At Taskinas Creek , they also found signs of infection by a fiddler crab virus. Crabs at the Goodwin Islands have different parasites from those at Taskinas. Especially those that use herons and other wading birds. Many parasites have more than one host, he explained. For example, a parasitic worm might live in a fiddler as a juvenile, yet reach sexual maturity as the parasite of a Great Blue Heron.
Fiddlers are key players in marsh food webs.
When a heron eats one, young parasites hitch a ride. Parasite eggs reach fiddlers via heron excrement. A more familiar case of a parasite that uses two hosts is a tapeworm, which a dog could get from ingesting its intermediate host- a flea. Fiddlers are a productive species. Shields has calculated population densities as great as 250,000 per acre at the Goodwin Islands.