The Nine Brains of the Octopus
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The Nine Brains of the Octopus

By Navya Arora

Have you ever wondered what it would be like to have multiple brains? The answer to this question may lie within a rather familiar animal. 

The octopus has not one, but nine brains and is considered to be one of the most intelligent animals on Earth. The brain to body ratio for octopuses is the largest for any invertebrate and they have about the same amount of neurons as a dog. Unlike humans, who have a centralized nervous system consisting of a single brain sending signals to the rest of the body, octopuses have decentralized nervous systems. They have one central brain in their head, and the base of each of their arms contains a group of neurons which can each function as their own “mini brains.” About ⅔ of an octopus’ 500 million neurons can be found outside of their central brain, meaning each of the arms contains around 40 million neurons, which is more than frogs have in their entire bodies. This allows each of the arms to be able to think and function independently. 

The larger, central brain located in the head of the octopus determines what it wants or needs, and sends commands to the arms. For example, if the central brain decides that the octopus needs food, it communicates with the arms and commands them to look for food. Each arm is autonomous and can make its own low-level decisions without “consulting” with the larger central brain. The arms can each move independently, gathering and processing their own sensory information. The arms will then report back any relevant information such as the location of the food to the central brain, which will continue making the bigger decisions. Even cooler, if you were to chop off an octopus arm, it would still be capable of moving independently for some time. A group of scientists showed that when an arm was disconnected from an octopus and was electrically stimulated it would still move in the same basic patterns as it normally would if it were connected to the octopus, and could even adapt its movements to different environments just as a connected arm would. This implies that each arm is indeed independent of the rest of the body and can likely think on its own. 

Overall, the octopus is one of the smartest and unique creatures, being able to escape from tanks and jars, and even cooperate with fish to hunt together, which scientists say is an ability that is very rare among animals. Since octopuses don’t have many physical protections, such as an exoskeleton or a spine, many believe that it is their intelligence which keeps them alive.


Bradford, N. (2023, March 1). How Octopus Arms Bypass the Brain. Scientific American.

Golembiewski, K. (2022, December 12). Are Octopus Smart? A Look Inside the Brain of an Octopus. Discover Magazine.

Maxwell, A. (2022, October 5). Nine Brains, Three Hearts and Other Octopus Anatomy Facts. Northrop Grumman.

National Marine Aquarium. (n.d.). Octopuses. Ocean Conservation Trust.

Stephen, M. (2021, April 7). Nine Brains Are Better Than One: An Octopus’ Nervous System | Biomechanics in the Wild. Notre Dame Sites.

Ward, D. (2020, September 29). Octopuses: 8 Arms, 9 Brains | Vanderbilt Student Volunteers for Science. Student Org | Vanderbilt University.

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