Meeting Abstract
39.2 Friday, Jan. 4 Morphology of the cephalic lobes and anterior pectoral fins in batoids MULVANY, Samantha*; MOTTA, Philip; Univ. of South Florida, Tampa; Univ. of South Florida, Tampa smulvany@mail.usf.edu
Cephalic lobes are modified portions of the anterior pectoral fins, found only in the more derived rays. Cephalic lobes vary by species, ranging in number and mobility. In basal rays lacking the cephalic lobes, the anterior pectoral fins are used in prey detection and capture, as well as locomotion. In derived rays, the cephalic lobes are involved in prey detection, excavation, manipulation, and capture. This study compares the skeleton, musculature, and electrosensory pore densities of the cephalic lobes and anterior pectoral fins in three stingrays representing different head shapes. Dasyatis sabina is a basal ray lacking cephalic lobes, Aetobatus narinari is a derived ray with one cephalic lobe, and Rhinoptera bonasus is a derived ray with two kinetic cephalic lobes. By examining the musculature, the number and type of joints of the radial cartilages, and the electrosensory pore density, it is possible to infer motor control and prey detection capabilities. Muscles originate on the propterygial cartilage and insert down the length of the radials for all species. In derived rays with kinetic cephalic lobes, there is an increase in the number of muscles on the dorsal side controlling cephalic lobe movements. The radials have multiple hinge joints that vary in number depending upon the species and the position of the radial along the propterygial cartilage. The basal rays have an increased number of joints, particularly at the tips of the radials, where the radials are bifurcated. Electrosensory pore densities are higher in R. bonasus, with less uniformity of the pore distributions. While the sensory pores are uniformly spread over the anterior pectoral fins in basal rays, the sensory pores in R. bonasus are concentrated around the edges of the cephalic lobes. The implications for prey detection and capture are discussed with regard to these findings.
