Octopuses only have one true brain, which is located in their head, wrapped around their esophagus. However, octopuses have other neurons, the cells that form the brain, in other places as well. Octopuses have large numbers of neurons located near their eyes and others inside their arms.
According to Wired.com, octopuses have about 500 million neurons in total. Approximately two-thirds of these are located in the creatures' arms, with the rest split between the true brain and the cells that clump near the optic nerves. Scientists are trying to learn more about the brain and intelligence of octopuses because they are so distantly related to other intelligent animals, such as dolphins, dogs and humans.