Sunday, June 12, 2011
The vampire squid reaches a maximum total length of around 30 cm (1 ft). Its body varies in color between velvety jet-black and pale reddish, depending on location and lighting conditions. A webbing of skin connects its eight arms, each lined with rows of fleshy spines; the inside of this "cloak" is black. Its globular eyes, which appear red or blue, are proportionately the largest in the animal kingdom at 2.5 cm (1 inch) in diameter.
The Vampire Squid is almost entirely covered in light-producing organs called photophores. The animal has great control over the organs, capable of producing disorienting flashes of light for fractions of a second to several minutes in duration.
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 in a strategy called counterillumination: The light diffuses the animal's silhouette, effectively "cloaking" its presence from the watchful eyes below.
Like many deep-sea cephalopods, vampire squid lack ink sacs. If threatened, instead of ink, a sticky cloud of bioluminescent mucus containing innumerable orbs of blue light is ejected from the arm tips. This luminous barrage, which may last nearly 10 minutes, is presumably meant to daze would-be predators and allow the Vampire Squid to disappear into the blackness without the need to swim far.