Sequence of a Marine Food Chain — UPSC Prelims PYQ 2014

Which one of the following is the correct sequence of a food chain?

Diatoms-Crustaceans-Herrings
Crustaceans-Diatoms-Herrings
Diatoms-Herrings-Crustaceans
Crustaceans-Herrings-Diatoms

Explanation

Option (a) is correct

The food chain starts with producers and ends with top consumers.
Phytoplankton are the primary producers in the oceans. They include:
- diatoms (unicellular algae),
- coccolithophores (unicellular, eukaryotic protist),
- Cyanobacteria (Bluegreen algae) — Synechococcus, Prochlorococcus, Nostoc, spirogyra, etc., and
- Dinoflagellates (flagellated protists).
Crustaceans form a large group of arthropods, including crabs, lobsters, shrimp, krill, etc.
Herrings are fish, and they eat crustaceans.

Diagram of marine food web illustrating feeding relationships among various ocean species. Color-coded layers represent trophic levels from phytoplankton (green and blue) at bottom to apex predator shark at top, with arrows indicating energy flow through species like copepods, anchovy, squid, tuna, and shark.