Heterotrophs are also sometimes referred to as consumers. A heterotroph, or consumer, is any organism that is unable to manufacture its own food and must feed on other organisms or organic matter.
There are three levels of consumers in the food chain. These are the primary, secondary and tertiary consumers. Primary consumers are the herbivores that feed on producers. Secondary consumers feed on producers and primary consumers. Tertiary consumers feed on producers, primary and secondary consumers.
All animals are heterotrophs or consumers. Some fungi are heterotrophs, and most bacteria are heterotrophs as well. A consumer that obtains carbon from another source is classified as a photoheterotroph or a chemoheterotroph.