The pyramid of biomass in sea is generally inverted because:

The correct answer is Option (1) → Biomass of fishes far exceeds that of phytoplankton

A pyramid of biomass shows the total mass of living matter at each trophic level at a given time. In the sea the producers are tiny phytoplankton, which grow and reproduce very fast. At any moment their mass is small, but the fishes that feed on them live long and build up a larger mass. So the bottom bar is smaller than the one above it, and the pyramid is inverted. A pyramid of energy is different. It is always upright, because some energy is lost as heat at each step.

(1) Biomass of fishes far exceeds that of phytoplankton — Correct. This is the reason for the inverted shape.

(2) Biomass of fish does not depend on phytoplankton — Incorrect. Fishes depend on phytoplankton for food, directly or through other animals.

(3) Biomass of fish depends directly on sunlight — Incorrect. Only the producers use sunlight. Fishes get their energy from food.

(4) Biomass of fish is more dependent on gravity — Incorrect.

Note: A similar question was also asked in CUET (UG) 2026 on 21-05-2026 (Slot 1), and in CUET (UG) 2022 on 16-07-2022 (Slot 1).

NCERT Extract:
Ecological Pyramids – “… In most ecosystems, all the pyramids, of number, of energy and biomass are upright, i.e., producers are more in number and biomass than the herbivores, and herbivores are more in number and biomass than the carnivores.”
Ecological Pyramids – “… The pyramid of biomass in sea is generally inverted because the biomass of fishes far exceeds that of phytoplankton.”