Meeting Abstract
Many species of elongate fishes use anguilliform swimming to propel themselves through the water. During anguilliform swimming, a fish passes a wave of motion from the head, through the body, to the tail producing thrust; but some long-axis rotation of the body also occurs. In dorsal view, alternating views of the lateral side of the fish can be seen as the wave passes along the body. The amount of the lateral surface visible changes along the body as well as by species. We quantified this long-axis roll, or wobble, on a scale from 0 (no lateral surface visible) to 1 (complete lateral surface visible). Wobble data from three species of elongate fishes, Apodichthys flavidus, Xiphister atropurpureus, and Lumpenus sagitta, were compared using an automated video analysis developed in MatLab, which we also used to compute wave parameters (tail beat frequency, wave speed, amplitude). We found that wobble increased with wave speed (SL/s) and tail beat frequency (hz), and was independent of total speed (SL/s) and maximum amplitude (SL). The mobility and deformation forces of fish vertebral joints (and biomimetic propulsors) is bound to be a major determinant of the emergent property of wobble.
