Trophic or feeding levels in an ecosystem illustrate food relationships between organisms in an area. The first trophic level is the producers or autotrophs. These are green plants or algae, capable of combining the inorganic compounds carbon dioxide and water in the presence of light energy and manufacturing an organic compound called glucose, a type of chemical energy to be eaten as food. The organisms that eat the producers are called primary consumers. These are the herbivores or plant eaters including mice, rabbits, grasshoppers. The next trophic level is called the secondary consumers which are carnivores, or flesh eaters. They eat the organisms from the previous trophic level. An example would be a frog(carnivore), which eats a grasshopper(herbivore), which eats leaves(producers). This example describes part of a food chain. The chain can continue to a snake eating the frog or even a hawk eating the snake. There are also the decomposers, part of the food chain which insures that the nutrients available in the dead organisms as well as their wastes are returned to the environment to be recycled once again. These are the bacteria and fungi. Food chains describe a way for energy to be transferred from light energy, to chemical energy(food)to keep living things alive.