Chapter 9 of 10

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Tamil Nadu (TNBSE)Class 3 Science★ 5-6 marks in TN Class 3 Term 3 exams — habitat classification, adaptations, food habits, and short written answers

Animal Life

Samacheer Kalvi (TN State Board) Class 3 Science — Chapter 9, Animal Life. Classification and life processes in animals. Study notes, key concepts, worked examples, practice questions and quick revision for exam preparation.

⏱ 10 min readeasy-to-medium difficulty✓ Free · NCERT-aligned

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By the end of this chapter you'll be able to…

1Classify animals by habitat: land animals (terrestrial), water animals (aquatic), animals that live both on land and water (amphibians), and animals that fly (aerial)
2Give 3 examples of each habitat type
3Explain 3 adaptations: fish have gills (breathe in water), camel has hump and long eyelashes (desert survival), bird has wings and hollow bones (flight)
4Classify animals by food habits: herbivores, carnivores, omnivores — with examples
5Identify special features: animals that breathe through skin (frog), animals that have shells (turtle, snail), and animals with camouflage (chameleon)

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Why this chapter matters

Animals live everywhere — in forests, oceans, deserts, and even in our homes. This chapter teaches children to classify animals by habitat (land, water, air) and understand how each animal's body is adapted to where it lives. A fish has gills to breathe underwater; a camel has a hump to store fat in the desert; a bird has hollow bones to fly. This is evolution and adaptation made simple for a 9-year-old — and it plants the seed for understanding biodiversity and why we must protect different habitats.

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Animal Life — Class 3 Science (Samacheer Kalvi)

TN State Board (Samacheer Kalvi) Class 3 Science, Chapter 9. Classification and life processes in animals.

1. About this chapter

This chapter covers Animal Life as part of the Class 3 Samacheer Kalvi Science curriculum. It deals with classification and life processes in animals and builds conceptual understanding essential for the TN School Term Exam.

By the end of this chapter, students will be able to:

Classify animals by diet and habitat
Describe basic life processes in animals

2. Key concepts

Concept 1: Classify animals by diet and habitat.
Concept 2: Describe basic life processes in animals.

3. Important terms and formulas

Term / Formula	Description
Classify animals by diet…	Classify animals by diet and habitat
Describe basic life processes…	Describe basic life processes in animals

4. Worked examples

Example 1. Applying a key concept from this chapter.

Solution: Identify the relevant principle → apply the formula or rule → state the answer with correct units.

Example 2. A typical exam-style question on animal life.

Solution: Break the problem into steps, use the appropriate formula and verify the answer.

5. Common mistakes

Mistake: Skipping units or forgetting to state them. Fix: Always write units alongside every quantity and answer.
Mistake: Confusing similar terms or concepts in this chapter. Fix: Make a comparison table of the terms during revision.

6. Practice (exam-style)

Define the main term or principle covered in Chapter 9.
Give two real-life examples related to animal life.
Solve a short numerical or descriptive question from this chapter.
State one important formula and explain each symbol.

7. Answer key (hints)

Refer to section 2 (Key concepts) above for the definition.
Examples should be drawn from daily experience and local context.
Apply the formula from section 3, show all steps clearly.
Formula with units — refer to the textbook glossary for symbol meanings.

8. Quick revision

Class 3 Science — Chapter 9: Animal Life.
Core idea: Classification and life processes in animals.
Key outcomes: Classify animals by diet and habitat; Describe basic life processes in animals.
Always revise diagrams / tables from the Samacheer Kalvi textbook before the exam.

Key formulas & results

Everything you need to memorise, in one card. Screenshot this for revision.

Animals by habitat

Land animals (terrestrial) → live on land. Examples: lion, tiger, elephant, cow, dog, camel. Water animals (aquatic) → live in water. Examples: fish, whale, dolphin, octopus, shark. Amphibians → live both on land and in water. Examples: frog, toad, salamander. Aerial animals → fly in the air. Examples: birds (crow, eagle, sparrow), bats, flying insects (butterfly, dragonfly).

Frogs are amphibians — they are born in water (as tadpoles with gills), then grow legs, develop lungs, and can live on land as adults. But they always need to stay near water because their skin must stay moist to breathe.

Animal adaptations

Fish → gills to breathe underwater, fins to swim, streamlined body. Camel → hump stores fat (not water!), long eyelashes protect from sand, wide padded feet for walking on sand. Bird → wings to fly, hollow bones (lightweight), beak instead of teeth. Chameleon → changes colour to match surroundings (camouflage). Turtle → hard shell to protect from predators.

Adaptations develop over millions of years through evolution. A polar bear's white fur is not a coincidence — bears with whiter fur survived better in snow, so over generations, polar bears became white.

Animal breathing organs

Land animals (most) → lungs (humans, dogs, elephants, lions). Water animals (most) → gills (fish, crabs, prawns). Amphibians → gills as young, lungs + skin as adults. Insects → tiny air tubes called tracheae (spiracles on body sides). Earthworm → breathes through moist skin.

Whales and dolphins are mammals, not fish — they breathe air through lungs and must surface to breathe. They have a blowhole on top of their head for this.

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Common mistakes & fixes

These are the exact errors that cost students marks in board exams. Read them once, save yourself the trouble.

WATCH OUT

✗ Calling a whale a fish because it lives in water

✓ Whales are mammals. They: breathe air through lungs (not gills), give birth to live young (not eggs), feed babies milk, and are warm-blooded. These are all mammal characteristics. A fish has gills, lays eggs, and is cold-blooded.

WATCH OUT

✗ Thinking a camel's hump stores water

✓ The hump stores FAT, not water. The camel uses this stored fat for energy when food and water are scarce. The camel can survive long periods without water because of other adaptations — it can drink 100+ litres at once, its urine is very concentrated (saves water), and it can tolerate a body temperature rise that would kill most animals.

WATCH OUT

✗ Thinking all birds can fly

✓ Some birds cannot fly: ostrich (largest bird, runs fast instead), penguin (uses wings as flippers to swim), kiwi (New Zealand's national bird, no wings). These are called flightless birds.

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