Heterotrophic organisms use organic carbon compounds for their carbon source (Okafar, 2011). The corresponding pathways of carbon metabolism are also referred to as heterotrophic.
Etymology: from Greek έτερος (other, different) and Greek τροφή (nourishment).
To meet their cellular demand of carbon, heterotrophic organisms rely on organic carbon compounds that originate from other organisms. Examples include animals, fungi, numerous bacterial and archaeal species, and parasitic plants. The latter, however, have not been detected in aquatic environments (Rubiales and Heide-Jørgensen, 2011). In addition, many autotrophic organisms can operate heterotrophic metabolic pathways. Heterotrophic bacteria and zooplankton are important players in the microbial loop of aquatic food webs (Barber, 2007; Fenchel, 2008).