The Vampire Squid (Vampyroteuthis infernalis) is the single living representative of the cephalopod group known as the Vampyromorpha. It is a small (mantle length to 13 cm), gelatinous species that occurs in mesopelagic to bathypelagic depths (typically between 600 and 1200 m) in temperate and tropical waters of the Pacific, Atlantic, and Indian Oceans. At these depths, sunlight is limited or entirely absent, oxygen content is low, and temperatures range from about 2° to 6° C. In the North Pacific, V. infernalis occurs as far north as the Aleutian Islands.
When observed in its natural habitat, the Vampire Squid has the appearance of a robust and substantial animal, but this impression is somewhat misleading. In fact, its body is very soft, with watery tissues and little dense musculature. It has a very low metabolic rate and lives at extremely low oxygen concentrations, yet it is capable of relatively high swimming speeds, relying on its fins rather than jet propulsion. Although several authors have suggested that Vampire Squids mainly move passively like jellyfish, recent work has shown that, despite having a metabolic rate lower than that measured for any other cephalopod (and, indeed, comparable to many jellyfishes), adult Vampire Squids engage in fairly active fin swimming. This is a more energetically efficient mode of locomotion than the jet propulsion more typical of cephalopods, including juvenile Vampire Squids.
Light production by Vampire Squids has been observed from large, paired, complex photophores at the bases of the fins, from organs at the tips of all eight arms, and from luminous fluid released by the arm tips (Robison et al. 2003).
Based on limited evidence, Vampire Squids have been reported to feed upon copepods, prawns, and cnidarians. Examination of ingested items from captured specimens has shown that these items included the remains of gelatinous zooplankton, discarded larvacean houses, crustacean remains, diatoms and faecal pellets. Remarkably, recent investigations Hoving and Robison 2012) have revealed that Vampire Squids obtain much or all of their energy as detritivores, i.e., from non-living particles captured from the water column, as discussed in this video from the Monterey Bay Aquarium Research Institute (all other known cephalopods actively capture live prey). Vampire Squids are themselves eaten by deep-diving fishes, pinnipeds, whales, and benthopelagic fishes (based on the presence of Vampire Squid beaks in the stomachs of these predators).
The Vampire Squid combines morphological features associated with both octopuses and squids and cuttlefishes. Although based on morphological comparisons the Vampire Squid has been proposed to be the sister group to the octopods, based on their molecular phylogenetic analyses Yokobori et al. (2007) question this conclusion and suggest that unless new data provide greater resolution, the octopods, the Vampire Squid, and the squids and cuttlefishes should be recognized as the three major groups of non-nautiloid cephalopods.
The Vampire Squid's name refers to its jet-black skin, the caped appearance of the webbing between the arms, and eyes that appear red under some light conditions. The great naturalist explorer William Beebe (1926, cited in Seibel et al 1998) described the Vampire Squid as "a very small but terrible octopus, black as night, with ivory white jaws and blood red eyes", although modern observations indicate that it is actually a rather docile animal.
(Seibel et al. 1998 and references therein; Robison et al. 2003 and references therein; Bower et al. 2006)