Many octopuses feature an ink sack which they use whenever they are startled. This is a defense mechanism that works quite well at much lower depths of the ocean. At the bottom of the ocean, in a place where it’s pretty much pitch-dark, this is useless.
Vampire squids don’t possess such an ink sack. whenever they feel threatened, they simply start waving their 8 arms around and wrap them around their own body. This pretty much turns these creatures inside-out, a pretty remarkable sight.
