Animal Life — Class 3 Science (Samacheer Kalvi)
TN State Board (Samacheer Kalvi) Class 3 Science. Habitats, food habits, breathing and adaptations.
1. Grouping animals by where they live
The place an animal lives is its habitat.
| Group | Where it lives | Examples |
|---|---|---|
| Terrestrial | On land | Lion, elephant, cow, camel |
| Aquatic | In water | Fish, dolphin, octopus, shark |
| Amphibian | Both land and water | Frog, toad |
| Aerial | Mostly in the air | Eagle, parrot, sparrow |
Living in water does not make an animal a fish. A whale lives in the sea but is a mammal: it breathes air through lungs and must come to the surface, it gives birth to live young rather than laying eggs, and it feeds them on milk. A fish does none of these things.
2. Grouping animals by what they eat
| Group | What it eats | Examples |
|---|---|---|
| Herbivore | Only plants | Cow, goat, deer, elephant |
| Carnivore | Only other animals | Lion, tiger, eagle, shark |
| Omnivore | Both plants and animals | Crow, bear, human |
Teeth are a clue. Herbivores have broad flat teeth for grinding leaves, while carnivores have long pointed teeth for tearing meat.
3. How animals breathe
Every animal needs oxygen, but not every animal takes it in the same way.
- Lungs: most land animals, including humans, dogs and elephants. Whales and dolphins too.
- Gills: most water animals, such as fish, crabs and prawns. Gills take oxygen dissolved in the water.
- Skin as well as lungs: an adult frog can take in oxygen through its moist skin.
- Tiny air tubes: insects breathe through small tubes running into the body.
4. Adaptations
An adaptation is a body feature that suits an animal to its home.
Fish have gills for breathing in water, fins for steering and a smooth streamlined body that slips through water easily.
Camel has wide padded feet that do not sink into sand, long eyelashes that keep sand out of its eyes, and a hump. The hump stores fat, not water. That fat is a store of energy for days when there is nothing to eat.
Birds have wings, feathers, and bones that are hollow rather than solid, which keeps them light enough to fly.
Not every bird flies, though. An ostrich is far too heavy and runs instead, very fast. A penguin uses its wings as flippers to swim. A kiwi has wings so small they are almost invisible.
5. Special features
Some animals have features that stand out.
- Shells: a turtle and a snail both carry hard shells for protection.
- Camouflage: a chameleon changes colour to match its surroundings, so predators pass it by.
- Skin breathing: a frog begins life with gills as a tadpole and later uses lungs and skin.
6. Worked examples
Example 1. Is a whale a fish? Give two reasons.
No, it is a mammal. It breathes air through lungs rather than gills, and it gives birth to live young and feeds them milk.
Example 2. A camel crosses a desert for several days without food. What is it using?
The fat stored in its hump, which the body breaks down for energy. The hump does not store water.
Example 3. Name one bird that cannot fly and say what it does instead.
An ostrich cannot fly and runs very fast instead. A penguin cannot fly either and swims using its wings as flippers.
Example 4. A cow and a lion are both mammals. How would their teeth differ, and why?
The cow has broad flat teeth for grinding plants, because it is a herbivore. The lion has long pointed teeth for tearing meat, because it is a carnivore.
7. Practice
- Give two examples each of a terrestrial, an aquatic and an aerial animal.
- What is an amphibian? Give one example.
- Sort these by food habit: goat, tiger, crow.
- Which organ do fish use for breathing, and where does the oxygen come from?
- Name three adaptations of a camel to desert life.
- Why are birds' bones hollow?
- Name an animal that uses camouflage and say how it helps.
8. Answers
- Terrestrial: lion, cow. Aquatic: fish, dolphin. Aerial: eagle, sparrow.
- An animal that lives both on land and in water, such as a frog.
- Goat is a herbivore, tiger a carnivore, crow an omnivore.
- Gills, which take in oxygen dissolved in the water.
- Wide padded feet, long eyelashes, and a hump storing fat for energy.
- Hollow bones are lighter, which makes flight possible.
- The chameleon, which changes colour to match its surroundings so predators do not spot it.
9. Summary
- Habitat groups are terrestrial, aquatic, amphibian and aerial.
- A whale lives in water but is a mammal: lungs, live young, milk.
- Food habit groups are herbivore, carnivore and omnivore, and teeth give the clue.
- Lungs, gills, moist skin and air tubes are four different ways of taking in oxygen.
- An adaptation is a body feature suited to the habitat.
- A camel's hump stores fat, not water.
- Not all birds fly: the ostrich runs and the penguin swims.
