The thorny-headed worm family Polymorphidae contains endoparasites which as adults feed mainly in fish and aquatic birds. When this taxon was erected by Meyer in 1931, a subfamily Polymorphinae was established in it. As the Polymorphidae as presently understood would then be monotypic, with no basal genera outside the Polymorphinae, the proposed subfamily is redundant for the time being and therefore most modern treatments simply omit it. Polymorphus minutus is an economically significant parasite in goose and duck farming.
Plagiorchiida is a large order of trematodes, synonymous to Echinostomida. They belong to the Digenea, a large subclass of flukes. This order contains relatively few significant parasites of humans.
Centrorhynchidae is a family of parasitic worms. Three species of these thorny-headed worms in the genus Centrorhynchus were found to parasitize birds of prey and owls Slovakia. These hosts include Buteo buteo, Buteo rufinus, Falco tinnunculus, Asio otus, Strix aluco, Strix uralensis and Tyto alba.
Rhadinorhynchidae is a family of parasitic worms from the order Echinorhynchida.
Dorylaimia is a subclass of nematodes.
Opecoelidae is a family of trematodes. It is the largest digenean family with over 90 genera and nearly 900 species, almost solely found in marine and freshwater teleost fishes. It was considered by Bray et al. to belong in the superfamily Opecoeloidea Ozaki, 1925 or the Brachycladioidea Odhner, 1905.
Stenurus is a genus of nematode that infects cetaceans.
Allopodocotyle is a genus of trematodes in the family Opecoelidae.
Decemtestis is a genus of trematodes in the family Opecoelidae. It has been synonymised with Allodecemtestis Hafeezullah, 1970.
Diplobulbus is a genus of trematodes in the family Opecoelidae.
Neonotoporus is a genus of trematodes in the family Opecoelidae.
Opecoelus is a genus of trematodes in the family Opecoelidae.
Opegaster is a genus of trematodes in the family Opecoelidae.
Caudotestis is a genus of trematodes in the family Opecoelidae.
Pseudaliidae is a family of nematodes belonging to the order Strongylida.
Syphacia is a genus of nematodes belonging to the family Oxyuridae.
Micracanthorhynchina is a genus of worms belonging to the family Rhadinorhynchidae.
Falcaustra is a genus of nematodes belonging to the family Kathlaniidae.
Dichelyne is a genus of nematodes belonging to the family Cucullanidae.
