HUFFARD, CL*; FULL, RJ; University of California, Berkeley; University of California, Berkeley: Underwater bipedal locomotion by octopuses in disguise

Here we report an under-water, bipedal movement using a hydrostatic skeleton rather than rigid support. Octopus marginatus and Octopus (Abdopus) aculeatus move bipedally on the ventral pair of arms while using the other six arms for camouflage. The animal is pushed back along the sand as each arm tip alternates rolling along the sucker edge. This locomotion differs from normal crawling by octopuses, in which several arms are sprawled around the body, being pushed and pulled along by the suckers in no regular sequence (Mather, 1998). Underwater video allowed initial kinematic analyses of bi-pedal locomotion. Duty factors for O.marginatus and O.aculeatus exceeded 0.50. Speed of O.marginatus did not exceed 0.1m/s (2.6 mantle lengths/s). Mather, J.A. 1998. J. Comp. Psych. 112:306-316