STELLA, M.P.*; KIER, W.M.; Univ. of N. Carolina, Chapel Hill; Univ. of N. Carolina, Chapel Hill: The Morphology and Mechanics of Octopus Arms: Inspiration for Novel Robotics

The eight arms of octopuses are used in locomotion, prey capture, feeding, manipulation and sensing of objects, grooming, and reproduction. Accomplishing such a diverse array of tasks requires remarkable flexibility, dexterity, complexity and diversity of movement. The incorporation of analogous capabilities in a human engineered robotic arm would be a significant advance in robotic technology, with diverse potential applications. As part of a collaborative project involving biologists, engineers, computer scientists, and psychologists, we are analyzing the structure, biomechanics and the musculature of octopus arms as inspiration for the design and construction of a new class of robotic arm. We used histological techniques to describe the arrangement of connective tissue and muscle in the arms of three octopus species that vary in arm proportions: Octopus briareus (�long-armed�), Octopus bimaculoides (�intermediate length arm�), and Octopus digueti (�short-armed�). The arm morphology of the three species was remarkably similar and showed the characteristics of muscular hydrostats including tightly packed muscle fibers in a three-dimensional array with no large fluid-filled cavities. In addition, we used transmission electron microscopy to examine the ultrastructure of the transverse and longitudinal arm muscle of Octopus bimaculoides. The muscle fibers are obliquely striated with comparatively long thick myofilaments, implying relatively low shortening velocity and high tension. We are currently testing these predictions by measuring the contractile properties of small muscle fiber bundle preparations. The insights gained from this analysis are being used by our collaborators in developing novel robotic arms. Supported by the DARPA (N66001-03-R-8043).