Food chain and food web reflect the

Food chain and food web reflect the complex nutrition relationship between biological species and species. From the perspective of energy, because the energy flow of the ecosystem is unidirectional, the energy through each trophic level will be gradually reduced, because: (1) consumers of each trophic level cannot fully absorb the biomass of the previous trophic level, and some of the excrement or biological residues will be decomposed; (2) the assimilation rate of each trophic level is also not 100%; and (3) the organisms of each trophic level Some energy must be expended to sustain life. To maintain the normal function of ecosystem, there must be continuous energy input. As the energy is gradually reduced through the trophic level, if the energy flow through each trophic level becomes a pyramid from low to high, it is called the energy pyramid