Which one of the following is the correct sequence of a food chain?
Answer & explanation
Answer: (a) Diatoms-Crustaceans-Herrings
A food chain starts with a producer and moves up through the animals that eat it. Diatoms are microscopic algae that make their own food, so they come first. Small crustaceans of the zooplankton graze on them, and herrings feed on these crustaceans.
- ✓ (a) Diatoms are producers, a type of phytoplankton. They are eaten by tiny crustacean zooplankton such as copepods. Herrings eat zooplankton, so the order is Diatoms → Crustaceans → Herrings.
- ✗ (b) This puts crustaceans before diatoms. Crustaceans are animals and cannot start a chain; diatoms make food from sunlight, so they are the base.
- ✗ (c) This makes crustaceans eat herrings. It is the other way round: herrings feed on small crustaceans.
- ✗ (d) This ends the chain with diatoms, the producers. Energy flows from producers to consumers, so diatoms must be at the start.
Remember · A food chain begins with a producer. In the sea the usual order is phytoplankton (e.g. diatoms), then zooplankton (e.g. copepod crustaceans), then small fish such as herring.
📘 Read it in NCERT: Class 8 Curiosity, Ch 2 (practise this chapter)
Sources
- NCERT Class 8 · Curiosity, Chapter 2 “They are rich in nutrients and serve as a food source for many aquatic animals. Some, like Spirulina, Chlorella, and Diatoms, are also used by humans as health supplements and medicines.”
- NOAA Fisheries – Copepods: Cows of the Sea ↗ “Tiny crustacean zooplankton called “copepods” are like cows of the sea, eating the phytoplankton and converting the sun’s energy into food for higher trophic levels in the food web.”
- NOAA Fisheries – Atlantic Herring species profile ↗ “Atlantic herring feed on zooplankton (tiny floating animals), krill, and fish larvae.”
- NOAA National Ocean Service – What is phytoplankton? ↗ “The two main classes of phytoplankton are dinoflagellates and diatoms.”
Question: UPSC Civil Services (Preliminary) 2014, General Studies Paper I. Explanation: Minimalist IAS, checked 25 Oct 2026 (how we verify). ·
