Hemiurus

Hemiurus is a genus of trematodes, commonly known as digenetic flatworms, that are parasitic in the digestive tracts of fish. These parasites are found worldwide in both marine and freshwater environments. The life cycle of Hemiurus typically involves at least two intermediate hosts. The first intermediate host is usually a small aquatic invertebrate, such as a snail or a crustacean, where larval stages develop. A second intermediate host, often a fish, ingests the infected first intermediate host. The parasite then matures into an adult within the digestive system of the second intermediate host. Adult Hemiurus are characterized by a distinct body shape, often with a prominent oral sucker and a ventral sucker, and a uterus that is typically coiled and fills a large portion of the hindbody. They are hermaphroditic, possessing both male and female reproductive organs. While Hemiurus are common parasites of fish, they generally do not cause significant harm to their hosts, though heavy infections can sometimes lead to reduced growth or other minor pathological effects. Humans are not known to be infected by Hemiurus.