Our planet is inhabited by a host of strange and remarkable creatures, but few as strange or remarkable, if you ask me, as hagfish. Hagfish are eel-like fish about a foot long. They have a small mouth that lacks jaws and teeth.
Hagfish can produce large quantities of slime in a matter of seconds. What could possibly be the use in producing large quantities of slime? Why, defense of course! Wouldn't you like to throw a bucket of slime at one of your enemies?
While slime may merely irritate a human enemy, it can suffocate underwater predators by clogging their gills. Again, we're not talking about a tiny bit of slime, but as much as a milk jug full, which is about how much slime a single hagfish can produce at one time. One of the proteins in the slime is a long strand that when secreted is wound up tight like a ball, but as soon as it hits the water, it unravels. This unraveling plays a crucial role in the slime's swelling in volume as it enters water.
In order to clean the slime off its body, so that it doesn't suffocate along with its predators, the hagfish ties itself into a knot. Then it skillfully passes this knot down its body, a process that wipes the slime away from its body.