Consumers are organisms that receive all their energy by consuming other types of organisms or organic matter. Generally consumers prey on other organisms because they do not have the ability to produce their own energy or to obtain energy through inorganic sources.
There are three levels of consumers in an ecological food chain: primary, secondary and tertiary consumers. Primary consumers are also known as herbivores and only eat plants and fruits. Secondary consumers eat primary consumers and are known as carnivores. Tertiary consumers eat secondary and primary consumers and are also known as carnivores. Consumers known as omnivores eat both plants and animals and can be either secondary or tertiary consumers.