Superclass: Agnatha (jawless fish)
This pacific hagfish (Eptatretus stoutii) was caught offshore from a depth of 600m. Although once thought to be parasitic, these guys are now known to scavenge off dead carcasses. They don't possess jaws, so they tend to rasp the flesh off their meals with their tongue, and tie themselves into knots, to tear chunks off (for an example check out the end of Blue planet's the Deep episode).
They only have a partial cranium and lack vertebrae, which has often led scientists to reclassify hagfish outside of the vertebrata (who all are characterized by a complete skull around their brains). However, developmental processes regulating cranial and vertebral patterns are similar for hagfish and other vertebrates, which lends weight to the idea that hagfish do belong within the vertebrates .
The hagfish is also known by the name slime eels. These guys produce a slime which contains fibrous threads, allowing for major cohesion of the slime wad. Best guess is the slime is a defense mechanism used to clog the gills of the would-be predator. Love puts it best: "Hagfish produce truly gargantuan amounts of slime. We are talking major league quantities here. Your average hagfish can take a bucket full of water and solidify it with slime in a few minutes." Says it all, really.