Hagfærir

Hagfærir, the Icelandic term for hagfish, are primitive jawless marine animals in the order Myxiniformes. They are among the most ancient craniates, lacking jaws and true vertebrae, yet possessing a cartilaginous skull and a persistent notochord.

They are elongated, eel-like animals, usually scaleless, with a slimy skin. They have sensory barbels around the mouth and keratinized tooth-like plates used to rasp flesh. Hagfærir are found in cold marine waters worldwide, from coastal shallows to deep slopes, with many inhabiting the North Atlantic regions near Iceland. They are bottom-dwellers that feed primarily at night.

A distinctive feature is their ability to produce large quantities of slime from glands along their body. When disturbed, they exude mucus that can expand in seawater and clog gills of potential predators or handling equipment, giving them a measure of protection.

Diet consists of dead and dying fish, worms, and other small invertebrates. They often enter carcasses and use their keratinized dental plates to tear flesh.

Reproductive biology is poorly documented; eggs and spawning behavior are not well known, and much remains to be learned about hagfish reproduction.

In human affairs, hagfærir are of limited commercial importance but are sometimes fished for meat and byproducts in certain regions, and their slime can complicate capture and processing. Taxonomically, hagfishes are jawless craniates, traditionally placed with lampreys in Cyclostomata; their exact relationship to other vertebrates is a topic of ongoing study.