Meeting Abstract

57.1  Jan. 6  Patterns of fin ray curvature of Myoxocephalus octodecimspinosus, the longhorn sculpin during substrate-contact and swimming TAFT, Natalia K.; University of Massachusetts Amherst natashak@bio.umass.edu

The pectoral fins of benthic fished are used for substrate contact behaviors as well as during swimming. Morphological specializations of the fin rays are correlated with this functional flexibility in several groups. For example, in benthic suckers, flatfishes and blennies, fin rays that routinely contact the substrate are generally shorter and thicker, lack distal branching and exhibit reduced webbing compared to rays that are not involved in substrate interactions. However, the specific contribution of individual fin rays during pectoral fin behaviors is not well understood. To characterize the role of different fin rays in a benthic species, I measured fin ray curvature during both substrate-contact and swimming behaviors in four individual longhorn sculpin. To calculate curvature, six equally spaced points along every other pectoral fin ray were digitized. The 3-D coordinates for each point were used to fit splines to each ray. Curvature data were then calculated from each spline at 10% increments along the length of each fin ray. In all groups, curvature of the rays was higher during substrate-contact than during swimming. During both behaviors, curvature was consistently highest in the two most ventral rays digitized, followed by the next two most ventral and the two most dorsal rays. The four middle rays showed the least absolute curvature and smallest difference in curvature between the two behaviors. In general, the regions of the fin ray in all rays with the highest curvature were the most proximal 15% of the ray and the most distal third. The potential structural underpinnings of the differences in bending among pectoral fin rays will be further explored using clearing and staining and CT scanning techniques.