Muscle System of Gyrocotyle urna (Plathelmintes, Gyrocotylida)

The musculature architectonics of the body, the attachment organs, and the genital ducts of Gyrocotyle urna is described. It is shown that the lateral folds of the body and the rosette blades are characterized by the least amount and variety of musculature. In the integument, the position of each spine is regulated by three muscle groups. Most of the genital ducts are surrounded by a muscular plexus. The sucker-like organ is characterized by an extreme concentration of musculature. It is distinguished from the suckers of flukes by its inverse proportionality in the degree of development of the radial muscles, on the one hand, and other muscle groups, on the other. The functional load of various muscle groups and the mechanisms of helminth fixation and locomotion are discussed.