About 100 years ago, marine biologists hauled the first Vampire squid up from the depths of the sea. Since that time they still don’t know everything about them but what they do know is their physical description, habitat and adaptations, development and behavior.
Physical description
At a maximum 30 cm (1 foot) in total length, the vampire squid is of no threat to humans. Its 15 cm (6 inch) gelatinous body appears velvety jet-black, red, purple or brown, depending on location and lighting conditions. A webbing of skin connects its eight arms, each lined with rows of fleshy spines or cirri. Only the distal half (farthest from the body) of the arms has suckers. Its limpid, globular eyes which appear red or blue, also depending on lighting are proportionately the largest in the animal kingdom at 2.5 cm (1 inch) in diameter.
Mature adults have a pair of ear-like fins projecting from the lateral sides of the mantle. These fins serve as the adult's primary means of propulsion: vampire squid are said to "fly" through the water by way of flapping their fins. Their powerful beak-like jaws are said to be white as ivory. Within the webbing are two pouches wherein the tactile velar filaments are concealed. The filaments are analogous to a true squid's tentacles, extending well past the arms.
The vampire squid is entirely covered in light-producing organs called photophores. The animal has great control over the organs, capable of producing disorienting flashes of light from fractions of a second to several minutes in duration. The intensity and size of the photophores can also be modulated. Appearing as small white discs, the photophores are larger and more complex at the tips of the arms and at the base of the two fins, but are absent from the underside of the caped arms.
The chromatophores (pigment organs) common to most cephalopods are poorly developed in vampire squid. While this means the animals are not capable of changing their skin color in the dramatic fashion of shallow-dwelling cephalopods, such trickery is not needed at the pitch black depths in which they live.
Habitat and adaptations
The vampire squid is an extreme example of a deep-sea cephalopod, thought to reside at aphotic (lightless) depths from 600-900 meters (2,000-3,000 feet) or more. Within this region of the world's oceans is a discrete habitat known as the oxygen minimum zone (OMZ). Within the OMZ oxygen saturation is too low to support aerobic metabolism in most higher organisms. Nonetheless, the vampire squid is able to live and breathe normally in the OMZ at oxygen saturations as low as 3%: a feat no other cephalopod and few other animals can claim.
In order to cope with life in the suffocating depths, vampire squid have developed several radical adaptations. Of all deep-sea cephalopods, their mass-specific metabolic rate is the lowest. Their blue blood's hemocyanin binds and transports oxygen most efficiently, aided by gills with especially large surface area. The animals have weak musculature but maintain agility and buoyancy with little effort thanks to sophisticated statocysts (balancing organs akin to a human's inner ear) and ammonium-rich gelatinous tissues closely matching the density of the surrounding seawater.
At the shallower end of the vampire squid's vertical range, the view from below is like the sky at twilight: The highly sensitive eyes of deepwater denizens are able to distinguish the silhouettes of other animals moving overhead. To combat this, the vampire squid generates its own bluish light (bioluminescence) in a strategy called counter illumination: The light diffuses the animal's silhouette, effectively "cloaking" its presence from the watchful eyes below. Its own large eyes detect even the faintest of gleams. Pair of photoreceptors are located atop its head, perhaps alerting the animal to movements above.
Like other deep-sea cephalopods, vampire squid lack ink sacs. If threatened, instead of
