The Hagfish

The truly amazing Hagfish are eel-shaped slime-producing marine animals, that are the only known living species to have a skull but not a vertebral column! Hagfishes are one of evolution's masterpieces. In fact, so good is the 'design' of the Hagfish that little has changed and they are literally living fossils as today's Hagfish remain virtually identical to those that lived 300 million years ago!

Hagfish average about 50 cm in length, having elongated, eel-like bodies, paddle-like tails and no true fins. Their eyes are simple eyespots that cannot resolve images, and they posses no jaws but instead have six or eight barbels around the mouth and a single nostril.

However, probably the most amazing fact about Hagfish is the copious quantities of slime or mucus it is able to exude. In fact, an adult Hagfish can secrete enough slime to turn a bucket of water into slime within minutes! When either captured or held, they secrete this micro-fibrous slime, which expands into a gelatinous and sticky goo when combined with water. If this doesn't initially allow them to escape, they can then tie themselves in an overhand knot which works its way from the head to the tail of the animal, scraping off the slime as it goes and freeing them from their captor, as well as the slime! It is also believed that there is a further protective effect of the slime and it causes impairment to the function of any predator fish's gills. Since most of the known predators of Hagfish are varieties of sea birds or mammals, it has been suggested that the lack of marine predators can be explained by this 'gill-clogging' defence to those that attempt to prey on the Hagfish. If so, it could be regarded as one of the most successful and sophisticated evolutionary strategy against predatory fish!

Free-swimming hagfish also 'slime' when agitated and will later clear the mucus off by performing the same travelling-knot behaviour. The previously noted 'gill-clogging' effect suggests that the 'tying-yourself-up-in-knots' behaviour is perhaps even necessary to restore the Hagfish's own gill function after 'sliming'. 

And finally, further research is ongoing regarding the properties and possible life-changing applications that we could use involving the components of the filamentous protein contained within the Hagfish's slime. 

The Hagfish has got to be one of nature's most ugliest but truly fascinating oddities…