<P> Consumers are organisms of an ecological food chain that receive energy by consuming other organisms . These organisms are formally referred to as heterotrophs, which include animals, some bacteria and fungi . Such organisms may consume by various means, including herbivory, predation, parasitization, and biodegradation . </P> <P> Some carnivorous plants, like the Venus flytrap, are classified as both . </P> <P> Within an ecological food chain, consumers are categorized into three groups: primary consumers, secondary consumers, and the tertiary consumers . Primary consumers are herbivores, feeding on plants . Secondary consumers, on the other hand, are carnivores, and prey on other animals . Omnivores, who feed on both plants and animals, can also be considered a secondary consumer . Tertiary consumers, sometimes also known as apex predators, are usually at the top of food chains, capable of feeding on secondary consumers and primary consumers . Tertiary consumers can be either fully carnivorous or omnivorous . </P>

Consumers in the food chain are ranked according to