With recent news that the cleaner wrasse might have mirror self-recognition (MSR), I thought I’d write about the ocean animals that have MSR. Bottlenose dolphins and killer whales have MSR for certain. Possible mirror self-recognition ocean animals include manta rays and cleaner wrasses. Ocean animal that failed the mirror self-recognition test is the octopus.
So what is self-recognition? With a mirror, self-aware animals such as chimpanzees and bottlenose dolphins recognize themselves and don’t react as if the image is another animal of the same species. Some animals that don’t have self-recognition react to their image in a mirror with aggression or other more positive social behaviors.
The mirror self-recognition test is when a human researcher places a mark somewhere conspicuous on a captive animal. With human babies, they place a paint mark on their foreheads. Starting at 18 months, human babies investigate the mark when they see themselves in a mirror.
Then the researchers place the test animal in front of a mirror and judge from their actions (usually curiosity) if they recognize themselves or not. Here are some examples from the ocean:
• Bottlenose dolphins in captivity react to a mirror image by “opening their mouths, sticking out their tongues and showing novel behaviors.” When marked, they investigate the mark on their bodies by moving the marked area towards the mirror.
• Killer whales in captivity were shown themselves unmarked in a mirror. Then they were marked. The whales behaved like they expected their appearance to be altered. This showed that they have self-recognition.
• Manta rays possibly show mirror self-recognition. When captive manta rays had a mirror placed in their tank, they blew bubbles, which they normally don’t do. They also appeared to investigate their image in the mirror by turning their belly towards the mirror and swimming by the mirror repeatedly.
• Cleaner wrasses were injected with a mark, which is how scientists mark fish in their studies. When their throats were marked and a mirror placed in their tank, the cleaner wrasses would rub their throats against the tank. Throat rubbing is not behavior seen in wild cleaner wrasses. When the mirror wasn’t in the tank, the wrasses didn’t rub. So seeing the mark in the mirror caused the throat rubbing and hence cleaner wrasses possibly have self-recognition.
As a side note, the inventor of the mirror self-recognition test, Gordon Gallup of the State University of New York, doesn’t think cleaner wrasses have self-recognition and that the study was flawed. What do you think?
• Octopuses haven’t passed the mirror test, but in studies they do orient themselves towards the mirror. Octopuses rely on their sense of touch and don’t rely on vision as much as mammals do, so it makes sense they don’t show mirror self-recognition.
On a personal note, I have dived with manta rays off the coast of Hawaii. I looked them in the eye and saw straight into their soul. It was no different than looking into a dog or cat’s eyes. I knew something was going on behind them. I don’t doubt that manta rays are thinking beings and that they may be self-aware.
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