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.

Full text

Vol.:(0123456789)
1 3
Marine Biology (2020) 167:36
https://doi.org/10.1007/s00227-019-3643-9
ORIGINAL PAPER
The yellow stingray (Urobatis jamaicensis) can use magnetic eld
polarity toorient inspace andsolve amaze
KyleC.Newton1,2 · StephenM.Kajiura1
Received: 20 August 2019 / Accepted: 30 December 2019 / Published online: 6 February 2020
© Springer-Verlag GmbH Germany, part of Springer Nature 2020
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.
Introduction
Orientation is an integral part of animal navigation where
an organism aligns itself with respect to an external cue
(Berthold 2001; Gould 1998) to maintain a desired head-
ing. However, calculating a heading requires thatthe animal
know its current position relative to that of its goal so that it
can determine the correct direction in which to travel (Gould
1998; 2004). The animal can then use an appropriate envi-
ronmental cue, such as visual landmarks, localized sounds
or odor gradients, the position of the sun, or the direc-
tion of thegeomagnetic field (GMF) as an external point
of reference to maintain the correct orientation. Animals
can use different types of cues to form distinct cognitive
compasses and employ them as needed when environmen-
tal stimuli cease to propagate and become unreliable (Able
1991; Gould 1998). The physical nature of a cue and how it
behaves in a medium, such as seawater, will determine how
effective that cue is for navigating over a given spatiotem-
poral scale. Cues that originate from localized sources tend
to diminish rapidly with space and time, which makes them
effective beacons or landmarks (Shettleworth and Sutton
2005; Cheng 2012) for relatively short distance navigation.
Conversely, global cues such as celestial rotation or GMF
polarity fluctuate very little over small spatiotemporal scales
and are well suited for navigational tasks that can last several
months and span thousands of kilometers.
The GMF has polarity, or a north–south directional com-
ponent, because on the surface of the Earthit is emitted from
the magnetic north pole located in the southern hemisphere
and terminates atthe magnetic south pole in the northern
hemisphere. The GMF at any geographic location can be
described by a vector with an overall intensity of 20–70 µT
and an inclination angle (measured relative to the surface of
the Earth) that ranges from + 90° to − 90°. These quantities
Responsible Editor: J. Carlson.
Reviewed by undisclosed experts.
* Kyle C. Newton
kyle.newton@wustl.edu
1 Department ofBiological Science, Florida Atlantic
University, 777 Glades Road, BocaRaton, FL33431, USA
2 Present Address: Department ofOtolaryngology, Washington
University School ofMedicine, 660 South Euclid Avenue,
Campus Box8115, St.Louis, MO63110, USA
Content courtesy of Springer Nature, terms of use apply. Rights reserved.