Ken Schultz's Field Guide to Saltwater Fish - Macaw Pets store

Hagfish
Atlantic Hagfish
Myxine glutinosa
98 Hagfish
Hagfish are one of two groups of jawless fish (the other
being lampreys), which are the most primitive true vertebrates.
They are members of the Petromyzontidae family.
Fishlike vertebrates, jawless fish are similar to eels in form,
with a cartilaginous or fibrous skeleton that has no bones.
They have no paired limbs and no developed jaws or bony
teeth. Their extremely slimy skin lacks scales.
The repulsive-looking hag is the most primitive of all
living fish, resembling an outsize, slimy worm. The hag
is exclusively marine, and only one family, Myxinidae, is
known. The hag has the ability to discharge slime from its
mucous sacs, which are far out of proportion to its size.
Their habit of feeding primarily on dead or disabled fish
makes hagfish doubly unattractive. Commercial fishermen
consider them a great nuisance because they penetrate the
bodies of hooked or gillnetted fish, eating out first the intestines
and then the meat, leaving nothing but skin and
bones. The hagfish bores into the cavity of its victim by
means of a rasplike tongue. Unlike many lampreys (see), it
is not a parasite. Hags’ eyes are not visible externally, and
they are considered blind. Food is apparently detected by
scent, and large numbers of hags are often taken in deepset
eel pots baited with dead fish.
The hag can be differentiated from its close relative the
lamprey, by the following characteristics: The hag has
prominent barbels on its snout, no separate dorsal fin, eyes
that are not visible externally, a nasal opening at the tip of
the snout, and a mouth that is not funnelshaped or disklike.
The largest hags are 2 feet or more in length. They range
the cold, deep waters, and at least one specimen was
recorded at a depth of 4,380 feet.