The pyramid of numbers is based on what measure?

• A. Biomass at each trophic level
• B. Number of species
• C. Number of individual organisms at each trophic level
• D. Energy at each trophic level

Answer: (C)

The pyramid of numbers shows how many individual organisms occupy each trophic level in an ecosystem. It’s based on counting the actual organisms at each level, not their size or how much energy they contain. That’s why it differs from the pyramid of biomass (which uses mass) and the pyramid of energy (which tracks energy flow). It also isn’t about how many species exist at each level—that would be related to biodiversity, not the count of individuals. Because this diagram counts individuals, its shape can sometimes be inverted if a small number of producers support large numbers of consumers, but the fundamental idea remains counting the number of organisms at each level.