fur helps a polar bear keep warm. Whales and seals have a thick layer of fat called blubber. It helps keep them warm in cold water. Birds fluff their feathers when it is cold.

Some animals hibernate through winter. Their bodies slow down a lot and use very little energy. They may wake for short times. Hedgehogs, groundhogs and many kinds of bats hibernate.

Animals are born or hatch with parts like their parents' parts. A turtle hatches with its shell. A baby porcupine's soft quills soon harden. Needing protection does not make an animal grow a new kind of part.

Copy a useful job

People copy animal parts when they design things. A bike helmet has a hard outside that protects your head, like a shell. Swim fins push water, like a duck's webbed feet.

Here is a way to design something for rain.

1. Name the problem: rain can make your coat wet inside.
2. Look at a duck: water rolls off its oily feathers.
3. Choose a coat with a waterproof outside so water rolls off.
4. Pour a cup of water over the coat. Check the inside.

If the inside is dry, the coat has kept that water out. If it is wet, try a different covering. The useful job is keeping water out; the coat does not need to look like a duck.

A grown-up animal can have young. Offspring is another word for an animal's young. The grown-ups who have them are their parents.

Baby names

Some baby animals have special names. Here are names you can match.

Some names fit more than one animal. A young cow, elephant, giraffe or whale can be called a calf. A young bear, lion, tiger or fox can be called a cub. If someone says “calf,” ask which animal they mean.

Hatching or being born

To hatch means to break out of an egg. All birds hatch from eggs. Most fish, amphibians and reptiles do, too. A chick uses a tiny hard tip on its beak to start breaking its shell. This tip is called an egg tooth.

Most mammals are born alive. They grow inside their mother until they come out. Puppies, foals and human babies begin life this way. Platypuses and echidnas are mammals that hatch from eggs.

Match, then sort

Start with these pairs: hen and chick, cow and calf, frog and tadpole, sheep and lamb, horse and foal.

First match each baby to its parent. Then ask how the baby started life. Chick and tadpole go in the hatched group. Calf, lamb and foal go in the born-alive group. That gives 2 hatched and 3 born-alive young.

A different baby name does not mean a different kind of animal. A tadpole is a frog's young, even though it looks different. Young grow and change: a puppy becomes a grown dog. A chick grows into a hen or a rooster.

A kitten can look like its mother without being an exact copy. Look for things they share, then look for differences.

Compare one feature at a time

Start with size. Then check the body covering, color, legs, ears and tail. Looking at the same feature on each animal helps you make a clear comparison.

Compare a lamb with its mother sheep.

Both have a similar face shape. The lamb is the same kind of animal as its mother, even though it is smaller and feeds differently.

Families have differences

Kittens from the same mother may have different colors and patterns. Puppies born together may differ in size. A brown dog and a white dog are still both dogs.

People have family likenesses, too. Brothers and sisters can share some features and differ in others. Being in one family does not mean looking exactly alike.

Growing changes a body

Most young animals grow bigger. Some change in other ways, too. A young deer, called a fawn, can have white spots that fade as it grows. A chick has soft, fluffy feathers called down. Stronger feathers grow as it gets older.

A tadpole looks very different from a frog. It starts with a tail, gills and no legs. As it grows, legs and lungs develop, and the tail shrinks. It stays a frog's young throughout these changes.

You can describe both likeness and difference in one sentence: “The lamb and its mother both have hooves, but the lamb is smaller.” That tells someone exactly what you noticed.

Many animal parents help their young until they can manage by themselves. Watch what a parent does, then ask which need it meets.

Feeding and warming

Mammal mothers make milk for their babies. Bird parents bring insects, worms or seeds to chicks in a nest. These actions give young animals food to grow.

Birds sit on eggs to keep them warm. An emperor penguin father holds an egg on his feet under a warm fold of skin. He keeps it there for about 2 months until it hatches.

Protecting and carrying

A mother bear stays near her cubs and drives danger away. A mother crocodile gently carries her babies in her mouth to the water.

A joey rides in its mother's pouch. A baby monkey holds its mother's fur. A cat carries a kitten by loose skin at the back of its neck. A seahorse father carries eggs in a pouch until the babies come out. Different parents carry young in different ways.

Signals and answers

A hungry chick cheeps and opens its beak. A parent answers by bringing food. Follow the steps: the chick calls, the parent brings food, and the chick eats.

A puppy can whine for help. Its mother may feed or comfort it. A human baby cries, and a grown-up checks what it needs. The grown-up may feed, hold or comfort the baby.

Some young learn by watching. Lion cubs watch their mother hunt and practice through play. Ducklings follow their mother toward water.

Growing without parent care

Not all young have a parent beside them. Most fish, many frogs and sea turtles leave their eggs. Baby sea turtles hatch on a beach and crawl toward the sea without a parent leading them. At first they use food stored from the egg. Later they find food themselves.

Animals without parent care often have many young at once. A frog may lay hundreds or thousands of eggs. A horse usually has 1 foal. Many young fish must manage alone; the foal has a mother to feed and protect it.