Most producers are green plants that can manufacture their food through the process of photosynthesis. Organisms that require fixed energy found in organic molecules for their survival are called heterotrophs. Heterotrophs who obtain their energy from living organisms are called consumers. Consumers can be of two basic types. Consumers that consume plants are know as herbivores.
Carnivores are consumers who eat herbivores or other carnivores.
Plants and animals supply organic matter to the soil system through shed tissues and death. Consumer organisms that feed on this organic matter, or detritus, are known as detritivores or decomposers . The organic matter that is consumed by the detritivores is eventually converted back into inorganic nutrients in the soil. These nutrients can then be used by plants for the production of organic compounds. Hence, decomposers or detritivores are heterotrophs that obtain their energy either from dead organisms or from organic compounds dispersed in the environment.