Figure 3.

In many second intermediate hosts (hosts of the second larval stage) of trematode parasites – like the California killifish (Fundulus parvipinnis) – the parasite induces behavioral changes to facilitate transmission to the final host (in this example, bird predators). (a) In the absence of parasites, fish display evasive and camouflaging behavior that minimizes the likelihood of bird predation. (b) When trematode metacercariae (larval stage) infect killifish, the fish perform behaviors that make them conspicuous to bird predators, effectively increasing the availability of fish resources to birds (Lafferty and Morris 1996). In this way, parasites may provide a “subsidy” to predators. Such behavioral manipulations are common across the diversity of parasite life.