Visual discrimination and resolution in freshwater stingrays (Potamotrygon motoro)

Abstract

Potamotrygon motoro has been shown to use vision to orient in a laboratory setting and has been successfully trained in cognitive behavioral studies using visual stimuli. This study explores P. motoro’s visual discrimination abilities in the context of two-alternative forced-choice experiments, with a focus on shape and contrast, stimulus orientation, and visual resolution. Results support that stingrays are able to discriminate stimulus-presence and -absence, overall stimulus contrasts, two forms, horizontal from vertical stimulus orientations, and different colors that also vary in brightness. Stingrays tested in visual resolution experiments demonstrated a range of visual acuities from < 0.13 to 0.23 cpd under the given experimental conditions. Additionally, this report includes the first evidence for memory retention in this species.

A shark's eye view: testing the ‘mistaken identity theory’ behind shark bites on humans

“…A spacing parameter of 5 cpd was used, based on estimates of the maximum anatomical spatial resolving power obtained from analysis of the retinas of two juvenile white sharks (electronic supplementary material, figure S1). Previous studies in elasmobranchs indicate that, in most cases, behavioural and electrophysiological estimates of spatial resolving power are substantially lower than anatomical estimates [33,34,41–43]. Thus, we also modelled motion cues using a spacing parameter of 2.5 cpd, which more closely reflects the spatial resolving power across the majority of the retina (i.e.…”

It’s all about seeing and hearing: the Editors’ and Readers’ Choice Awards 2022

“…In the Original Paper category, the votes cast in the first round revealed a more complex picture. Three articles (Brandt et al 2021;Daniel et al 2021;Lin and Hedwig 2021) received 4 (out of 16) points each, reflecting the difficulty of the Editorial Board to select a top candidate from many excellent contributions. In the second round of voting, the majority of the Editorial Board members voted for the article on 'Visual discrimination and resolution in freshwater stingrays (Potamotrygon motoro)' by Daniel et al (2021).…”

“…In the first issue of the Journal, Friedrich Schiemenz presented a novel conditioning paradigm to examine color vision in sticklebacks and minnows (Schiemenz 1924). Daniel et al (2021) used a similar behavioral approach, in which one visual stimulus was associated with food reward while the other was not, to explore, in the laboratory, various aspects of visual discrimination abilities of the ocellate river stingray (Potamotrygon motoro). The Editorial Board was impressed by the exemplary detailed behavioral analysis carried out by the authors, which provides an excellent foundation for future field studies and laboratory experiments combining behavioral analysis with anatomical work.…”

Counting on Numbers—Numerical Abilities in Grey Bamboo Sharks and Ocellate River Stingrays

“…Several elasmobranch species, including the grey bamboo shark ( Chiloscyllium griseum ) and the ocellate river stingray ( Potamotrygon motoro ), have been part of a range of cognition experiments and have shown various visual discrimination as well as orientation abilities (see reviews [ 42 , 43 , 44 , 45 , 46 , 47 , 48 , 49 , 50 , 51 , 52 , 53 ]). Adding to that, freshwater stingrays ( Potamotrygon castexi ) are able to use water as a tool to extract food from a tube [ 54 ].…”

“…They also performed well in a range of optical illusion experiments [ 50 , 58 ]. In recent studies a wide range of visual discrimination abilities were shown in P. motoro , including first evidence for memory retention [ 45 ], serial reversal learning [ 46 ] and colour discrimination [ 45 ]. In addition, C. griseum and P. motoro both seem to be able to use spatial maps to orientate, can use different orientation strategies and memorize spatial tasks over a period of several weeks or months [ 51 , 59 ].…”