Science and the Sea podcast

Download our free app to listen on your phone

Download on the App StoreGet it on Google Play

We might not always think so, but people who spend time preening in a mirror are actually passing an intelligence test -- showing an awareness that the thing in the mirror is them. Only a few other species have shown this level of self-awareness, including dolphins and elephants. The most recent addition to the list is a fish that was already known to be pretty smart. The cleaner wrasse is found on coral reefs from the east coast of Africa to Hawaii. It’s only a few inches long, and it has multiple stripes. It gets its name because it cleans parasites off of other fish. A wrasse typically stakes out a station on the reef, and waits for “clients” to come to it. When a client is ready for a cleaning, it stops and waits for the wrasse to get to work. The cleaner wrasse was already known as a pretty smart critter. It can recognize many of its clients, and it knows which ones it can “cheat” on by nibbling on their flesh -- it plays things straight with predators, or when other clients are watching. A recent study added to their reputation. It found that wrasses appeared to identify themselves in mirrors. The test subjects first treated the image in the mirror as a possible competitor. They then performed unusual moves, such as flipping on their backs. Finally, they returned to the mirror often to check themselves out. And when researchers added a dark mark under the skin, they tried to rub it off on nearby rocks. So the fish used the mirror to keep tidy -- just like people.

More episodes from Science and the Sea podcast