The feeding relationships that exist in an ecosystem can be shown by a food chain. The arrows represent the direction of energy flow and mean 'gets eaten by'.
Not all the energy is passed from one level of the food chain to the next. About 90 per cent of energy may be lost as heat (released during respiration), through movement, or in materials that the consumer does not digest.
The energy stored in undigested materials can be transferred to decomposers. Decomposers are organisms such as bacteria and fungi that can obtain energy by breaking down dead organisms.