Writing in the Atlantic Jill Lepore writes about elephants that pass the mirror test and concludes that this is “proof” that they are self-aware. She writes that to date that only humans, chimps and dolphins have passed this test. That is incorrect. A veritable carnival of animals have been shown to do so, Magpies pass the test as well. Should we take the magpie data as evidence that self-awareness obtains in a far wider range of animals than we might have thought, or, as evidence that the mirror test is not in fact a test of self-awareness? But magpies turn out to be the least of our problems. Consider the lowly fish the cleaner wrasse, Labroides dimidiatus.
Masanori Kohda and colleagues report:
When … provided with a coloured tag in a modified mark test, fish attempt to remove the mark by scraping their body in the presence of a mirror but show no response towards transparent marks or to coloured marks in the absence of a mirror.
Kohda et. al. are agnostic in what we should make of these findings. Are the fish self-aware? Perhaps you can give a reason to think the mirror test has not been properly applied in this case. Or perhaps you can argue that it does not have significance for some species that it does for others. Otherwise, you are stuck with the choice of embracing an extraordinary range of creatures with self-awareness or of disavowing the implications of the test, even where it seems most plausible – for chimps. Some people are willing to do just that.
Daniel Povinelli thinks chimpanzee mirror behavior can be explained without the need for self-awareness. It is enough that the chimp notices that the body in the mirror looks and moves the same as its own body, and then makes the connection that if there is a spot on the body in the mirror, there could also be a spot on its own body. But even if that is a plausible, if sophisticated, mental construct for an ape, the same sort of explanation is not going to be plausible for the lowly cleaner warasse. Perhaps, suggest some, it is an instinctual reaction – “seeing another fish with something on its belly may trigger rubbing behaviors in the fish looking in the mirror.” If that seems farfetched, it a lot less farfetched than positing self-awareness in a fish!
What hangs on this? If (as most philosophers think) self-awareness implies moral standing and one of the lessons of racism is that moral standing does not come in degrees. You either have it or you don't. And if you do, you deserve equal treatment - and that includes the cleaner warasse if it really is self-aware.