Cognitive and magnetosensory ecology of the yellow stingray, Urobatis jamaicensis

Elasmobranchs (sharks, skates, and rays) migrate across a wide range of
spatiotemporal scales, display philopatry, seasonal residency, and maintain
home ranges. Many animals use the Earth’s magnetic field to orient and navigate
between habitats. The geomagnetic field provides a variety of sensory cues to
magnetically sensitive species, which could potentially use the polarity, or
intensity and inclination angle of the field, to derive a sense of direction, or
location, during migration. Magnetoreception has never been unequivocally
demonstrated in any elasmobranch species and the cognitive abilities of these
fishes are poorly studied. This project used behavioral conditioning assays that
paired magnetic and reinforcement stimuli in order to elicit behavioral responses.
The specific goals were to determine if the yellow stingray, Urobatis jamaicensis,
could detect magnetic fields, to quantify the nature of the magnetic stimuli it could
detect, and to quantify the learning and memory capabilities of this species. The results supported the original hypotheses and demonstrated that the yellow
stingray could: discriminate between magnetic and non-magnetic objects; detect
and discriminate between changes in geomagnetic field strength and inclination
angle; and use geomagnetic field polarity to solve a navigational task. The yellow
stingray learned behavioral tasks faster and retained the memories of learned
associations longer than any batoid (skate or ray) to date. The data also suggest
that this species can classify magnetic field stimuli into categories and learn
similar behavioral tasks with increased efficiency, which indicate behavioral
flexibility. These data support the idea that cartilaginous fishes use the
geomagnetic field as an environmental cue to derive a sense of location and
direction during migrations. Future studies should investigate the mechanism,
physiological threshold, and sensitivity range of the elasmobranch magnetic
sense in order to understand the effects of anthropogenic activities and
environmental change on the migratory ability of these fishes.