Question
How do we classify living organisms into plants and animals? Further classify animals into vertebrates and invertebrates with examples of each group.
(CBSE Class 6 and Class 9 Science)
Solution — Step by Step
| Feature | Plants | Animals |
|---|---|---|
| Food | Make their own (autotrophs) via photosynthesis | Eat other organisms (heterotrophs) |
| Movement | Cannot move from place to place | Can move freely |
| Cell wall | Present (made of cellulose) | Absent |
| Growth | Grow throughout life | Grow till a certain age |
| Response | Slow response to stimuli | Fast response to stimuli |
| Group | Key features | Examples |
|---|---|---|
| Fish | Gills, fins, scales, cold-blooded | Rohu, shark |
| Amphibians | Live on land and water, moist skin | Frog, salamander |
| Reptiles | Dry scaly skin, cold-blooded | Snake, lizard, crocodile |
| Birds | Feathers, beak, warm-blooded, lay eggs | Crow, eagle, penguin |
| Mammals | Hair/fur, warm-blooded, feed milk to young | Human, cow, whale |
About 97% of all animal species are invertebrates:
| Group | Examples |
|---|---|
| Insects | Butterfly, ant, mosquito |
| Arachnids | Spider, scorpion |
| Molluscs | Snail, octopus |
| Worms | Earthworm, tapeworm |
| Crustaceans | Crab, prawn |
| Cnidarians | Jellyfish, coral |
Living Things Classification Tree
flowchart TD
A["Living Organisms"] --> B["Plants — make own food"]
A --> C["Animals — eat other organisms"]
C --> D["Vertebrates — have backbone"]
C --> E["Invertebrates — no backbone"]
D --> D1["Fish"]
D --> D2["Amphibians"]
D --> D3["Reptiles"]
D --> D4["Birds"]
D --> D5["Mammals"]
E --> E1["Insects"]
E --> E2["Arachnids"]
E --> E3["Molluscs"]
E --> E4["Worms"]
E --> E5["Crustaceans"]Why This Works
Classification groups organisms based on shared features. This makes it easier to study millions of species by putting similar ones together. The most fundamental division is how an organism gets food (plant vs animal). Among animals, the presence or absence of a backbone (vertebral column) is a major structural difference.
Scientists use classification to identify relationships between organisms and understand how they evolved.
Common Mistake
Whales and bats confuse many students. A whale lives in water but is a mammal (not a fish) — it breathes air, is warm-blooded, and feeds milk. A bat flies but is a mammal (not a bird) — it has fur, not feathers, and feeds milk to its young. Classification is based on body features, not habitat or mode of movement.