Biology First evidence in invertebrates: octopuses understand mirror images
Octopuses can understand mirror images. A research team at the University of Freiburg has taught three octopuses to use a mirror to locate and navigate to food outside their field of vision.
03.06.2026, 17:00
SDA
The study, published on Wednesday in the journal "Current Biology", provides the first evidence of the ability to use mirrors in an invertebrate. Previously, this behavior was only known from vertebrates such as monkeys, elephants or birds.
For the experiment, the researchers from Dartmouth College (USA) and the University of Fribourg (Switzerland) placed three squid of the species "Octopus bimaculoides" individually in a starting container within an aquarium. From this container, the animals could only see a virtual crab as a reflection in an opposite mirror.
The direct view of the projection of the crab was blocked by the walls of the container. To receive a real crab as a reward, the octopuses had to leave the container and move to the side of the back wall where the virtual crab was projected instead of swimming to the mirror.
High success rate in the test
The octopuses mastered the task promptly: in 73 percent of the test runs, they chose the correct path - statistically significantly above chance. With increasing experience, they reached their destination faster and faster.
In some cases, the animals even climbed directly over the side walls of the starting container. In other words, they deliberately moved away from the tempting mirror image in order to reach the blocked prey directly. According to the researchers, this not only proves that the animals can suppress the impulse of a direct attack on a visual stimulus, but also that they link the mirror information with an internal 3D map of the pool
The proof of this ability in octopuses is particularly significant from an evolutionary perspective: the last common ancestor of vertebrates and cephalopods, to which octopuses belong, lived over 520 million years ago. Since then, the brains of the two groups have developed completely independently of each other.
The fact that octopuses now show the same ability to use mirrors as some highly developed vertebrates suggests that nature has independently produced the same clever solution to spatial navigation problems.
