Meeting Abstract

4.1  Saturday, Jan. 4 08:00  Pectoral fin muscular architecture of batoids in relation to ecological lifestyle GABLER, MK*; FISH, FE; COUGHLIN, DJ; University of North Carolina Wilmington; West Chester University of PA; Widener University mkg5178@uncw.edu

Batoid fish swim using two different modes of locomotion, undulation and oscillation. To achieve these locomotory modes, batoids have evolved enlarged pectoral fins with distinct muscle layers. The structure of the underlying musculature in the pectoral fins are expected to explain some of the ecological differences seen among species utilizing these particular swimming modes. CT scans of 15 species of batoids were classified according to swimming mode to measure the absolute volume of the dorsal, abductor muscle and the ventral, adductor muscle. Histochemical methods including succinate dehydrogenase (SDH) and immunofluoresence were used to determine the different fiber types comprising these muscle masses in three batoid species (Dasyatis sabina, Potamotrygon motoro, and Rhinoptera bonasus). Species that swam by oscillation of the fins had an equal volume of abductor and adductor muscle in the pectoral fins, whereas undulatory species had a larger volume of abductor muscle compared to adductor muscle. Oscillatory species, which are primarily pelagic in lifestyle, have equivalent volumes of muscle in association with generating equal forces on the up and down strokes. Oscillatory species were shown to possess a higher proportion of slow oxidative, red fibers in their muscular bundles, while undulatory species had a higher proportion of fast glycolytic, white fibers. The differences in the muscle architecture and composition observed between oscillatory and undulatory batoids is associated with the differing lifestyles of members of the group.