Like humans, octopuses can fall for the rubber hand illusion and believe that a fake arm is theirs. This suggests they have a sense of their own body, just as we do.

The rubber hand illusion is a bizarre multisensory trick where people start believing a fake hand is their own. It involves hiding a person’s real hand behind a screen and placing a fake one in front of them on a table, and then stroking both simultaneously.

The illusion was first demonstrated by Matthew Botvinick and Jonathan Cohen in 1998, and it was later shown that monkeys and mice also fall for the same trick.

The research shows that even invertebrates, whose brains are vastly different from ours, also possess a sense of body ownership similar to humans. Studying these creatures could therefore tell us more about this key component of self-perception.