Animals
Primary 6 · English
Animals
Lesson 1 of 4
20 min
Let's begin
Byiringiro and Keza are sorting animal picture cards for a class game. Keza puts the bat with the birds, because it flies. Byiringiro moves it next to the cow and the goat.
"A bat is not a bird!" he says. "Yes it is. It has wings!" says Keza. Who is right? Today you will learn how scientists sort animals, and you will be able to settle the argument yourself.
There are millions of kinds of animals. To study them, scientists look for things that animals have in common, and they use these to put the animals into groups. This is called classification.
The first question is simple: does it have a backbone? A backbone, or spine, is a row of small bones called vertebrae that runs down the middle of the back. Animals with a backbone are called vertebrates; the word comes from vertebrae. Animals without a backbone are called invertebrates. Insects, spiders, snails, worms and jellyfish are all invertebrates.
Vertebrates are sorted again into five classes: fish, amphibians, reptiles, birds and mammals.
| Class | Body covering | Warm or cold? | Babies | Examples in Rwanda |
|---|---|---|---|---|
| Mammals | hair or fur | warm-blooded | most are born alive and drink their mother's milk | cows, goats, mountain gorillas, bats, people |
| Birds | feathers, with a beak and wings | warm-blooded | hatch from eggs with hard shells | grey crowned cranes, chickens, sunbirds |
| Reptiles | dry scales | cold-blooded | most hatch from eggs with leathery shells, laid on land | Nile crocodiles, chameleons, snakes, lizards |
| Amphibians | smooth, moist skin | cold-blooded | hatch from jelly-covered eggs in water, as tadpoles | frogs, toads |
| Fish | wet scales and fins; they breathe with gills | cold-blooded | most hatch from eggs laid in water | tilapia, catfish, isambaza from Lake Kivu |
A warm-blooded animal keeps its body at the same warmth, whether the day is hot or cold. Mammals and birds are warm-blooded. A cold-blooded animal takes its warmth from its surroundings. That is why a lizard lies on a sunny rock in the morning before it can run fast. Reptiles, amphibians and fish are cold-blooded.
Herbivores eat only plants: cows, zebras and giraffes. Carnivores eat only meat: lions, leopards and crocodiles. Omnivores eat both plants and meat: people, chimpanzees and chickens.
Careful! Never sort by one thing only. A bat flies, but it has fur and feeds its babies on milk, so it is a mammal, not a bird. A spider looks like an insect, but it has eight legs, not six, so it is not an insect. And a snake is a reptile, not an amphibian, because its skin is dry and scaly.
When you classify an animal, you ask questions. Each question word asks for a different kind of answer.
| Question | Answer |
|---|---|
| How many legs does a spider have? | It has eight legs. |
| What kind of animal is a chameleon? | It is a reptile. |
| How big is a mountain gorilla? | A grown male is about as tall as a man and more than twice as heavy. |
| Does a frog have a backbone? | Yes, it does. It is a vertebrate. |
| Which class does the crowned crane belong to? | It belongs to the bird class. |
Useful sentence patterns for classifying:
Worked example
classify the bat.
Step 1 Does it have a backbone? Yes, so it is a vertebrate.
Step 2 What covers its body? Fur, which points to the mammals.
Step 3 How are its babies fed? On their mother's milk. That settles it.
Answer: A bat is a mammal because it has fur and feeds its young on milk, even though it can fly. So Byiringiro was right.
Tip
Backbone first, then the skin
Ask two questions, in order. Does it have a backbone? If not, it is an invertebrate. If it does, look at its skin: hair means mammal, feathers mean bird, dry scales mean reptile, moist skin means amphibian, and wet scales with fins mean fish. The skin tells the truth even when the wings try to trick you.
Answer each one, then check yourself.
A chicken has feathers and lays eggs with hard shells. Which class does it belong to?
Answer: the bird class. Feathers are the clue: only birds have them.
Is a butterfly a vertebrate or an invertebrate?
Answer: an invertebrate. It has no backbone. It is an insect, with six legs.
How many legs does an insect have? Answer in a full sentence.
Answer: An insect has six legs.
A leopard eats only meat. Is it a herbivore, a carnivore or an omnivore?
Answer: a carnivore. Carnivores eat only meat.
Write a sentence that explains why a frog is an amphibian.
Answer: for example, “A frog is an amphibian because it has smooth, moist skin and it starts its life in water as a tadpole.”
What you learned today
Sources and credits
This lesson adapts CC BY-SA material and is shared under CC BY-SA 4.0.
Quick check
A chameleon has dry, scaly skin and is cold-blooded. Which class does it belong to?
