Meeting Abstract

99.5  Saturday, Jan. 7  Behavioral sensitivity of batoid elasmobranchs to prey-simulating electric fields BEDORE, CN*; HARRIS, LL; KAJIURA, SM; Florida Atlantic University; Florida Atlantic University; Florida Atlantic University

Elasmobranchs are renowned for their electrosensory capabilities and sensitivity to electric fields has been quantified for numerous species. However, tremendous diversity in morphology, behavior, and habitat is present throughout the group and may confer adaptations in sensory system function. We tested the electrosensitivity of two morphologically, behaviorally, and ecologically diverse batoids, the cownose ray, Rhinoptera bonasus, and the yellow stingray, Urobatis jamaicensis (order Myliobatiformes). We predicted that electrosensory morphology may impart differences in electrosensitivity. We measured bioelectric fields of prey items and generated biologically relevant stimuli that were employed in behavioral assays. The yellow stingray demonstrated greater electrosensitivity than the cownose ray. Although the cownose ray possessed a greater number of electrosensory pores than the yellow stingray, most pores were concentrated on the ventral surface of the head, near the mouth and cephalic lobes. Conversely, the yellow stingray lacks cephalic specialization and its pores were more widely distributed across the body. Behavioral differences between the two species, rather than morphology, likely explain much of the discrepancy in electrosensitivity. Cownose rays are bentho-pelagic and spend much of their time in schools at the water surface, but prey primarily on benthic molluscs and may rely on cues other than electroreception until the last moments of prey localization. In contrast, the yellow stingray is exclusively benthic and feeds opportunistically on cryptic invertebrate prey, which demand greater sensitivity for detection. This study demonstrates that dramatic differences in sensory systems exist and that generalizations about sensory function may be inadequate, even within a closely related group.