Why do food webs consist of many predator-prey relationships?

Food chains showcase clear picture of who is eating who. But when we try to use them to characterize entire ecological communities i.e food web, certain problems arise. For example, a species may sometimes consume numerous prey types, or be consumed by several predators at various trophic levels. To even more accurately describe these interactions, we should use a food web, a chart that demonstrates most the trophic — eating-related — relationships within an ecosystem among different species.

Arrows point from a species consumed on food chains to the creature that consumes it. Some organisms that eat species from more than one trophic stage, as shown in the food web below. Opossum shrimp, for an instance, consume both primary producers as well as primary consumers. Primary producers demonstrated with green, primary consumers with orange, secondary consumers with blue while tertiary consumers with purple.