A food web combines several related food chains. It shows the many kinds of relationships that exist in a natural community. For example, in the first illustration, the angler may not only catch and eat pike, he may also take perch. Similarly, pike may feed on mosquito larvae and dragonfly larvae, as well as perch. Algae and many other aquatic plants are eaten by a variety of invertebrates and fish.
Invertebrates are important in the food webs of most water and land communities.
Without decomposers, the minerals, gases and water that make up living things would not be returned to the soil and air, where green plants again use these materials to make food.