Euhaplorchis californiensis is a trophically transmitted parasite (TTP) that lives in the salt-water marshes of Southern California, United States.
Once the parasite has lived in the snail a couple of generations, the cercariae (the disk-shaped larvae of flukes of the class Trematoda, which have a tail-like appendage) swim out into the marsh.
According to Kevin D. Lafferty, infected killifish are four times more likely to “shimmy, jerk, flash, and surface” than uninfected fish.
Once the fish is consumed, the parasite lives in the bird's gut and produces eggs to be released in the stool, which is spread into the marshes and ponds.
He also claims that the susceptibility of infected killifish to be picked up by their avian predators has led to a diverse and abundant assemblage of piscivorous birds along the coasts.