The vampire squid (Vampyroteuthis infernalis) is a small cephalopod found in temperate and tropical oceans in extreme deep-sea conditions. As a phylogenetic relict, it is the only known surviving member of its order.
The vampire squid can reach a maximum total length of 30cm. Its 15cm gelatinous body varies in colour from jet-black to pale reddish, depending on location. A webbing of skin connects each of its eight arms, each lined with rows of fleshy spines. The inner side of this “cloak” is black. Only the halves farthest from the body are the arms that have suckers. Its spherical eyes, which appear red or blue, depending on lighting, are proportionately the largest in the animal kingdom at 2.5 cm diameter. The name of the animal was inspired by its dark colour, cloak-like webbing, and red eyes, rather than habit—it feeds on waste and debris, not blood.
The vampire squid is an example of a deep-sea cephalopod, thought to reside at aphotic depths from 600 to 900 metres or more. Within this region of the world’s oceans is a discrete habitat known as the oxygen minimum zone. Within the zone, the saturation of oxygen is too low to support aerobic metabolism in most complex organisms. Nonetheless, the vampire squid is able to live and breathe normally in the minimum zone at oxygen saturations as low as 3%.