Imagine walking along the ocean floor and spotting what looks like an ordinary rock. You swim a little closer, and suddenly the “rock” grows eight arms and disappears into a crack. It was an octopus all along. Octopuses are masters of disguise, capable of changing the color, pattern, and even texture of their skin to blend into their surroundings.
But camouflage is only the beginning of what makes these animals extraordinary. They can solve puzzles, manipulate objects, learn from experience, and coordinate eight flexible arms with a nervous system unlike our own. The more scientists study them, the more complicated one question becomes: What does it actually mean to be intelligent?
An octopus does not need a costume closet. Its skin is the costume. Specialized structures called chromatophores contain sacs of pigment that expand and contract under muscular control. By activating different combinations of these structures, an octopus can create changing patterns of spots, stripes, and colors. It can also alter the texture of its skin, making its body appear rough like a rock or uneven like coral.
According to a 2023 review, “Neural Control of Cephalopod Camouflage,” these changes are controlled by an intricate connection between the nervous system and the skin. There is an even stranger twist: octopuses are generally thought to have only one type of visual pigment, unlike humans, who use three types to distinguish colors. Yet they can still produce camouflage patterns that closely resemble their surroundings.
A 2022 study, “The Colours of Octopus: Using Spectral Data to Measure Octopus Camouflage,” examined how octopuses match their environments despite this unusual visual system. Scientists are still investigating exactly how they achieve such effective camouflage, but their abilities already challenge the assumption that an animal must see the world as humans do to respond to it in remarkable ways.
Their nervous system is just as unusual as their skin. An octopus has a central brain, but much of its nervous system is distributed throughout its body. A large proportion of its neurons are located in its arms, which contain networks of nerve cells and sensory receptors that help them respond to touch, chemicals, and movement.
This means an arm can process a surprising amount of information without waiting for the brain to direct every action. Researchers explored this arrangement in a 2020 study, “Use of Peripheral Sensory Information for Central Nervous Control of Arm Movement by Octopus vulgaris.” Their findings showed how information gathered by the arms contributes to the control of movement. Instead of relying on one central command center for every detail, an octopus coordinates a nervous system in which the brain and arms share the work. Imagine trying to tie your shoes while each hand independently responds to its surroundings. For an octopus, coordinating eight flexible arms is part of everyday life. This arrangement also raises a fascinating question: if so much information is processed outside the central brain, where exactly does an octopus’s intelligence happen?
Intelligence, however, is not just about having a complicated nervous system. It is also about what an animal can do with it. In a 2016 experiment published in PLOS ONE, researchers tested seven common octopuses using a container puzzle. The animals had to retrieve food from an L-shaped container by pulling or pushing it through an opening.
As the experiment progressed, researchers changed the task by altering the container’s orientation, adding an opaque barrier, and making its starting position less predictable. The octopuses learned to complete the different stages, demonstrating an ability to adjust their behavior when familiar situations changed. The study, “Pull or Push? Octopuses Solve a Puzzle Problem,” offers evidence of behavioral flexibility, an important ability in problem-solving. Octopuses have also demonstrated a behavior that might look surprisingly familiar to anyone who has ever packed a bag before leaving home. In 2009, researchers Julian Finn, Tom Tregenza, and Mark Norman observed veined octopuses collecting discarded coconut shell halves and carrying them across the ocean floor.
The shells offered little protection while being transported, but the octopuses later assembled them into shelters when needed. Published in Current Biology, “Defensive Tool Use in a Coconut-Carrying Octopus,” documented an example of an invertebrate collecting and carrying objects for later use. Carrying around something that might become useful later sounds familiar, but for an octopus, it is an impressive survival strategy.
Even more surprisingly, octopuses may be able to learn by watching others. In a 1992 study published in Science, researchers Graziano Fiorito and Pietro Scotto investigated whether common octopuses could learn by observing other octopuses. Untrained animals watched trained demonstrators choose between two objects. When the observers were later tested on their own, they tended to choose the same object as the octopus they had watched. The researchers reported that these animals learned the task more quickly than animals that learned through individual conditioning. Their findings, published in “Observational Learning in Octopus vulgaris,” suggested that observational learning could occur in an invertebrate. Although one experiment cannot establish exactly how octopuses understand what they observe, it adds another intriguing possibility to the study of their intelligence.
It is tempting to measure every animal’s intelligence using human abilities: language, memory, tool use, or problem-solving. But octopuses evolved along a very different path. Their ancestors were mollusks, and their nervous systems developed independently from those of vertebrates. A 2023 review, “Evolution of Cephalopod Nervous Systems,” explores how complex nervous systems evolved in cephalopods through a separate evolutionary history. That difference matters. An octopus does not need to think like a human to solve problems, explore its environment, or respond flexibly to new situations.
Researchers still debate how much of its behavior reflects complex reasoning rather than learning through repeated experience. A review titled “How Intelligent Is a Cephalopod? Lessons From Comparative Cognition” emphasizes the importance of studying these abilities carefully instead of assuming that impressive behavior automatically proves humanlike thought. Perhaps the most interesting thing about an octopus is not that it resembles us. It is that it gives us a reason to question what intelligence can look like in the first place. Its skin can become a disguise, its arms can process information, and its behavior can adapt to problems that have never appeared in quite the same way before. Somewhere beneath the waves, an animal with no backbone, no hands, and a very different kind of brain is quietly challenging our definition of a thinking mind.
