Gyrocotyloidea

a class of parasitic flatworms that occupies a position intermediate between tapeworms and monogenetic flukes. The body length is usually 2-3 cm, more rarely up to 10 cm. There are five species (the independence of some species is in dispute); they live in the spiral valve (of the intestinal tract) of chimaeras (deep-sea fishes); they are found in various regions of the world ocean. Characteristic of Gyrocotyloidea are the absence of an intestinal tract and presence of a complexly constructed rosette-like organ for attachment on the posterior end of its body. From the oval egg, which is equipped with a peduncle, a larva develops, the so-called lycophore, with ten identical hooks on its posterior end. The cycle of development is apparently direct. Many assign Gyrocotyloidea to the subclass Cestodaria of the class Cestoidea (tapeworms); some consider them highly modified monogenetic flukes.