Meeting Abstract

51.6  Monday, Jan. 5  Performance Differences in Stingrays with Varying Electrosensory System Morphology JORDAN, LK*; KAJIURA, SM; GORDON, MS; Univ. of California, Los Angeles; Florida Atlantic University; Univ. of California, Los Angeles ljordan@ucla.edu

Electrosensory signals are important during the final stages of prey capture in elasmobranch fishes (sharks, skates, and rays), and may be particularly useful for dorso-ventrally flattened batoids with mouths hidden from their eyes. In stingrays, the electrosensory system extends over the dorsal and ventral body surfaces with pore numbers and densities relating to foraging habitat. This study tests functional hypotheses based on quantified differences in the electrosensory system morphology of three stingray species; the benthic round stingray, Urobatis halleri, benthopelagic bat ray, Myliobatis californica, and the pelagic stingray, Pteroplatytrygon (Dasyatis) violacea. Behavioral experiments were performed to compare responses to prey-simulating dipole electrical signals (5.3 to 9.6 μA). Electrical field intensities calculated at orientation points were similar among these species though they differed in response type and orientation pathway. Minimum voltage gradients that elicited feeding responses were well below 1 nV cm^-1 for all species. Individual stingrays most commonly displayed single turn orientations with a resulting trajectory leading directly to the center of the dipole, demonstrating the ability to determine the direction of the dipole source from afar. A small percentage of orientations included spiral tracking turns where rays appeared to follow curved voltage equipotentials to locate the center of the dipole. By quantifying the electric field intensity on both the right and left sides of the body we determined that rays conform to the predicted model by maintaining a constant voltage gradient on either side of the body midline. These results are the first to relate quantified morphological differences in electrosensory anatomy with behavioral differences in the detection capabilities of batoid fishes.