Octopuses can learn to read a mirror's reflection to locate food they cannot directly see, according to a Dartmouth study published in Current Biology. Researchers trained three California two-spot octopuses to ignore a crab image appearing in a mirror and instead move to where the hidden stimulus was actually positioned behind them. The animals reached the correct side roughly 73% of the time.
Lead author Mary Kieseler, who ran the work in Dartmouth's Octopus Lab and is now a postdoctoral researcher at the University of Fribourg in Switzerland, said the results are the first to show an invertebrate using a mirror to understand its surroundings and find prey. Until now, that kind of mirror-guided spatial reasoning had been documented only in vertebrates such as some mammals and birds.
The team stresses the octopuses were using mirrors as a tool to locate occluded objects, not recognizing themselves. Still, linking a visible reflection to a hidden location is a sophisticated form of mediated perception that some scientists view as a building block toward self-recognition, adding to a growing body of evidence for the cephalopod's surprising intelligence.