Vampire squid a human's inner ear) and ammonium-rich gelatinous tissues closely matching the density of the surrounding seawater. Like many deep-sea cephalopods, the vampire squid lacks ink sacs. If disturbed, it will curl its arms up outwards and wrap them around its body, turning itself inside-out in a way, exposing spiny projections. If highly agitated, it may eject a sticky cloud of bioluminescent mucus containing innumerable orbs of blue light from the arm tips. This luminous barrage, which may last nearly 10 minutes, would presumably serve to daze would-be predators and allow the vampire squid to disappear into the blackness without the
Squid ocean temperatures and low oxygen concentrations, and makes the oxygenated blood a deep, blue color. As systemic blood returns via two vena cavae to the branchial hearts, excretion of urine, carbon dioxide, and waste solutes occurs through outpockets (called nephridial appendages) in the vena cavae walls that enable gas exchange and excretion via the mantle cavity seawater. The majority are no more than long, although the giant squid may reach . In 1978, sharp, curved claws on the suction cups of squid tentacles cut up the rubber coating on the hull of the USS "Stein". The size suggested the largest