Food Chain

A food chain is a sequence of organisms through which energy passes, in the form of biomass. Some organisms eat other organisms in the chain and break down their biomass to produce ATP. All organisms use ATP to grow, generate heat, and drive cellular and body functions.

Explore this example of a food chain in the African savanna. The levels in the food chain refer to trophic levels: groups of organisms that are the same number of “feeding steps” away from the original source of energy (in this case, energy from the Sun).

Level 1: Producers

Producers, such as plants, get energy from chemical processes like photosynthesis. The sugars produced by photosynthesis become part of a plant’s structure, including its leaves, stems, and fruits.

Illustration of a leaf.

Level 2: Primary Consumers

Primary consumers are organisms that eat producers. They include plant-eating animals, called herbivores, such as antelopes. When an herbivore eats and digests a plant, it breaks down the plant’s biomass into small molecules (such as sugars) that enter the bloodstream. The bloodstream delivers these molecules to the herbivore’s cells, which convert the chemical energy in the molecules into ATP through cellular respiration.

Illustration of an impala.

Level 3: Secondary Consumers

Secondary consumers are organisms that eat primary consumers. They include meat-eating animals, called carnivores, such as lions. When a carnivore eats and digests an herbivore, it breaks down the herbivore’s biomass into small molecules that enter the bloodstream. Again, cells can convert the chemical energy in these molecules into ATP through cellular respiration.

Illustration of a lion.

Some food chains also have tertiary consumers, which are organisms that eat secondary consumers.