Meeting Abstract
Young Octopus bimaculoides (less than 60 days post-hatching) have well developed arms and arm-based locomotor movements. Using high-speed imaging and kinematic analyses we describe substrate associated locomotor movements in 20 young octopuses striding across a glass tank bottom. A variety of patterns of arm movement were observed for both straight movement and change in locomotor trajectory. Several key findings are that: 1. Through use of different arm combinations hatchling octopuses change movement direction without changing the orientation of the body. This has been described previously in mature O. vulgaris (Levy et al. 2015. Current Biology, 25:1195). 2. Leading arms were most likely to drive locomotion while trailing arms were regularly, but not uniformly, held above the tank floor. 3. The animals used a range of patterns of arm coordination but several were particularly prevalent. Frequently three or four arms positioned on the side of the body in the direction of movement appeared to power locomotion. We recorded several different patterns of arm coordination during locomotion. When three arms were predominantly used, we observed the central arm to alternate extension cycles with the arm to each side. We also observed cases in which the three arms moved in sequence, without synchronous placement of two arms. When four arms were used, at times the center two were observed to move synchronously and alternate with the arm to each side of the central pair while we also saw sequencing of the four arms without synchronous movement of any subset of the arms. We did not observe rhythmic bipedal locomotion, which has been described in other octopus species. Supported by US Office of Naval Research Grant # N00014-19-1-2495.
