Written by: Lacey Bishop-Schouster
Edited by: Courtney Myers
This piece was written in collaboration with the 2025 ComSciCon-MI Write-A-Thon.
When we think about intelligence in the animal kingdom, our minds often go straight to ourselves. Then maybe to apes cracking nuts with tools, dolphins playing games, or elephants who “never forget.”
However, there’s another group of animals that is often overlooked and should be included with these examples: the cephalopods. Cephalopods—octopuses, squids, cuttlefish, and nautiluses—are a class of mollusks distinguished by their soft bodies, tentacles, and ability to move by jet propulsion. Although they are invertebrates, they show some of the most complex behaviors on the planet. In fact, they have the largest brains of any invertebrates, and their path to intelligence looks nothing like ours.
Cephalopods pack around 500 million neurons, rivaling neuron counts of many reptiles and fish and approaching those of small mammals. What makes cephalopods especially fascinating is not just the number of neurons, but how they are arranged. Instead of being concentrated only in the head, a large portion of these neurons resides in the nervous system that runs through the arms. In a sense, each arm can think for itself, allowing octopuses and squids to perform incredibly precise movements. Imagine having eight partially independent “mini-brains” in your arms working alongside your main one: that’s how an octopus can juggle hunting, camouflaging, and exploring all at once.
Their intelligence reveals itself in surprising ways. Some octopuses use tools, which is something we usually associate with certain mammal groups like humans and chimps. For example, the veined octopus has been known to carry coconut shells across the seafloor and assemble them into a portable shelter. Similarly, the blanket octopus has been seen ripping off the stinging tentacles of Portuguese Man o’ War jellyfish and wielding them against potential predators.
In captivity, octopuses have astonished scientists with their problem-solving skills. They can open latched boxes, navigate mazes, and even unscrew lids to reach hidden food. Some have taken it a step further by staging daring escapes. At the Bermuda Aquarium, for instance, an octopus was discovered sneaking out of its tank at night, raiding nearby enclosures for crabs and shellfish, and then slipping back into its own tank before morning. The staff eventually decided that their octopuses were simply too clever and now rotate individuals regularly to prevent repeat heists. Stories like this suggest that cephalopods have advanced intelligence skills, like memory and forethought.
Octopuses are also known for their sharp vision and memory. Aquarium keepers often report that they recognize individual humans and react differently to each one. Some become friendly with particular caretakers while squirting water at those they dislike. Their visual intelligence allows for other remarkable skills, like camouflage. Many species can instantly change their skin color and texture to blend in with their surroundings. This is not just a reflex. It requires the animal to assess its environment, compare patterns, and choose the best disguise. Some species even take mimicry a step further, impersonating dangerous animals like lionfish or sea snakes to trick predators.
Cephalopods are not only intelligent, but are also socially isolated animals, which contradicts many notions we have about intelligence. Unlike humans, apes, or dolphins, they don’t rely on group living to survive. Most species are solitary, and many are semelparous, which means they die shortly after reproducing, leaving no opportunity for parental care. After hatching, young cephalopods drift off on their own, navigating life without guidance. By the social brain hypothesis— which suggests intelligence evolves to handle the complexities of group life— cephalopods shouldn’t be this smart. And yet they are.
This forces us to rethink what intelligence really is. Perhaps intelligence does not belong only to social species, or even to creatures with skeletons and familiar body plans. Cephalopods show us a convergent path with minds that evolved in the ocean’s depths, shaped by different pressures than ours. Their survival depends on creativity, problem-solving, and adaptability, not cooperation.
That’s what makes them so captivating! Cephalopods remind us that there isn’t just one way for intelligence to evolve. Their bizarre mode of intelligence demonstrates that the story of minds on Earth is far broader and more creative than we often imagine. If intelligence can arise in such a strange and solitary lineage, who knows where else intelligence may lie in the animal kingdom?
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