Today I’m cheating a bit in my Halloween deep sea exploration series by including a vampire squid encountered by the E/V Nautilus back in 2014. What can I say? Vampire squid should be discussed at every opportunity.

Man, it really does look like a vampire.

German biologist Carl Chun first described this species in 1903 from specimens hauled up in nets. The vampire squid wasn’t observed in its habitat until decades later, so people tended to assume the worst about it based on what they could see. According to Claire Nouvian's book "The Deep", a man named William Beebe described it in 1926 as “a very small but terrible octopus, black as night with ivory white jaws and blood red eyes.” In fact, the squid appears red in real life, and its eyes can be blue too.

Contrary to appearances, vampire squid eat about the most harmless food imaginable: marine snow – the lifeless bits of sea dandruff that float down from lighter realms above (all of it dead, some of it formerly living.) You can learn more about that in a post I wrote for Halloween 2013.

They mine the plentiful harvest of marine snow found in a very hostile place: the oxygen minimum zone, where the oxygen available in the water is no more than 5% of that available in surface air. Most large animals cannot tolerate this suffocating water for more than a few minutes or hours, but vampire squid live there permanently thanks to a highly efficient respiratory blood pigment (you have one of these called hemoglobin that makes your blood red, but it is nowhere near as ninja-like as the vampire squid’s, as you will find out quickly as you climb a tall mountain.) Oxygen-minimum zone bonus: fewer predators.

Vampire squid also occupy a strange evolutionary position. They are so unusual they command their own order, a very high level of taxonomic organization. They have eight arms and fins on their head like an octopus, but they also have two long squid-like feeding filaments they use to catch and retrieve marine snow. As a result, scientists think vampire squid are extremely ancient, and may represent some of the only living descendants of the common ancestors of both octopus and squid that lived more than 200 million years ago.

There is one final spectacular aspect of vampire squid biology that few people know about: they glow. Have a look at this clip from the BBC’s Planet Earth to see what I mean:

I think it would really help the vampire squid's game if as soon as it turns on those lights, it shouts, "Bleh!!! I vannnt to suuuck your blooood!"

Instead, as a last resort in fending off predators like sea lions or deep-diving whales, the vampire squid has one final trick. Ink would be useless in the dark, so instead they eject from the ends of their arms a cloud of thick, sparkly blue mucus. The cloud can glow for up to 10 minutes, and when it fades, the vampire squid will be long gone.