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
Bigfin reef squid (particularly dolphins), who use echolocation to find prey. Bigfin reef squids exhibit two most common social body patterning and posturing behaviours related to mating. The first is dubbed "accentuated gonads", in which they will sometimes increase the visibility of their gonads while reducing the rest of their body colouration. This makes their reproductive organs appear bright white through the transparent mantle. It may indicate the reproductive condition of the signalling squid. Another common behaviour, primarily seen in males, is dubbed "spread arms", in which the squid will slightly tilt its body forward, head down and arms spread widely and raised