Conducting the mirror test on captive manta rays
Csilla Ari, Ph.D.
The common belief is that fish are dumb. I was curious how dumb is the potentially most intelligent fish, at least based on its brain`s characteristics. But how can we measure the cognitive abilities of manta rays or any fish at all? There is a test that is universally accepted to measure whether an animal has self-awareness, self recognition. The mirror test was developed by Gallup, in 1970 and only a few species passed it so far, e.g. some apes, african elephant, magpie, bottlenose dolphin. The common characteristics of these species are the relatively large, well developed brain and highly social behavior. During this test the animal is first exposed to a mirror, if it shows social responses, agression or looks behind it is unlikely that has self awareness. But if it shows self inspection by doing repetitive, unusual movements that suggests self awareness. At this stage a visible mark is applied on one side of the body and if the animal exposes that marked body part more often to the mirror than other sides that would be interpreted as self inspection, self awareness. For example bottlenose dolphins made unusual turns in front of the mirror and blew bubbles indicating self inspection. I thought if manta rays have the largest brain of all fish than probably they have the best chance to pass the mirror test if any fish can at all. So it might sound strange at first, but we actually exposed captive manta rays to a mirror and we experienced something unexpected. The manta rays not only spent much more time in the area front of the mirror, but they exposed their belly to the mirror repetitively and even created bubbles somehow, similarly to what was observed with dolphins.
These exciting experiments will be continued in 2016. Stay tuned!
Our paper on manta ray cognition is now published in the Journal of Ethology!
First behavioral experiments on cognitive abilities of manta rays