The 10% rule states that as energy is transferred from one trophic level to the next in an energy pyramid, only about 10% of the energy is passed on to the next level. The rest of the energy is lost as heat or used by the organism for respiration and other metabolic processes. This relates to the energy pyramid by illustrating how energy becomes less and less available as it moves up the trophic levels. This is why the producers or plants at the base of the pyramid have the most energy available, while top predators at the apex of the pyramid have the least amount of energy available.
