Which pyramid is based on the number of individual organisms at each trophic level?

• A. Pyramid of biomass
• B. Pyramid of numbers
• C. Energy pyramid
• D. Pyramid of productivity

Answer: (B)

Ecological pyramids can be built using different criteria, and this question focuses on counting organisms. The pyramid of numbers shows how many individual organisms exist at each trophic level—from producers up through top predators. That’s why it’s the best choice here: it directly reflects the count of organisms at each step of the food chain, not their total mass or the energy flowing between levels.

Keep in mind that the other pyramids measure different things: biomass sums the total mass of all organisms at each level, energy pyramids track how much energy is transferred from one level to the next (usually decreasing), and productivity pyramids look at the rate of new biomass production over time. These describe aspects other than simply how many individuals are present at each level.