Hagfish
\n| Hagfish |
|---|
\n
\nPacific Hagfish resting on bottom
\n280m down off Oregon coast |
\n |
|---|
\n| \n\n |
\n| Genera |
|---|
\n\nEptatretus
\nMyxine
\nNemamyxine
\nNeomyxine
\nNotomyxine
\n |
\nA
hagfish is any of several marine
chordates of the class
Myxini, also known as
Hyperotreti. They are long, vermiform, and exude a sticky slime (from which the typical species
Myxine glutinosa was named). They tie themselves in knots and scrape the slime off themselves to clean themselves.
Instead of vertically articulating
jaws like
vertebrates (
Gnathostomata), 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 pulled to the surface.
Hagfish are traditionally included amongst 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.
As unique trait, hagfish can use a knot to pull themselves out the places where they feed.
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. It has also recently been discovered that the mucus excreted by the hagfish is unique in that it includes strong, threadlike fibres similar to
spider silk. Research continues into potential uses for this or a similar synthetic gel or of the included fibres. Some possibilities include new biodegradable
polymers, space-filling gels, and as a means of stopping blood flow in accident victims and surgery patients.
About 64 species are known, in 5 genera. A number of the species have only been recently discovered, living at depths of several hundred metres. Some of the species are listed here:
Genus
Eptatretus:
- Inshore Hagfish, Eptatretus burgeri\n* Black Hagfish, Eptatretus deani\n* Gulf Hagfish, Eptatretus springeri\n* Pacific Hagfish, Eptatretus stoutii
Genus
Myxine:
- Cape Hagfish, Myxine capensis\n* Hagfish (or Atlantic Hagfish), Myxine glutinosa\n* 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, 1997)
