Researchers have been left surprised after discovering that a tropical fish called a cleaner wrasse (Labroides dimidiatus) was fully self-aware after it recognized its own reflection in a mirror. This clever little fish can be added to the list of mammals and birds who also recognize themselves and passed the test to show that they have self-awareness.
According to ScienceAlert, the mirror self-recognition test (MSR) is quite an old one and was originally used by psychologist Gordon Gallup in his work with chimpanzees back in the 1970s.
To test these chimpanzees who had never before encountered mirrors, Gallup discovered that at first glance these chimpanzees initially viewed their reflections as threatening. However, as time passed, the reality that what they were actually seeing was simply a reflection of themselves began to dawn on them, with the chimpanzees eventually preening themselves before the mirror.
As time marched on, dolphins, elephants, and even pigeons were found to pass the MSR test and recognize themselves. Even manta rays and ants have shown that they too may have self-awareness in this way.
The newest research on the cleaner wrasse tropical fish that recognizes itself in the mirror was conducted by an international team of scientists from Germany, Japan, and Switzerland to see if they could find proof that there were other species who were also self-aware.
A Tiny Fish Just Passed a Classic Self-Awareness Test With a Mirror https://t.co/OzbtzlmbNI— ScienceAlert (@ScienceAlert) August 31, 2018
The research of determining whether a species recognizes itself in a mirror is complex and usually revolves around it spotting something out of the ordinary about itself in a mirror.
For instance, if this same test were to be conducted on a human, researchers might place funny things on their bodies such as paint, which would cause the humans to spot this immediately in a mirror and then proceed to feverishly wipe it off. What this shows is that the human is completely aware that what they are touching is part of their own body. This means that the species being tested needs to have both vision and the capacity to understand that there is something unusual about itself reflecting back in the mirror.
As the cleaner wrasse has excellent vision, scientists determined that this tropical fish would be an excellent candidate for their new research, especially as they are also adept at detecting parasites lurking on other fish which they then rip off using their mouths, showing their ability to detect unusual things.
At the start of their research, the tropical fish reacted in much the same manner as other species had before it, by perceiving that the reflection in the mirror was a threat. However, as the days passed, the cleaner wrasse began to dance before the mirror, something that was considered highly out of the ordinary for this particular type of fish as they are generally known for being solitary.
Researchers continued their experiment with the self-awareness test by affixing bold splashes of colored gel onto eight of the cleaner wrasse to see if they would notice it in the mirror. It was discovered that seven out of eight of these tropical fish spent much longer than they normally would before the mirror looking at the gel, while some of them also appeared to attempt to take the gel off by brushing up against other objects where the gel was.
So while there is still some debate looming as to whether these tropical fish are truly self-aware and recognize themselves in a mirror or whether they view the colored gel as parasites on other fish, it does appear as though there may now be another species that have passed the mirror self-recognition test.