Hagfish information and info on the Myxinidae also known as Hagfishes
Hagfish are marine craniates(Bony skulls) of the class Agnatha or Myxini, also known as Hyperotreti. Some researchers regard Myxini as not belonging to the subphylum Vertebrata. That is, they are the only living animals that have a skull but not a vertebral column.
Despite their name, there is some debate about whether they are strictly fish (as there is for lampreys), since they belong to a much more primitive line than any other group that is placed in the category of fish.
The earliest fossil record dates back approximately 550 million years, or earlier to the Lower Cambrian period.
Their unusual feeding habits and slime-producing capabilities have led members of the scientific community and popular media to dub the hagfish as the most "disgusting" of all sea creatures.
Although hagfish are sometimes called "slime eels", they are not eels at all.
In my personal opinion I would class them closer to slamanders than fish.
Hagfish average about half a metre (18 in) and he largest known species is Eptatretus goliath with a specimen recorded at 127 cm, while Myxine kuoi and Myxine pequenoi seem to reach no more than 18 cm.
Hagfish have elongated, eel-like bodies, and paddle-like tails.
They have cartilaginous skulls (although the part surrounding the brain is composed primarily of a fibrous sheath) and tooth-like structures composed of keratin.
Colors depend on the species, ranging from pink to blue-grey, and black or white spots may be present.
Eyes are simple eyespots, not compound eyes that can resolve images.
Hagfish have no true fins and have six or eight barbels around the mouth and a single nostril. Instead of vertically articulating jaws like vertebrates with jaws, they have a pair of horizontally moving structures with tooth-like projections for pulling off food.
The mouth of the hagfish has two pairs of horny, comb-shaped teeth on a cartilaginous plate that protracts and retracts. These teeth are used to grasp food and draw it toward themselves.