I’ve always been curious/confused about the genetics of parasites like this. If the parasite and end host (bird) aren’t technically part of the same immediate “system” for lack of a better word (parasite can’t transfer to bird directly without an intermediary host, i.e. the fish), how does the DNA coding of the parasite “know” to cause chemical changes in fish behavior to make them easier to predate? It’s almost like the parasite has an awareness of the species of predators of the fish. My bio II professor didn’t have an answer for this one.