The octopus isn’t the first animal that comes to mind when most people think of intelligent animals. That may make sense given that octopi are classified are invertebrates and belong to the mollusk family. In fact, there are some mollusks that do not have brains at all, such as the clam.
To say that Octopi are intelligent animals requires some definition of what is meant by “intelligence.” Well, they are capable of having emotions, displaying individual personalities, playing with toys, and can even form relationships with people.
These traits are rare among animals, being that only a few species have those abilities to any great extent. Chimpanzees are one example, but that’s hardly unexpected, since they are closely related to humans. In contrast, Octopi are not at all closely related to human beings.
An octopus has a brain about the size of a walnut, which is the largest brain of any invertebrate. It contains an estimated 130 million neurons. Though many are stored in the arms, they are a good indicator of an animal’s intelligence.
Researchers are aware that we cannot know with complete certainty how various animals perceive the world, but we are discovering new things all the time that we never expected.