Approximately what percentage of energy is transferred from one trophic level to the next?

• A. 50% passes
• B. 90% passes
• C. Only 10% of energy is passed to the next trophic level
• D. 100% passes

Answer: (C)

Energy transfer between trophic levels is inherently inefficient because organisms must use energy for metabolism, movement, growth, and maintenance, with much of the consumed energy released as heat or lost in waste. Only a small portion becomes new biomass that the next level can feed on, so the typical transfer is around 10%. This pattern, known as the 10% rule, creates the characteristic steep drop in energy as you move up trophic levels in an ecosystem’s energy pyramid. In real systems, the exact figure can vary, often roughly 5–20%, but 10% is the classic, widely used approximation. The larger percentages would imply far more energy being retained at each step than is realistically available after accounting for heat loss and inefficiencies.