Meeting Abstract
Ghost crabs are highly active invertebrates capable of remarkable bursts of speed, as well as prolonged bouts of sustained locomotion. This study was initiated to develop better insight into how the circulatory system of the ghost crab, Ocypode quadrata, supplies blood to active skeletal muscles used to power locomotion. During fast sprints, the large leg muscles extend and flex the carpopodite at up to more than ten times per second. Mammalian skeletal muscles exhibit significant differences in capillary supply, based on the metabolic demands of a particular muscle, with aerobic fibers exhibiting greater capillary densities than glycolytic fibers. We perfused blood vessels with a polymerizing resin to visualize the arterial supply to the skeletal muscles of the merus. We also stained excised arteries with a variety of dyes and antibodies to elucidate their cellular and molecular organization. The results of these complementary techniques were that the entire leg is supplied by a single artery that runs along the length of the limb – midway between the dorsal and ventral borders. This artery gives rise to several smaller arteries that arise at regular intervals and then branch extensively to supply the muscle fibers of the leg. The terminal branches of this system are similar in dimension to vertebrate capillaries, and these vessels are comprised of a simple layer of squamous cells. The overall results show that the skeletal muscles are nourished by an extensive blood supply. The existence of an essentially closed arterial system in these crabs is consistent with patterns observed in other decapod crustaceans. We propose that the extensive, well-defined arterial blood supply in the ghost crabs is integral to supporting their running abilities.
