1. Energy is transferred along food chains from one trophic level to the next.
2. The amount of available energy decreases from one stage to the next.
3. This is because not all the food can be fully digested and assimilate.
4. Hair, feathers, insect exoskeletons, cartilage and bone in animal foods, cellulose and lignin in plant foods cannot be digested by most animals.
5. These materials are excreted or made into pellets of indigested remains.
6. Assimilated energy is available for the synthesis of new biomass through growth and reproduction.
7. Organisms also lose some biomass by death disease or annual leaf-drop.
8. Moreover at each tropic level, organisms use the most of the assimilated energy to fulfill their metabolic requirements – performance of work, growth and reproduction.
9. Most of the energy is lost in the form of heat during biological processes.
10. Only a small fraction goes to the consumer at next tropic level.
