Meeting Abstract

49.5  Saturday, Jan. 5  Swimming spines of sharks PORTER, ME*; ROQUE, CM; SUMMERS, AP; University of California, Irvine; University of California, Irvine; University of California, Irvine porterm@uci.edu

Maneuverability is a characteristic of locomotion that is difficult to assess, and can be measured as the turning radius of an animal, turning speed, the ability to accelerate off-axis, or even as rotational instability. Flexibility is a morphological measure that correlates with maneuverability and is the maximum curvature (lateral displacement) in a swimming animal. In addition to influencing swimming mode, flexibility dictates aspects of feeding, reproductive and antagonistic behaviors. The flexibility of a shark is influenced by the vertebral column and the musculotendinous system pulling on the vertebral column. Increasing vertebral column flexibility has been modeled in two ways; either by increasing vertebral number or joint angle while holding the other variable constant. Despite that relatively simple model of vertebral column flexibility, previous research on three species of Carcharhinid sharks has shown total vertebral number does not correlate with flexibility. The goals of this study were to quantify flexibility in shark species with varying swimming modes and describe the morphology (number of vertebrae, angle between vertebrae, fineness ratios of vertebrae, intervertebral joint length) of the vertebral column. We quantified maneuverability by filming live sharks in southern California aquaria. Vertebral column morphology was obtained from the swimming sharks when possible or from museum and lab specimens. We have also found that total vertebral number does not correlate with flexibility. However, vertebral shape and intervertebral joint length may make greater contributions to increasing flexibility in swimming sharks.