A very smart fish
A tiny fish has joined an elite group of animals that can recognize themselves in the mirror. Until now, the only species to have passed the mirror test—widely considered the gold standard for animal intelligence—were great apes, bottlenose dolphins, killer whales, Eurasian magpies, and a single Asian elephant. But to that list can now be added the cleaner wrasse, a 4-inch striped fish that lives in coral reefs. For the mirror test, scientists in Germany placed a mark on the fish in a place that could only be seen in a mirror. After initially seeming confused by the mirror, the cleaner wrasse appeared to check their reflection multiple times, and tried to remove the mark by rubbing their bodies on hard surfaces. The fish didn’t act the same way in control experiments with no mirror, or when the mark was placed on the mirror. Co-author Alex Jordan tells The Daily Telegraph (U.K.) that the fish “behaviorally fulfills all criteria of the mirror test.” He says the species is either self-aware or the “gold standard” test needs updating.