On average, what percent of energy is transferred from one trophic level to the next?

• A. About 10%
• B. About 50%
• C. About 90%
• D. About 1%

Answer: (A)

Energy transfer between trophic levels is inefficient because organisms use much of the energy they obtain for daily activities—respiration, movement, growth, and maintenance—and much is lost as heat or remains in indigestible matter. As a result, only a portion of the energy at one level becomes available to the next. On average, about 10 percent of the energy at one trophic level is passed to the next level. This makes energy pyramids slope downward quickly and helps explain why food chains are relatively short. For example, if producers have 1000 units of energy, roughly 100 units are transferred to herbivores, then about 10 units to carnivores, and so on.