The jewel squid, of the genus Histioteuthis, also is a member of the colloquially-known cock-eyed squid family, so called due to its unique ocular appearance. Like other cock-eyed squids, the jewel squid possesses a normal-sized right eye, and a bulging, tumescent left eye. The left eye is minimally twice the size of the right, and lends the squid a squinting appearance.
The diet of the jewel squid is much like its other squid counterparts, although much smaller in scale. Jewel squid rise several meters from the depths at night to feast on krill, small shrimp and fish, the tops of jellyfish and other tiny sea creatures. Unlike other bioluminescent sea organisms, the jewel squid does not use its photophores to attract and entrance prey, and instead relies on its quick moves and the element of surprise.
The jewel squid is one of several small squids in the Histioteuthidae family. These mesopelagic-dwelling cephalopods live between 650 and 3300 feet, dozing during the day at greater depths before rising to upper levels of the sea to hunt at night. The mismatched eyes of the jewel squid are positioned so that the larger eye points upwards, to scan for food, while the smaller eye can watch beneath the squid for predators. Jewel squids do not grow to more than 35 cm.
The jewel squid is so named because of the brightly sparkling bioluminescent photophores that cover its entire body. These photophores are special organs belonging to light-producing fish and organisms of the sea. The photophores of the jewel squid are unique and incredibly complicated, and can boast the range of any special lighting effect with reflectors, a bioluminescent light source, special muscles to direct the light, lenses and even colored screens to affect the light's hue.
The jewel squid lives in extremely pressurized conditions, up to several thousand feet under the ocean's surface. Globally located, the jewel squid can be found in the relatively warm waters just off the coasts of California and South America, in the mountainous depths of the mid-Atlantic ridge and in the southernmost quadrant of the Indian ocean. The jewel squid is not without predators in these waters; this genus has been found in the stomachs of sharks, sperm whales and swordfish.