Explanation:

Energy enters most communities as light, where it is absorbed by autotrophs (e.g. plants) and converted into chemical energy via photosynthesis
Energy then gets passed to the primary consumer (herbivore) when they eat the plant, and then gets passed to successive consumers (carnivores) as they are eaten in turn
Energy is lost between trophic levels in the form of heat through cell respiration, faeces, tissue loss and death.
Some of this lost energy is used by detritivores and saprotrophs. These in turn also lose energy in the form of heat through cell respiration