A food chain is a series of organisms each dependent on the next as a source of food. It consists of different trophic levels: the first level is occupied by autotrophs or producers, the second by herbivores or primary consumers, ...

The two main components of an ecosystem are biotic components (living organisms) and abiotic components (non-living physical factors).

Consumers are organisms that depend on producers, either directly or indirectly, for their sustenance. They consume the food produced by producers or by feeding on other consumers. Consumers are classified as herbivores (plant-eaters), carnivores (meat-eaters), omnivores (eating both plants and ...

Examples for each category of consumers include: herbivores like deer and rabbits; carnivores like lions and eagles; omnivores like humans and bears; and parasites like tapeworms and fleas.