Myxini

(hagfishes), a subclass of vertebrates of the class Cyclostomata. Body length, 45–70 cm. The single nasal aperture at the top of the head is connected to the pharynx. The mouth and nasal aperture are surrounded by six to eight fleshy tentacles. There are between five and 15 pairs of gill pouches. In some species, each gill pouch individually connects the pharynx to the exterior environment; in others, the pouches open into a single aperture on each side of the body. The visceral skeleton consists of a small number of cartilage plates. The venous system is not a closed circuit; it includes a main heart and three auxiliary hearts. The eyes are covered with skin, and there are light-sensitive cells around the cloaca.

The Myxini comprise a single family with approximately 15 species, distributed in temperate and subtropical waters of the world ocean. The vertebrates lay 20–30 large oval eggs (18-20 mm). In the USSR the common Atlantic hagfish (Myxine glutinosa) is occasionally encountered in the Barents Sea. Hag-fishes are predacious, eating the intestines and muscles of weak fish. Their powerful tongue with horny teeth rasps a hole through the body of the victim. Less frequently, hagfishes feed on worms. The vertebrates are capable of tying their body into a knot. Hagfishes are damaging to the fishing industry because they eat fish caught in nets.