Vampyroteuthis infernalis, literally "vampire squid from hell," is a species of bioluminescent squid that can be found at extreme depths (around 3,000 ft) in most oceans around the globe.
The vampire squid has a appearance unlike that of any other squid. Looking more like an octopus, it gets its name from the sets of sharp spines found underneath any of its eight arms (most squids have humble suckers). Unlike octopi and like squids and cuttlefish, the vampire squid has a pair of tentacles. It also has a pair of wing-like fins attached to the head which are used as a propulsion mechanism. To top it all off, it has a set of two bioluminescent eyes. One of the first humans to stumble across this beast described it as a "terrible octopus, black as night with ivory white jaws and blood red eyes". The vampire squid can be of several varieties of color including black, red and purple.
Not much is really known about the behavior of this creature, however it has been observed that it exhibits a method of underwater movement more commonly seen in seals, turtles and penguins than in other cephalopods. When threatened, if you call poking a giant camera-arm from a submersible a threat, the vampire squid folds its arms around the top of its head, exposing the sharp spines beneath them. Additionally, it has been found that the squid secretes a fluid of bioluminescent stuff to aid in escaping from predators.
For more information on V. Infernalis see http://www.dal.ca/~ceph/TCP/vampy.html or execute a search on your favorite search engine.
Quotes and general info pulled from http://www.dal.ca/~ceph/TCP/vampy.html , James B. Wood