Meeting Abstract

61.3  Jan. 7  Autotomy as a deep-sea squid defense BUSH, S.L.; University of California, Berkeley & MBARI stephalopod@berkeley.edu

In oceanic midwaters animals are vulnerable to predation from all directions, therefore it is likely that a diversity of defensive tactics are employed by deep-sea organisms. One maneuver is to startle a predator upon attack such that the predator flees in confusion or hesitates long enough to allow the potential prey’s escape. This may be the mechanism utilized by the mesopelagic squid, Octopoteuthis deletron. Handled specimens lost distal arm portions that continued to move for several seconds while the single, large photophore of each arm-tip bioluminesced. In situ observations confirmed that arm loss occurs naturally. Some individuals were missing up to one half of an arm and tissue regeneration was clearly in progress in several specimens. Histology revealed the presence of fracture planes in the arm musculature, making this the first known deep-sea squid with the ability to autotomize arms. Dropping one or more arms that continue to move and bioluminesce might hinder predatory attempts. The potential continuous loss and regeneration of tissue is surprising given the energetic limitations of deep-sea organisms.