Food web patterns and the parasite's Perspective

Food webs are theoretical abstractions of the complex linkages and interactions that are thought to occur in nature. Although few real food webs have actually been characterized scientifically, there is a large body of literature on the processes that contribute towards complexity and stability in webs. Food webs are generally thought of as 'what eats what' webs, but parasites are not usually incorporated into webs even though parasitism is a feeding strategy shared by a majority of species on earth (70%). This chapter examines major ideas on the roles of parasites in food webs, starting with Elton's (1927) idea that parasites are analogous to predators. It describes some general patterns of parasite web structure (e.g., inverted pyramid of numbers and body size hypotheses) using both available published data and data from studies on food webs in freshwater streams in New Jersey.