Exercises: The energy pyramid

Look at the energy pyramid in the diagram. Identify which trophic level occupies each floor and calculate the missing value, assuming that in every transfer only 10% of the energy passes to the next level.

In an ecosystem, the carnivores receive 500 kJ of energy per year. If only 10% of the energy passes to the next level in each transfer, calculate how much energy the producers had to capture to support those carnivores (producers → herbivores → carnivores). Also explain why food chains rarely have more than four or five levels.