Plants produce their own food, while animals must eat other organisms to survive. Plants make their own food via the process of photosynthesis, which involves using the sun's energy to convert water and carbon dioxide into sugar.
Because plants produce their own food, they are known as producers. Animals are called consumers because they must eat plants or other animals to stay alive. Primary consumers, also called herbivores, are plant eaters. Deer eat the leaves, buds and needles of trees and shrubs.
Secondary consumers, called carnivores, eat other animals. The lion is an example of a carnivore. Omnivores eat both plants and animals, giving them a wider variety of foods to consume. Bears are omnivorous because they eat berries as well as elk, bison and other animals.
Other plants and creatures in the world of food producers and consumers are the decomposers. These are fungi and certain insects such as the Goldsmith beetle. Decomposers feed on dead organisms or the waste from living organisms.
Producers, consumers and decomposers are all part of the food chain. This shows who eats whom or what, and how the energy from the food is transferred from one organism to the next. It is also known as a food pyramid because there are more creatures at the bottom of the pyramid, such as insects, than at the top where the large predators, who eat the most and are the least in number, belong. There are many overlaps in who eats what so the system of producers, consumers and decomposers may be called a food web.