These are parasites of the intestine of fish-eating birds. Adult parasites are usually harmless, but the larval diplostomulum stage can be a serious problem for the fish second intermediate host because it prefers to live in tissues such as the eye, where it can obsure vision by crawling over the lens, and the brain, where it can cause neurological problems. These types of pathogenesis enhance transmission by making its host more susceptible to predation by a fish-eating bird. This genus possesses a glandular tribocytic organ on the ventrum of the fore-body.