Who is whom within an community.

We can differentiate these relationships into versus those that are consumed. In particular, in order of the direction of consumption, are producers → consumers, but also consumers → consumers.

With further subdiving, these are:

Not all types are found in all ecosystems, however, and particularly absent are the higher-end consumers such as quaternary consumers.

See also trophic interactions, trophic efficiency, food chain, and food web.