Everything You Need To Know About An Octopus Brain! - OctoNation

An octopus has one central brain shaped like a donut around its esophagus. Each arm also contains dense neural circuitry (an axial nerve cord with many ganglia) that we call satellite brains. That’s why people say octopuses have “nine brains.” Each arm can sense, taste, and coordinate movement on its own, while the central brain handles bigger decisions. TLDR: An octopus runs on distributed intelligence, which helps explain their wild problem-solving skills, including opening child-resistant pill bottles in aquarium tests! 🤯

What Most People Get Wrong About “Nine Brains”

Most people hear “octopuses have nine brains” and picture nine separate mini brains. Here’s what they’re missing…

“Nine brains” does not mean nine separate minds.It’s one integrated nervous system with specialized control centers.

It’s not nine full brains.Octopuses have one central brain, and each arm contains dense neural circuitry (an axial nerve cord plus many ganglia) that can process touch, taste, and movement locally. We nickname this distributed arm network “satellite brains.”

The arms aren’t just muscle.About two-thirds of an octopus’s neurons are in its arms, so each arm can process touch, taste, and movement locally.

The central brain doesn’t micromanage every move.Octopus intelligence is distributed: the central brain sets direction, and arm circuits handle a lot of real time execution.

Quick aside: octopuses don’t just have a distributed nervous system, they also have a distributed circulation setup with three hearts. (If you want the full breakdown, read how many hearts an octopus has.)

Why Evolution Likely Favored a Networked Octopus Nervous System

An octopus does not run on one boss brain giving every tiny order.The brain calls the game plan (hunt! hide! explore!).Each arm handles lots of split second moves on its own (feel, grip, adjust).Think coach and players: the coach sets strategy, the players make real-time plays.

Can you imagine trying to run eight super flexible robot arms with one tiny joystick? Everything would bottleneck fast. Octopuses avoid that by letting each arm handle a lot of local sensing and control, while the central brain coordinates the big picture plan.

So in term of evolution, selection likely favored a hybrid setup:

• Local speed: arm circuits process touch, taste, and movement close to where it happens
• Central strategy: the brain integrates information and steers goal driven behavior
• High flexibility: arm level programs handle lots of real time movement detail
• Robust coordination: the system likely performs well in dynamic, unpredictable environments

Octopus intelligence isn’t only centralized in the brain. It’s a team effort shared across brain and arms!

What are neurons?

… A fancy way of saying nerve cells!

Most people think the brain does the thinking and the body just reports back.Octopuses are different: they use distributed processing. 🧠➡️🐙

A neuron is a nerve cell that sends and receives information using electrical signals (within circuits) and chemical signals (at synapses).

In humans, neurons build the nervous system’s communication grid:

• brain
• spinal cord
• peripheral nerves

Octopuses use the same building blocks, but they distribute much more local processing into their arms.

Think of it like this:A human nervous system is more centralized.An octopus nervous system is more networked, with arms handling lots of local sensing and control while the central brain coordinates the big picture.

Something as simple as picking up a cup requires our brain to send a message to the muscles in our hand and fingers to contract. Octopuses have this same neural network; however, it’s a little more spread out than ours.

This brings us to…

What are ganglia?

… Clusters of neurons spread throughout the body that can carry nerve signals to and from the central nervous system.

The octopus’ arm nervous system consists of:

• One main nerve “highway” (the axial nerve cord)
• Four muscle-control nerve cords
• A ganglion for each sucker, plus extra local ganglia along the arm

With these neural powers combined, octopus arms can perform some sensing and motor actions locally, while still coordinating with the central brain. Have you ever heard the fact that an octopus has 9 brains? We refer to the ganglia in each arm as a satellite brain communicating between each other. Cool right? 📡 🧠 We imagine that it’s really important that the central brain isn’t overwhelmed with the input from thousands of tasting, smelling, feeling, sensing super suckers. A better use of brain power would be keeping an eye out for predators and remembering where the best spots to eat are!

“The octopus’ arms have a neural ring that bypasses the brain, and so the arms can send information to each other without the brain being aware of it,” said behavioural neuroscientist Dominic Sivitilli of the University of Washington.

“So while the brain isn’t quite sure where the arms are in space, the arms know where each other are and this allows the arms to coordinate during actions like crawling.”

Talk about the ultimate multi-tasker!

Fun fact

The Common Octopus (Octopus vuglaris) has about 500 million neurons in its body which is around the same as a dog! We love callin’ em squishy puppy dogs! 🥰 They have come a long way from their mollusk cousins who, on average, have around 20,000 neurons.

So, how does an octopus brain work?

An octopus’s main brain sends commands to its ganglia like “search for food”. The arms will wiggle through crevices, contracting or relaxing the muscles, feeling, and tasting, determining whether it’s found a tasty treat or just an empty hole. This leaves the main brain looking out for predators.

When the arm has relevant information like locating food, it sends that information to the main brain who then determines what to do next.

Imagine telling your hand “look for food” and within minutes the thing you were craving appears in front of your face without giving it a second thought!

Unfortunately, we are lacking fingertips that can taste and smell food (hello MAGICAL OCTOPUS SUCKERS that can each contain up to 10,000 specialized neurons) so we are forced to use a decent amount of brain power to figure out a meal.

Imagine if the tables were turned and octopuses were studying us! How basic would we seem if the only thing our hands can do is grasp stuff?

Octopus have a donut-shaped brain!

An octopus’s brain is located right between its eyes and is the shape of a donut.

Stay with me because it gets even weirder… their esophagus passes THROUGH their brain!

Every time they eat, they risk severe brain damage if their meal isn’t well and truly chewed up! Luckily they accomplish this by slicing up their prey with their serrated radula plus breaking down their meal with enzymes in their saliva.

Are octopuses smart?

In a word: YES!

How do we know? A sign of intelligence is learning new tasks and committing events to short and long-term memory. Smarter animals also tend to have a high brain-to-body ratio, however; studies involving intelligence in birds (and their tiny bird brains) have shown this isn’t as definitive as it used to be.

Animals have evolved all sorts of interesting brains and unique nervous systems that the brain-to-body ratio has become an outdated metric.

Octopus Can Learn!

In aquarium settings, they have learned to solve puzzles, navigate mazes, and unscrew jars to get to food rewards.

In the wild, they use tools. The Veined Octopus literally carries around coconut husks and empty shells, using them as portable shelters or shields. Their 8 arms allow them to carry their coconut AND wander along the bottom of the ocean floor in an awkward stilted walk.

Another fast learner is the one and only Mimic Octopus! It can transform itself into different animal species like lionfish, sea snakes, flounders and tunicates, expertly tricking its predators.

What’s even more impressive is that the Mimic Octopus chooses how to reinvent itself based on its predator. Scientists observed this when a damselfish started attacking a Mimic Octopus who chose to turn itself into a banded sea snake, a known predator of the damselfish.

🐙 Octopus Fun Fact

It’s not just octopuses who are cephalopod smarty pants. Cuttlefish have been shown to pass basic tests delaying gratification, which some human toddlers have trouble passing.

They’re mischievous!

They pull wild antics that have been well documented in aquarium settings where octopuses will get up to mischief.

There have been multiple reports of fish going “missing” at aquariums that also have a resident octopus. When cameras are installed, the octopus is seen crawling over to a fish tank, having a snack, and then heading back to its tank as if nothing ever happened.

🐙 Octopus Fun Fact

An octopus held at the University of Otago in New Zealand had to be released after it figured out that squirting jets of water at light bulbs would short-circuit the entire power supply.

Octopus Can Remember People!

A research study on Giant Pacific Octopuses at the Seattle Aquarium showed that their behavior, breathing, and colors changed depending on whose face they recognized.

Eight different GPOs were treated either by a ‘nice’ keeper who gave them food or by a designated ‘mean’ keeper who poked them with a bristly stick. After just two weeks of this test, the octopuses would approach the nice keeper but hid away when the mean keeper came around.

Measuring “smartness” is tricky. It’s not like you can sit an octopus down and take an IQ test. And what if they had test anxiety!?! Speaking of, we asked researcher Dr. Alex Schnell “How Do You Measure the IQ of an Octopus?” She answered here in this blog!

Animals can be smart in different ways considering we are all adapted to our surroundings.

As Einstein said, “Everybody is a genius. But if you judge a fish by its ability to climb a tree, it will live its whole life believing it is stupid.”

Octopus Brain FAQ

🔍 How many brains does an octopus have?

Nine. One central brain and eight mini-brains (satellite-brains) in each arm. This decentralized intelligence lets each arm “think” on its own—grabbing food, navigating the substrate, and even resisting detachment reflexes if severed.

🧪 Are octopuses really intelligent?

Absolutely. They can open jars, escape mazes, solve puzzles, and recognize humans. Some even engage in play—chasing objects or making “toys” out of shells.

And science is starting to catch up. A 2023 study published in Science Advances found that octopuses have a bunch of unique genetic switches—called microRNAs—that are mostly found in their brains and during development. Basically, their nervous system is wired in a way that’s totally different from most animals… and may help explain why they’re so freakishly smart. We wrote a blog all about how Octopus can edit their own RNA!

🧠 Why is their main brain shaped like a donut?

The esophagus passes straight through the octopus’s brain—literally. If they swallow something too big? It could damage the brain!

🕹️ What can their arm brains do?

Each arm’s nervous system can perform reflexes, adjust grip, and explore environments without needing constant input from the main brain. It’s like giving each arm a semi-autonomous operating system. 👾

According to a 2022 article in Frontiers in Systems Neuroscience, octopus arms contain the majority of the animal’s neurons and can function independently, continuing to respond to touch even after separation from the body.

🧬 Can octopuses learn?

Yes—and not just by trial and error. Studies show octopuses can learn by observation (social learning), have short- and long-term memory, and show problem-solving that rivals birds and mammals.

One classic 1992 experiment published in Science demonstrated that untrained octopuses learned to select the correct object after observing trained peers complete the task—providing compelling evidence of observational learning.

📚 Further Reading:

Wanna go deeper? Check out:

• How Smart Are Octopuses?
• How Do You Measure the IQ of an Octopus?
• Dreaming Octopus: Are They Having Nightmares?
• Octopus can edit their RNA – Here’s How…

If you want to educate yourself some more about all sorts of different cephalopods, take a look at our encyclopedia. Or, what we call it, our Octopedia!

Connect with other octopus lovers via the OctoNation Facebook group, OctopusFanClub.com! Make sure to follow us on Facebook and Instagram to keep up to date with the conservation, education, and ongoing research of cephalopods.

More Posts To Read:

• Meet the Cockeyed Squid: the Deep-Sea Animal with a Giant Eye!
• 10 Facts About Baby Nautilus!
• Does Octlantis Exist?
• Dumbfounding Flapjack Octopus Facts You NEED To Know!
• What Is The World’s Biggest Octopus?

Corinne Klein

Corinne is a biologist with 10 years of experience in the fields of marine and wildlife biology. She has a Master’s degree in marine science from the University of Auckland and throughout her career has worked on multiple international marine conservation projects as an environmental consultant. She is an avid scuba diver, underwater photographer, and loves to share random facts about sea creatures with anyone who will listen. Based in Japan, Corinne currently works in medical research and scientific freelance writing!