The food chain consists of autotrophs (producers) and heterotrophs (consumers). All animals and plants fall into these categories.
The autotrophs are the first stage of the food chain. They are mostly plants. They use the radiation from the sun to fulfill their energy needs. In doing this process the autotrophs release oxygen. The process is known as photosynthesis. The plants take in carbon dioxide in the atmosphere released by heterotrophs during respiration and the plants in turn release carbon dioxide. Also, autotrophs provide a food source for the heterotrophs.
Every producer and consumer interact in some way, completing food chain.
