Consumer (food chain)

Spotted hyenas with a stolen kill of an Impala. Hyenas are one example of a tertiary consumer that rely on the feeding of other organisms for survival.

Consumers are organisms of an ecological food chain that receive their energy by consuming other organisms. These organisms are formally referred to as heterotrophs, which are includes animals, bacteria and fungus. Some insectivorous plants, such as the Venus flytrap, consume insects for some of their energy intake, but still heavily rely on photosynthesis.

Within an ecological food chain, consumers are categorized into three groups: primary consumers, secondary consumers, and the tertiary consumers. Primary consumers are usually herbivores, feeding on plants and fungus. Secondary consumers, on the other hand, are mainly carnivorous and prey other animals. Omnivores, who feed on both plants and animals, can also be considered as a secondary consumer. Tertiary consumers, sometimes also known as an apex predator, are usually on top of a food chain, capable of feeding on secondary consumers and primary consumers. Tertiary consumers can be either fully carnivorous or omnivorous. Humans are one such example of a tertiary consumer.

Consumers make up the majority of the trophic levels of a food chain and play essential ecological roles within their habitats by controlling the population of certain organisms to prevent them from overpopulating that would otherwise damage the health and the biodiversity of an ecosystem. Invasive species introduced by human activities are often classified as tertiary consumers and are one of the main contributions to damaging ecosystems, due their situation of not having any natural predators within their introduced habitats. This would result in competition of resources, space, the overconsumption of other organisms, and the spread of diseases to native biodiversity.

See also

• Ecosystem
• Food chain
• Primary producers