Consumer (biology)

A consumer, also called a heterotroph, is an organism that feeds on organic matter. The opposite are producers or autotrophic organisms, which produce their own food. Consumers can be grouped into herbivores (or primary consumers, which only eat plants), carnivores (or secondary consumers), which eat animals, and omnivores (which eat both plants and animals). Top predators that feed on other carnivores (in addition to other members of the food chain) are considered tertiary consumers.

Between 60 and 90% of the food eaten by consumers is oxidized to obtain energy to move and produce internal heat. There is always a part of the food that is not digested, such as much of the cellulose or fiber (the walls of plant cells), which is excreted. The remaining percentage is used to create body tissues (to grow, restore or store as fat), requiring nutrients (vitamins, minerals and proteins). This amount of energy used in body growth is the only one that can be used by consumers of the higher level, who, likewise, will only take advantage of a minimum part for their growth. This occurs successively at each food level (or trophic level), so that the overpopulation or disappearance of a trophic level can affect all other levels of an ecosystem.

Consumer classes

From an ecological point of view, or what is the same, from the use of other beings, consumers are classified as primary (herbivores), secondary (carnivores) and tertiary (they feed on secondaries). Quaternary consumers are those beings that feed on both vegetables and secondary and tertiary consumers.

• Herbivores. They feed on different parts of the plant, which may be these roots, stems, leaves, flowers, fruits or seeds or substances previously prepared by the plant, as the bees do, which use the nectar of the flowers.
• Carnivores. They use the energy they store other animals:
  • Predators. They feed on the animals they hunt.
  • Parasites. They feed on other animals, but not kill them.
  • Cartoons. They feed on bodies or remains of other beings.
• Omnivores. They feed on both other animals and plants and more.
• Detritivores. They feed on waste.