If this energy comes from light then these organisms are called photosynthetic autotrophs . In most ecosystems plants are the dominant photosynthetic autotroph. 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 that consume plants are know as herbivores .
Carnivores are consumers who eat herbivores or other carnivores.
Decomposers or detritivores are heterotrophs that obtain their energy either from dead organisms or from organic compounds dispersed in the environment. Once fixed by plants, organic energy can move within the ecosystem through the consumption of living or dead organic matter. Upon decomposition the chemicals that were once organized into organic compounds are returned to their inorganic form and can be taken up by plants once again. Organic energy can also move from one ecosystem to another by a variety of processes. Inputs and outputs of energy and matter in a typical ecosystem.