READ: Energy Flow in Ecosystems

Energy flows through an ecosystem in only one direction. Energy is passed from organisms at one trophic level or energy level to organisms in the next trophic level. Which organisms do you think are at the first trophic level (Figure below)?

Most of the energy at a trophic level – about 90% – is used at that trophic level. Organisms need it for growth, locomotion, heating themselves, and reproduction. So animals at the second trophic level have only about 10% as much energy available to them as do organisms at the first trophic level. Animals at the third level have only 10% as much available to them as those at the second level.