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 is given to reproduction; the female "Onychoteuthis banksii" for example, sheds its feeding tentacles on reaching maturity, and becomes flaccid and weak after spawning. The squid mantle cavity is a seawater-filled sac containing three hearts and other organs supporting circulation, respiration, and excretion. Squid have a main systemic heart that pumps blood to the general circulatory system, and two branchial hearts that pump specifically to the gills. The systemic heart consists of three chambers, a lower ventricle and two upper atria, which are all contractile. The blood contains the copper-rich protein, hemocyanin, which is used for oxygen transport at low