The Hagfish is a unique ocean creature. Though they strongly resemble eels, they are actually a primitive species of fish but many people still commonly refer to them as a slime eel, due to their ability to produce copious quantities of slime at will.
The fish is considered a living fossil. Their physiology has remained relatively unchanged for the past 300 million years. This is the only living creature known to man to possess a bony skull, but no vertebral column.
There are 76 known varieties of Hagfish throughout the world. Their classification is a constant source of debate among scientists. Their closest known living relative remains the lamprey eel.
Hagfish Physical Characteristics
The various kinds of Hagfish attain different lengths. The largest sometimes reach as much as 4 ft (1.22 m) in length. The smallest ones – only about 1.6 in (4 cm). Between the various species, an average length is about 19.7 in (0.5 m).
Their bodies grow highly elongated in form, and they also possess a distinctly paddle-shaped tail. The skin also fits loosely over their bodies.
The coloring varies between species but includes black, white, bluish gray, and even pink. The eyes are simple, leaving the Hagfish for all intents and purposes blind. Yet, they possess a keen olfactory sense to compensate.
Hagfish Habitat and Behavior
The different species of Hagfish live in most tropical and temperate waters. All are deep-dwelling fish and live on the ocean floor or at depths as great as 5,600 ft (1,800 m). There they prefer to hide beneath rocks or the sand.
The animal primarily feeds on the carcasses of dead fish. Yet, they will attack live prey on occasion and are popular for their method of feeding. They attach themselves to the body of their prey, living or dead, and burrow their way inside. Once inside, they literally consume their prey from the inside out.
If necessary, their slow metabolisms allow them to go months without feeding.