The yellow stingray (Urobatis jamaicensis) can discriminate the geomagnetic cues necessary for a bicoordinate magnetic map

Elasmobranch fishes (sharks, skates, and rays) are hypothesized to use environmental cues, such as the geomagnetic field (GMF), to navigate across the ocean. However, testing the sensory and navigation abilities of large highly migratory fishes in the field is challenging. This laboratory study tested whether the yellow stingray, Urobatis jamaicensis, could detect and distinguish between the GMF cues used by other magnetically sensitive species to actively determine their location. Stingrays were divided into two cohorts for initial behavioral conditioning: one was trained to associate a change in GMF intensity with an aversive stimulus, whereas the other was trained using a change in GMF inclination angle. Individuals from each cohort remained naive to the GMF conditioning stimulus used to condition the other cohort. The combined group learned the initial association within a mean (± SE) of 184.0 ± 34.8 trials. Next, stingrays from each cohort were randomly exposed to their original GMF conditioning stimulus and the novel GMF stimulus. The original magnetic stimulus continued to be reinforced, whereas the novel stimulus was not. The group demonstrated a significantly different response to the original (reinforced) and novel (non-reinforced) stimuli, which indicates that stingrays could distinguish between the intensity and inclination angle of a magnetic field. This experiment is the first to show that a batoid (skate or ray) can detect and distinguish between changes in GMF intensity and inclination angle, and supports the idea that elasmobranchs might use GMF cues to form a magnetically based cognitive map and derive a sense of location.