Approximately what percentage of energy is transferred from one trophic level to the next, and what happens to the rest?

• A. About 90%
• B. About 50%
• C. About 10% (often between 5-20%)
• D. About 1%

Answer: (C)

Energy moves through ecosystems in a stepwise, inefficient way. Only a small fraction of the energy at one trophic level becomes new biomass at the next level. This transfer is roughly 10%, and it can vary anywhere from about 5% to 20%.

The rest of the energy is lost mainly as heat through metabolic processes like respiration, movement, and maintaining body temperature. Some energy is also lost in waste or in parts of the organism that aren’t eaten or digested, ending up as detritus. Because so much energy is lost at each step, higher trophic levels receive far less energy, which is why food chains are typically short.