Exercise Solutions Available
Step-by-step answers for all textbook questions in this chapter
Quick Summary
The animal kingdom is classified into invertebrates (no backbone) and vertebrates (with backbone). This chapter covers the features and examples of major phyla and vertebrate classes. Classification questions and tabular comparisons are common in board exams.
Key Definitions
- Invertebrates: Animals without a backbone. About 95% of all animals.
- Vertebrates: Animals with a backbone (vertebral column). Belong to phylum Chordata.
- Bilateral Symmetry: Body can be divided into equal halves only along one plane.
- Radial Symmetry: Body can be divided into equal halves along any plane through the centre.
- Coelom: Fluid-filled body cavity between body wall and gut.
- Notochord: A rod-like structure that provides support — present in chordates.
- Cold-blooded: Body temperature changes with environment (ectothermic). Example: fish, frogs.
- Warm-blooded: Maintain constant body temperature (endothermic). Example: birds, mammals.
Major Invertebrate Phyla
| Phylum | Key Features | Examples |
|---|---|---|
| Porifera | Pores in body; no tissues | Sycon (sponge) |
| Coelenterata | Two-layered body; stinging cells | Hydra, jellyfish, coral |
| Platyhelminthes | Flatworms; no coelom | Tapeworm, Planaria, Liver fluke |
| Nematoda | Roundworms; pseudocoelom | Ascaris, Wuchereria |
| Annelida | Segmented; true coelom | Earthworm, leech |
| Arthropoda | Jointed legs; exoskeleton; largest phylum | Cockroach, crab, butterfly |
| Mollusca | Soft body; shell; mantle | Snail, octopus, squid |
| Echinodermata | Spiny skin; water vascular system | Starfish, sea urchin |
Vertebrate Classes
| Class | Features | Examples |
|---|---|---|
| Pisces | Aquatic; gills; scales; cold-blooded | Rohu, shark, seahorse |
| Amphibia | Land and water; moist skin; gills (larva), lungs (adult) | Frog, toad, salamander |
| Reptilia | Dry scaly skin; cold-blooded; lay eggs | Lizard, snake, crocodile, turtle |
| Aves | Wings; feathers; warm-blooded; hollow bones | Pigeon, sparrow, penguin |
| Mammalia | Mammary glands; hair; warm-blooded; viviparous (mostly) | Human, whale, bat, platypus |
Important Questions
One Mark
- Name the largest phylum in the animal kingdom.
- Which class of vertebrates has hollow bones?
- Define the term 'coelom'.
- Give one example of an echinoderm.
- Are birds warm-blooded or cold-blooded?
Short Answer (3 marks)
- Distinguish between cold-blooded and warm-blooded animals with examples.
- What are the features of phylum Arthropoda? Why is it considered the most successful phylum?
- Write any three differences between Amphibia and Reptilia.
Long Answer (5 marks)
- Describe the classification of vertebrates (5 classes) with two features and two examples each.
- Explain the major invertebrate phyla from Porifera to Echinodermata with features and examples.
Common Mistakes
- Confusing Platyhelminthes (flatworms) with Nematoda (roundworms) — both are worms but in different phyla.
- Stating that all mammals give birth to live young — platypus and echidna are egg-laying mammals.
- Forgetting that Arthropoda is the largest phylum (not vertebrates or any other group).
Revision Checklist
- [ ] Know 8 invertebrate phyla with features and examples
- [ ] Know 5 vertebrate classes with features and examples
- [ ] Distinguish cold-blooded vs warm-blooded with examples
- [ ] Know the unique features of each vertebrate class
- [ ] Can give examples from each classification group
Frequently Asked Questions
Animals are classified based on: body symmetry (radial or bilateral), presence/absence of coelom (body cavity), notochord, backbone (vertebrates vs invertebrates), nature of body covering, and reproductive methods.