All courses › Biology 1 › Energy in the food chain

Energy in the food chain

The producers bind solar energy in organic matter. When a consumer eats, only about 10 percent of the energy passes on to the next trophic level. The rest is used in cellular respiration and lost as heat. There is therefore less energy, and usually fewer animals, at each step. After two steps about 1 percent is left. Matter such as carbon and nitrogen, on the other hand, cycles. Energy does not. It must keep being supplied from the Sun.

En+1≈0.1 EnE_{n+1} \approx 0.1\, E_nabout 10 percent passed on

Symbols

EEenergy at the levelkJ
0.10.1the share passed on

Example

The producers have 100 000100\,000 kJ.

The herbivores get 100 000⋅0.1=10 000100\,000 \cdot 0.1 = 10\,000 kJ, and the carnivores 10 000⋅0.1=100010\,000 \cdot 0.1 = 1000 kJ.

Ten percent is a rule of thumb. Some chains transfer more, some less.
Practise ecology for free →

← Hardy-Weinberg · Capture and recapture →

Part of Biology 1: Ecology.