Caryophyllaeidea

an order of unsegmented tapeworms with a single sexual apparatus. Length, 2-95 mm; width, 0.5-5 mm. The anterior portion of the body is most often widened like a fan and lacks organs of attachment. Less frequently it has 2-6 sucking pits. Adult worms (except representatives of the genus Archigetes) parasitize the intestines of cyprinoid fishes. The life cycle includes one intermediate host, the oligochaete worms, which are infected when they ingest mature ova of the parasite, which are found in the soil. In the intestine of the intermediate host an embryo hatches from the ovum, which penetrates the worm’s body cavity and develops into a larva—the procercoid. The fish becomes infected with Caryophyllaeidea by ingesting oligochaete worms infected with procercoids. Representatives of the genus Archigetes attain sexual maturity in the intermediate host. Some species of Caryophyllaeidea are pathogenic parasites of fish and are injurious to fish farming.