Ecological Pyramids

Option (A):
Step 1: In an aquatic ecosystem, the biomass pyramid is usually inverted. The three trophic levels are:
1. Phytoplankton (producers)
2. Zooplankton (primary consumers)
3. Small fishes (secondary consumers)
Step 2: It is inverted because the biomass of phytoplankton is less at any given time, yet they reproduce rapidly to support higher trophic levels.
OR
Option (B):
Step 1: In a pyramid of numbers with one large tree at the base, it supports many insects.
Step 2: These insects are eaten by fewer small birds, which are in turn consumed by even fewer big birds.
Step 3: This results in a spindle-shaped or inverted pyramid of numbers.