Researchers at Dartmouth have shown that octopuses can learn to use mirrors to find food they cannot see directly. The study, published in Current Biology, marks the first time this ability has been documented in invertebrates.
The team trained three California two-spot octopuses at Dartmouth's Octopus Lab. After familiarizing the animals with a mirror, researchers placed a virtual crab image behind each octopus so it was visible only in the reflection. The octopuses had to turn and move toward the actual location to receive a reward. The animals chose the correct side about 73 percent of the time. Lead author Mary Kieseler said the findings demonstrate that invertebrates can use mirrors to understand their environment and find prey, a skill previously seen only in some mammals and birds. Senior author Peter Tse noted that octopuses learn to interpret reflections much like humans learn to use a rearview mirror. The results suggest these animals may maintain an internal map of space, which could aid their hunting strategy in complex environments such as coral reefs. Kieseler added that the last common ancestor of octopuses and humans lived 350 to 500 million years ago, pointing to possible convergent evolution in cognitive abilities.