An octopus has nine brains: one central brain and a mini-brain in each of its eight arms.

Octopuses possess a highly complex nervous system containing roughly 500 million neurons. Unlike humans, where most neurons are in the brain, about two-thirds of an octopus's neurons are located in its arms. Each arm contains a cluster of nerve cells called a ganglion, which acts as a local control center for that specific limb.Research published in journals like Current Biology has shown that these arm brains can process sensory information and execute motor commands autonomously. For example, a severed octopus arm can still react to stimuli, such as grasping food or withdrawing from pain, for several hours after being detached. This unique architecture allows the central brain to focus on high-level tasks like navigation and problem-solving.The central brain communicates with the arm ganglia through a massive network of nerve fibers, but it does not need to micromanage every movement. This 'embodied intelligence' is a major focus of study for researchers at institutions like the Hebrew University of Jerusalem. By delegating tasks to the arms, the octopus can manage complex, simultaneous actions that would overwhelm a centralized nervous system.This evolutionary adaptation is essential for a soft-bodied predator that must constantly monitor its environment while manipulating objects. The ability to taste through suckers and move each arm independently provides a significant advantage in hunting and survival. Scientists are currently using this biological model to develop soft robotics that can function without a central processor.