The yellow stingray (Urobatis jamaicensis) can use magnetic field polarity to orient in space and solve a maze

Abstract

Elasmobranch fishes (sharks, skates, and rays) have been hypothesized to use the geomagnetic field (GMF) to maintain a sense of direction as they navigate throughout their environment. However, it is difficult to test the sensory ecology and spatial orientation ability of large highly migratory fishes in the field. Therefore, we performed behavioral conditioning experiments on a small magnetically sensitive species, the yellow stingray (Urobatis jamaicensis), in the laboratory. We trained individuals to use the polarity, or the north–south direction, of the GMF as a cue to orient in space and navigate a T-maze for a food reward. Subjects were split into two groups that learned to associate the direction of magnetic north or south as the indicator of the reward location. Stingrays reached the learning criterion within a mean (± SE) of 158.6 ± 28.4 trials. Subjects were then reverse trained to use the previously unrewarded magnetic stimulus of the opposite polarity as the new cue for the reward location. Overall, the stingrays reached the reversal criterion in significantly fewer trials (120 ± 13.8) compared to the initial procedure. These data show that the yellow stingray can learn to associate changes in GMF polarity with a reward, relearn a behavioral task when the reward contingency is modified, and learn a reversal procedure faster than the initial association. These data support the idea that the yellow stingray, and perhaps other elasmobranchs, might use GMF polarity as a cue to orient and maintain a heading during navigation.