hagfish

Primitive marine fish lacking true jaws, vertebrae, paired fins, and scales; includes Myxina glutinosa, widespread in the N Atlantic and Arctic; body eel-like, covered in copious slime, length up to 60 cm/2 ft; mouth slit-like surrounded by stout barbels; burrows in soft mud, feeding off invertebrates and fish. (Family: Myxinidae, 3 genera.)

iHagfish
Pacific hagfish resting on bottom 280 m down off Oregon coast
Scientific classification
Kingdom: Animalia Phylum: Chordata Subphylum: Vertebrata Class: Myxini Order: Myxiniformes Family: Myxinidae
Genera
Eptatretus Myxine Nemamyxine Neomyxine Notomyxine Paramyxine Quadratus

This article is about the hagfish. For the Punk Rock band, see Hagfish (band).

A hagfish is a marine chordate of the class Myxini, also known as Hyperotreti.

Hagfish enter both living and dead fish, feeding on the insides (polychaete marine worms are also prey).

Recent molecular biology analyses tend to classify hagfish as vertebrates (see references), their molecular evolutive distance from Vertebrata (sensu stricto) being short.

The circulatory system of the hagfish has both closed and open blood vessels, with a heart system that is the most primitive of all vertebrates, bearing some resemblance to that of some worms.

Individual hagfish are hermaphroditic, with both ovaries and testes, but the female gonads remain non-functional until the individual has reached a particular stage in the hagfish lifecycle.

In recent years hagfish have become of special interest for genetic analysis investigating the relationships among chordates. Some of the species are listed here:

Genus Eptatretus: Inshore hagfish, Eptatretus burgeri (Girard, 1855) New Zealand hagfish, Eptatretus cirrhatus (Forster, 1801) Black hagfish, Eptatretus deani (Evermann & Goldsborough, 1907) Guadalupe hagfish, Eptatretus fritzi Wisner & McMillan, 1990 Sixgill hagfish, Eptatretus hexatrema (Müller, 1836) Shorthead hagfish, Eptatretus mcconnaugheyi Wisner & McMillan, 1990 Eptatretus mendozai Hensley, 1985 Eightgill hagfish, Eptatretus octatrema (Barnard, 1923) Fourteen-gill hagfish, Eptatretus polytrema (Girard, 1855) Fivegill hagfish, Eptatretus profundus (Barnard, 1923) Cortez hagfish, Eptatretus sinus Wisner & McMillan, 1990 Gulf hagfish, Eptatretus springeri (Bigelow & Schroeder, 1952) Pacific hagfish, Eptatretus stoutii (Lockington, 1878) Genus Myxine: Patagonian hagfish Myxine affinis Günther, 1870 Myxine australis Jenyns, 1842 Cape hagfish, Myxine capensis Whiteface hagfish, Myxine circifrons Garman, 1899 Myxine debueni Wisner & Snyder, 1901 Hagfish (or Atlantic hagfish), Myxine glutinosa Myxine hubbsi Wisner & McMillan, 1995 White-headed hagfish, Myxine ios Myxine jespersenae Møller, Feld, Poulsen, Thomsen & McMillan, 1995 Myxine kuoi Mok, 2002 Myxine limosa Girard, 1859 Myxine mccoskeri Wisner & McMillan, 1995 Myxine mcmillanae Hensley, 1991 Myxine paucidens Regan, 1913 Myxine pequenoi Wisner & McMillan, 1995 Myxine sotoi Mincarone, 2001 Genus Nemamyxine: Nemamyxine elongata Richardson, 1958 Nemamyxine kreffti McMillan and Wisner, 1982 Genus Neomyxine: Neomyxine biniplicata (Richardson and Jowett, 1951) Genus Notomyxine: Notomyxine tridentiger (Garman, 1899) Genus Paramyxine: Paramyxine atami Dean, 1904 Paramyxine cheni Shen and Tao, 1975 Paramyxine fernholmi Kuo, Huang and Mok, 1994 Paramyxine sheni Kuo, Huang and Mok, 1994 Paramyxine wisneri Kuo, Huang and Mok, 1994 Genus Quadratus: Quadratus ancon Mok, Saavedra-Diaz and Acero P., 2001 Quadratus nelsoni (Kuo, Huang and Mok, 1994) Quadratus taiwanae (Shen and Tao, 1975) Quadratus yangi