Hagfish

Hagfish
Pacific hagfish resting on bottom, 280m down off Oregon coast
Scientific classification
Kingdom: Animalia Phylum: Chordata Class: Myxini Order: Myxiniformes Family: Myxinidae
Genera
Eptatretus[?] Myxine[?] Nemamyxine[?] Neomyxine[?] Notomyxine[?]

A hagfish is any of several marine chordates of the class Myxini. They are long, wormlike, and covered in sticky slime (which is what the name of the typical species Myxine glutinosa means). They tie themselves in knots and scrape the slime off themselves to clean themselves.

Instead of a vertically moving jaw like most vertebrates, they have a pair of horizontally moving structures with toothlike projections for pulling off food. They enter both living and dead fish, feeding on the insides. Marine worms are also prey. They tend to be quite common in their range, sometimes becoming a nuisance to fisherman by devouring the catch before it can be gotten to the surface.

Hagfish are traditionally included among the vertebrates as part of the jawless fish, originally grouped as a class or superclass Agnatha, and in particular were considered closely related to lampreys[?]. This relationship no long appears to be the case, and as they have continuous notochords with no segments they are commonly placed outside the vertebrates proper. The vertebrates and hagfish together make up the craniates.

Hagfish are eaten in Japan, and their skin is made into "eel leather" in Korea.

In recent years hagfish have become of special interest for genetic analysis investigating the relationships among chordates.

About 64 species are known, in 5 genera. A number of the species have only been recently discovered, living at depths of several hundred meters.

Genus Eptatretus:

• Inshore hagfish Eptatretus burgeri
• Black hagfish Eptatretus deani
• Gulf hagfish Eptatretus springeri
• Pacific hagfish Eptatretus stoutii

Genus Myxine:

• Cape hagfish Myxine capensis
• Hagfish (or Atlantic hagfish) Myxine glutinosa
• White-headed hagfish Myxine ios

Reference

• J.M. Jørgensen, J.P. Lomholt, R.E. Weber and H. Malte (eds.), The biology of hagfishes (London: Chapman & Hall[?], 1998)