trophic pyramid

The basic structure of interaction in all biological communities characterized by the manner in which food energy is passed from one trophic level to the next along the food chain. The base of the pyramid is composed of species called autotrophs, the primary producers of the ecosystem. All other organisms in the ecosystem are consumers called heterotrophs, which either directly or indirectly depend on the primary producers for food energy.

Citation: 
"trophic pyramid". Encyclopædia Britannica. Encyclopædia Britannica Online. Encyclopædia Britannica Inc., 2015. Web. 13 Apr. 2015
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trophic pyramid [image]

Figure 5: A simple trophic pyramid demonstrates the loss of energy (kilo calories, or biomass) from one tropic level to the next. Depicted as a pyramid, we can see that the primary producers or photosynthesizing autotrophs, make up the base of most food webs. As energy is transferred up the pyramid toward the top carnivores, approximately 90% is lost at each level, and only 10% is converted into biomass of the next higher trophic level.[fn][[nid:1284]][/fn]
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trophic pyramid [cite]

Adapted by Philip Nahlik, Chris Wolff from Biological Science by Freeman, 2008 Pearson Education, Inc.