|
|
Food
is energy, and energy makes life possible. All living things must nourish
themselves in order to survive. Because many animals nourish themselves by eating
plants or other animals, a food chain is created. Food chains do not exist in
isolation, but form an intricate network of interrelationships—a food web.
|
Trophic Level: One strata of a food web, where organisms are the same number of steps removed from the primary producers. |
Plants are the first stage (or trophic level) of a food chain. Plants are called producers (or autotrophs—"self-feeders") because they produce energy from simple raw materials, such as sunlight and inorganic nutrients.
As soon as an animal eats a plant, a food chain is formed. All animals are heterotrophs ("other-feeders"), since they find energy by consuming other living things.
How do food chains form?
 |
|