Two-thirds of an octopus's neurons live in its arms
Each limb can touch, taste, and decide to hunt for food independently, essentially acting as a semi-autonomous creature that can occasionally argue with the central brain.
When an octopus explores a crevice, it is not always the central brain directing the search. About 350 million of the animal's 500 million neurons are located outside the head, woven into the tissue of its eight arms. This distributed architecture allows each limb to process sensory data and execute complex motor tasks, like unscrewing a jar or untying a knot, without waiting for instructions from the main processor. If an arm discovers an interesting texture or a potential meal, it can momentarily override the central brain’s commands, continuing to probe even as the rest of the body attempts to swim away.