Hagfish

There are no two ways about it, hagfish are grim from the gills up.

Where most animals’ defence mechanisms consist of things like venoms, aggressive displays, thick armour, super speed and agility or some badass spines, the hagfish has taken a decidedly oozier approach.

When the hagfish, an eel-like deep sea fish, feels threatened, it will exude large amounts of fibrous, viscous slime. This not only makes them tricky to get a good grip on, but will almost immediately clog up the gills and mouthparts of anything that tries to eat it. If the slime gets too much for even the hagfish, it can sort of scrape it off by literally tying itself in knots and sloughing off its coat of mucous.