Energy flows from one body to another to maintain equilibrium in the universe. In a food chain too, energy flows from one trophic level to another.

First herbivores animals feed on plants or the producers; energy is transferred from the plants to the herbivores. Herbivores are eaten up by carnivores, which in turn are fed upon by Omnivores. These plant and animal matter, when dead add organic matter along with energy into the soil which is consumed back by the producers. Some of the dead animals are fed upon by some creatures. In this way energy flows in the food chain.

 A large part of the energy is lost to environment or used up in activities like respiration and metabolic activities.