Figure 18.18 Food webs. Food webs capture the full diversity of species and species interactions in the community. In this North American lake, the major producers are the plants along the shoreline and the phytoplankton in the water. These producers are eaten by a variety of primary consumers, as indicated by the arrows that illustrate the flow of energy from an organism to the species consuming it. This food web also includes secondary consumers, such as bluegill sunfish, tertiary consumers, such as the great blue heron, and decomposers, such as bacteria.