The pyramid of biomass in the sea is generally inverted because:

The correct answer is Option (1) → The biomass of fishes far exceeds than that of phytoplankton.

A pyramid of biomass shows the total dry weight of living organisms at each trophic level. It is usually upright, with the producers as the widest base. In the sea it is inverted.

(1) The biomass of fishes far exceeds than that of phytoplankton. — Correct. Phytoplankton are the producers at the base and their standing crop is small at any moment. The fishes at the top have a far larger biomass, so the base is narrower than the top.

(2) The biomass of phytoplankton far exceeds than that of zooplankton. — Incorrect. If the producers were larger than the next level, the pyramid would be upright. In the sea the small crop of phytoplankton supports a larger crop of zooplankton.

(3) The biomass of zooplankton far exceeds than that of fishes. — Incorrect. This compares two upper levels. It says nothing about the producers at the base, so it cannot make the whole pyramid inverted.

(4) The biomass of phytoplankton far exceeds than that of fishes. — Incorrect. This would give a broad base and a narrow top, which is an upright pyramid.

Note: A similar question was also asked in CUET (UG) 2026 on 24-05-2026 (Slot 2), 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.”