Meeting Abstract

105.5  Sunday, Jan. 6  Are you positive? Discrimination between poles of electric fields by elasmobranch fishes. SICILIANO, AM*; PORTER, ME; KAJIURA, SM; Vassar College; Vassar College; Florida Atlantic University avsiciliano@vassar.edu

Elasmobranch fishes use electroreception to detect cryptic prey at close range. Behavioral assays demonstrate that they respond to prey-simulating dipole electric fields by sharply turning and biting at the electrodes. However, it is unknown whether they are able to discriminate between positive and negative poles, and, if they can, whether they prefer to bite at one pole or the other. To address these questions, and hence to better understand the mechanisms underlying elasmobranch electroreception, we employed behavioral assays to test whether the yellow stingray (Urobatis jamaicensis) can distinguish between the positive and negative charges of an electric dipole in a saltwater tank. We used positive food rewards to train rays to only bite at one pole of a dipole electric field. We trained two groups of animals: one group (N=6) was trained to feed from the positive pole and the other group (N=7) was trained to feed from the negative pole. After training daily for 4 weeks, yellow rays were scored based on their responses to polarity. We found that rays preferred to bite at the pole to which they were trained. This successful training is the first evidence that elasmobranch fishes may be able to resolve the orientation of a localized electrical field. This perceptual ability may have consequences not only for detecting prey, but also for short and long range navigation, since the geomagnetic field varies locally and globally. In addition, elasmobranch fishes may perceive underwater cables and power supplies with unknown biological consequences.