Anna Hartz
This small fish shows self-awareness like apes.
Animals have surprised scientists with their intelligence for decades. From chimpanzees to dolphins, many species have shown they can recognize themselves. Now, a small fish called the cleaner wrasse, or Labroides dimidiatus, has joined that list.
It passed the mirror test
A new study published in Scientific Reports shows that this little fish can pass the mirror test, a standard experiment used to measure self-awareness in animals. The test usually involves placing a mark on the animal’s body and seeing if it reacts to its reflection, writes Videnskab, as if noticing something unusual on itself. Chimpanzees, elephants, and dolphins are some of the few species that have passed it. Now the cleaner wrasse appears to do the same.
In most studies, animals see a mirror before the mark is placed on their body. This study did the opposite. The researchers first marked the fish with a small, parasite-like spot and only then introduced the mirror. Shumpei Sogawa, a behavioral scientist at Osaka Metropolitan University in Japan, explained that the fish were likely aware that something was unusual on their bodies but could not see it.
The researchers were surprised at how quickly the fish reacted. On average, they tried to rub off the mark within 82 minutes, even before seeing their reflection. When the mirror was introduced, the fish immediately matched what they saw with the mark on their bodies.
Self-awareness in animals
After several days of mirror exposure, the fish showed even more remarkable behavior. Some picked up a tiny piece of shrimp from the bottom of the tank, carried it to the mirror, and then dropped it while watching the reflection. They followed the movement of the shrimp in the mirror closely and touched the mirror with their mouths.
The study suggests that self-awareness may have developed at least 450 million years ago. It also raises the possibility that this ability is more widespread among vertebrates, animals with a backbone, than previously thought. The cleaner wrasse’s actions demonstrate that intelligence and self-recognition can exist in creatures much smaller and simpler than mammals or birds.
These findings challenge our ideas about what it means to be aware of oneself. Even tiny fish, often overlooked in studies of cognition, may possess a surprising level of intelligence.
