The pyramid of energy expresses the law, according to which the energy flow is gradually reduced and impaired when moving from link to link in the food chain. So, in the biocenosis of the lake green plants — the producers — create a biomass containing 295,3 kJ/cm2, the consumers of I order, consuming the biomass of plants, create a biomass containing 29,4 kJ/cm2; consumers of II order, using food consumers 1 order, create a biomass that contains at 5.46 kJ/cm2. The energy loss during the transition from consumers of I order to the consumers II order, if it is warm-blooded animals, increases. This is due to the fact that in these animals a lot of energy is spent not only to build their biomass, but also on the maintenance of a constant body temperature. The knowledge of energy losses in power circuits gives you the opportunity to assess how economically profitable to grow this or that animal, to cultivate a particular plant.