S2.2.2 Chapter 2
Grouping animals
Is a whale a fish?
Your guess
Pick one before you read on. It is fine to be wrong.
By the end you can
- Group animals into mammals, birds, fish, reptiles and amphibians
- Tell an insect from a spider by counting legs and body parts
There are millions of kinds of animals. We sort them into groups. Animals in one group share signs. Here are five groups.
A mammal has hair or fur. Mothers feed their young on milk. Most mammals give birth to live young. A goat, a bat and a whale are mammals. So are you.
A bird has feathers and a beak. It lays eggs with hard shells. A hen, an owl and a penguin are birds.
A fish lives in water and breathes with gills. It has fins. Most fish have scales.
A reptile has dry skin with scales. Most reptiles lay eggs on land. Snakes, lizards, crocodiles and tortoises are reptiles.
An amphibian has damp skin with no scales. Its young live in water and breathe with gills. Frogs and toads are amphibians. A young frog is a tadpole. Adults often live on land.
See it three ways
As a picture
In words
Each group has its own kind of covering. Look at the covering first. Then ask how it breathes and how it has young.
Some animals fool us. A bat flies, but it has fur and feeds its young milk. So a bat is a mammal. A penguin cannot fly, but it has feathers and lays eggs. So a penguin is a bird.
A wrong idea many people have
A whale lives in the sea, so it is a fish.
Why it feels right: A whale swims, lives in water and looks like a fish.
The test that breaks it: Ask two questions about any animal. Does it breathe air? Does it feed its young milk? A whale does both. It comes up to breathe, and its calf drinks milk. A fish breathes with gills, and no fish makes milk.
What is true: A whale is a mammal. So is a dolphin. Living in the sea does not make an animal a fish.
Small animals have groups too. An insect has six legs. Its body has three parts. They are the head, middle and back. Most insects have feelers on the head. Many have wings. Ants, flies and beetles are insects.
Draw it first
Draw an insect and a spider
1 Draw three round parts in a line and two feelers. Write insect and 3 parts.
2 Draw six legs on the middle part. Write 6 legs.
3 Draw a spider with two parts and eight legs. Write spider, 2 parts and 8 legs.
A spider is not an insect. It has eight legs and two body parts. It has no feelers and no wings.
Try it
Sort animals into five boxes
You need: paper and a pencil, or a stick and bare ground, pictures of animals in a book, or animals you know.
Be safe: Look at wild animals from far away. Never touch them. Wash your hands after you touch any animal.
- Draw five boxes. Write mammal, bird, fish, reptile and amphibian.
- Choose ten animals. Pick ones you know, or ones in a book.
- For each one, ask: what covers its body? How does it breathe?
- Write its name in the right box.
- Which animals were hard to place? Ask the two questions again.
What you will see: Each animal goes in one box. A bat goes with the mammals. A penguin goes with the birds. A whale goes with the mammals.
Key words
- mammal
- an animal with hair or fur that feeds its young on milk.
- reptile
- an animal with dry, scaly skin that mostly lays eggs on land.
- amphibian
- an animal with damp skin whose young live in water.
- insect
- an animal with six legs and three body parts.
Back to your guess
The answer is B: No, a whale is a mammal.
A whale is a mammal. It breathes air and feeds its young on milk. A fish breathes with gills, and no fish makes milk.
Check yourself
Try each one before you look. A wrong answer tells you where to go next.
Which of these animals is a mammal?
See the answer
A bat
A bat has fur and feeds its young on milk. It is a mammal, not a bird.
- If you chose A: An owl has feathers and lays eggs. It is a bird. A bat also flies, but it has fur and milk.
- If you chose B: A frog has smooth, damp skin. Its young live in water. It is an amphibian.
A dolphin lives in the sea. Which group is it in?
See the answer
Mammal
A dolphin breathes air and feeds its young milk. So it is a mammal.
- If you chose A: A dolphin breathes air and feeds its young milk. A fish breathes with gills and makes no milk.
- If you chose B: An amphibian has damp skin and its young breathe with gills. A dolphin does not.
- If you chose C: A reptile has dry scales. A dolphin has smooth skin and feeds its young milk.
How many legs and body parts does an insect have?
See the answer
6 legs and 3 parts
An insect has six legs and a body in three parts.
- If you chose B: That is a spider. A spider is not an insect.
- If you chose C: An insect has 3 body parts. Count the head, the middle and the back part.
Kofi finds 3 ants and 1 spider on a wall. How many legs are there in all?
See the answer
26
Each ant has 6 legs, so 3 ants have 18 legs. The spider has 8 legs. 18 and 8 make 26.
From an earlier chapter
A dead leaf is on the ground. Which group is it in?
Sort these animals: crocodile, hen, trout, frog, goat. Write the group of each.
See the answer
Crocodile: reptile. Hen: bird. Trout: fish. Frog: amphibian. Goat: mammal.
A crocodile has dry scales. A hen has feathers. A trout has gills and fins. A frog has damp skin. A goat has hair.
A tortoise has dry skin and a hard shell. It lays eggs on land. Which group is it in?
See the answer
Reptile
A reptile has dry, scaly skin. It mostly lays eggs on land. A tortoise does both.
- If you chose A: An amphibian has damp skin, and its young live in water. A tortoise has dry skin.
- If you chose C: Birds lay eggs too. But a bird has feathers. A tortoise has none. It has dry, scaly skin.
A penguin cannot fly. Which group is it in?
See the answer
Bird
A penguin has feathers and lays eggs. Some birds cannot fly, and it is one of them.
- If you chose B: A penguin swims, but it has feathers and breathes air. A fish has gills and fins.
- If you chose C: Not flying does not make a mammal. A mammal has fur and milk. A penguin has feathers.
Hana thinks a spider is an insect, because it is small. What should she check?
See the answer
Its legs and body parts.
A spider has 8 legs and 2 body parts. An insect has 6 legs and 3 body parts.
- If you chose A: Small animals can be spiders, snails or woodlice. Size does not make an insect.
- If you chose B: Many spiders hunt without a web. Count its legs and body parts instead.
Keep it
Copy this into your exercise book.
Mammals have fur and feed milk to young. Birds have feathers. Fish have gills and fins. Reptiles have dry scales. Amphibians have damp skin. An insect has 6 legs and 3 parts. A spider has 8 legs and 2 parts.
Draw: Draw an insect with three parts and six legs. Draw a spider with two parts and eight legs. Label each.