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UPSC Prelims 1982 · Environment · Species Watch
Plankton refers to
- (a) A kind of fish
- (b) A submerged platform in waters
- (c) Drifting of organisms in a body of water
- (d) A kind of animal living under water
Show the answer and explanation
Answer: (c) Drifting of organisms in a body of water
Plankton are organisms that drift with the currents — phytoplankton (plants) and zooplankton (animals).
The idea
Sea life is sorted by how it moves, not by what it is. Plankton drift with the current. Nekton swim where they choose. Benthos live on the bottom.
Plankton (drifters): algae, copepods, jellyfish → Nekton (swimmers): fish, squid, whales → Benthos (bottom-dwellers): crabs, starfish, corals
Why the others are wrong
(a) Plankton is not one kind of fish.
(d) Plankton includes plants and microbes, not only animals, and the key idea is drifting.
Also know
The word comes from the Greek for “wanderer”. Size is not the test: a large jellyfish is plankton because it cannot swim against a current.
🔒 Plankton = drifters · nekton = active swimmers · benthos = bottom-dwellers.