Britannica
Sources used in this answer
Why is less energy available at higher trophic levels?
Created from Britannica articles
using AI.
AI can make mistakes, so verify using Britannica articles.
Biosphere
Earth's environment includes the atmosphere, the hydrosphere, the lithosphere, and the biosphere.
Energy availability decreases at higher trophic levels primarily due to the inefficiency of energy transfer between organisms in a food chain.12
On average, only about 10 percent of the energy stored in one trophic level is converted into biomass at the next level. This loss occurs for several reasons:1
- Metabolic Heat Loss: Organisms expend a significant portion of the energy they ingest—often 80 to 90 percent—on metabolic processes such as digestion, movement, and maintaining body temperature, which is released into the environment as heat.23
- Incomplete Consumption: Much of the plant or animal tissue produced at lower levels is never consumed by the next level. For instance, in terrestrial ecosystems, herbivores consume less than 10 percent of available plant tissue.1
- Detritus Pathway: Energy that is not eaten by consumers or assimilated into biomass is diverted into the detritus food chain, where it is processed by decomposers rather than moving directly up the primary food chain.1
Consequently, the higher an organism is on the trophic pyramid, the less energy is available to support its population.2