A successful ecosystem depends on the exchange of energy between organisms. This energy is passed on from individual to individual through feeding. Different species are grouped together based on what they eat, and these groupings are called trophic levels.
There are four basic trophic levels, but it is possible to have five or six as well. In the bottom level are the producers, and then come the plant eaters, the meat eaters, and the detritovores (organisms that feed on organic remains from the decay of other organisms). All of these levels exchange life-giving energy.
Different trophic levels both give and take energy from one another in a linkage referred to as a food web or food chain. I'm sure you've heard of the food chain before right? Food webs are very complex, and biologists have yet to discover all of the ins and outs of how they work. A simplified version of a food web would function like this: plant grows, animal eats plant, animal eats animal who ate plant, both animals and plants die, and are in turn eaten by smaller organisms (detritovores), who convert this organic material back into organic compounds in soil that can be taken up again by plants. So it is a circular pattern just like a spider's web!
There are two types of food webs that make up the larger, more general definition of food webs: grazing webs and detritus webs.
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