EVERYDAY SCIENCE

Detailed explanation-1: -On average, only about 10% of the energy stored as biomass in one trophic level-e.g., primary producers-gets stored as biomass in the next trophic level-e.g., primary consumers. Put another way, net productivity usually drops by a factor of ten from one trophic level to the next.

Detailed explanation-2: -On average, only about 10 percent of energy stored as biomass in a trophic level is passed from one level to the next. This is known as “the 10 percent rule” and it limits the number of trophic levels an ecosystem can support.

Detailed explanation-3: -As producers are consumed, roughly 10% of the energy at the producer level is passed on to the next level (primary consumers). The other 90% is used for life processes, such as photosynthesis, respiration, reproduction, digestion; and ultimately transformed into heat energy before the organism is ever consumed.

Detailed explanation-4: -Energy decreases as it moves up trophic levels because energy is lost as metabolic heat when the organisms from one trophic level are consumed by organisms from the next level.

Detailed explanation-5: -Only a fraction of the energy available at one trophic level is transferred to the next trophic level. The rule of thumb is 10%, but this is very approximate. Typically the numbers and biomass of organisms decrease as one ascends the food chain.