Octopus opening a container
with a screw cap Octopuses are widely recognized as the most intelligent of all invertebrates (animals without backbones). They are among the most intelligent animals overall’ says Christopher Whalen, an American Museum of Natural History paleontologist. They are capable of tool use and problem-solving. Studies have showed they have the most centralized nervous system of any invertebrate and possess exceptional learning abilities, including spatial and social learning, as well as problem-solving capabilities.
Octopuses and other cephalopods have long been studied because of their intelligence. The animals possess remarkable memories and are curious about their surroundings. In the the third century A.D., Roman author and naturalist, Claidius Aelianus, observed their "plainly seen" characteristics of "mischief and craft." Octopuses can solve complex puzzles, navigate mazes and show a preference for different individuals. They display many cognitive, behavioral and affective traits once regarded as the sole domain of higher vertebrates.
Octopuses can learn after very little trial and error. Experiments have shown that octopuses who watches another do an unfamiliar task can learn to do themselves. They are the only invertebrate observed doing this which is seen as precursor to conceptual thought.They can open a jar and take out a fish and reach inside a wine bottle to remove a cork. They have been seen barricading their den with stones, and squirting jets of water to deter predators and short circuit aquarium lights. There is also evidence they have distinct personalities, recognize individuals, and express emotions by changing color.
Relative to their size, octopuses have larger brains than most animals other than birds and mammals. They can make determination based on visual, tactile, and chemical cues. Aquarium staff have reported catching naughty octopuses leaving their tanks to steal food from neighboring tanks. An analysis of underwater images suggests octopuses are increasingly using discarded bottles, cans, and other human rubbish as shelter or as a sanctuary for their eggs. According to Yale Environment 360: The research, published in Marine Pollution Bulletin, documented 24 species of octopus sheltering inside glass bottles, cans, and even an old battery; burying themselves under a mixture of bottle tops and seashells; even carrying plastic items around while “stilt-walking” on two tentacles to conceal themselves from predators. [National Geographic, Geographica, December 1992; Yale Environment 360, March 11, 2022]
Roland Andersen of Seattle’s Aquarium told National Geographic octopus have spit in the face of scientists, blocked their dens with rocks, shot water at plastic bottle targets (and at lab staff to amuse themselves), slipped out of their tanks to enter the tanks of fish to eat them, and dismantled pumps and blocked drains. When people pet octopuses, the octopuses sometimes pet back. Octopuses display play behavior, such as repeatedly placing bottles in tank currents and watching them float past, and displaying different temperaments such as aggression (attacking a crab as soon as they saw it), passivity (taking their time to move on the crab), and paranoia (shooting out ink when presented with a crab).
Websites and Resources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Fishbase fishbase.se ; Encyclopedia of Life eol.org ; Smithsonian Oceans Portal ocean.si.edu/ocean-life-ecosystems
Octopus Using Their Intelligence to Fend Off Predators
The main predators of octopuses are large fish, moray eels, some whales, seals,, dolphins and sharks. Their main antipredator adaptation is the ability to camouflage themselves. There are five mechanisms in this category: 1) camouflaging into any background, 2) countershading, 3) mimicry (mimicking a venomous fish), , 4) changing their appearance into different things, 5) controlled ability to change their phenotypes (observable characteristics). Octopuses can spot predators from around eight meters away. Once spotted, octopuses will either camouflage themselves or hide in their dens. They also can squirt ink. Ink may blind a predator and inhibit it sense of smell, allowing the octopus to escape. [Source: Heidi Chicas, Animal Diversity Web (ADW) /=]
Octopuses employ a range of behaviors for concealment and defense. They can change shape from flattened, formless blob to a threatening, upright posture if a predator is detected. Color changing is not the only way they they camouflaging themselves. Other behaviors designed to disrupt the coherence of the body's outline and make them hard to see include changing the shape of the mantle, twisting or waving arms, and erecting papillae that alter the animals texture and appearance. [Source: Kelly Ray /=]
In December 2009, scientists at Melbourne’s Victoria Museum released a photograph of an octopus with its legs wrapped around a coconut shell, which it used to protect itself on the sea floor. The scientists said the octopus carries the shell with it and uses it as armor in what the scientists said was the first known example of an invertebrate using tools.
Describing an octopus defending itself in a pretty sophisticated manner, Ed Yong wrote in The Atlantic: “A small shark spots its prey — a meaty, seemingly defenseless octopus. The shark ambushes, and then, in one of the most astonishing sequences in the series Blue Planet II, the octopus escapes. First, it shoves one of its arms into the predator’s vulnerable gills. Once released, it moves to protect itself — it grabs discarded seashells and swiftly arranges them into a defensive dome.[Source: Ed Yong, The Atlantic, July 2, 2019] .
Octopus Using Its Intelligence to Open a Clam Shell
Octopus in a shell Jennifer A. Mather wrote in Natural History magazine After capturing a clam, an octopus must break through the hard shell to get to the meat inside. To do so, it can deploy a veritable built-in Swiss Army knife of tools . It can pull the shell's halves apart with its arms and suckers, chip at the shell's edge with its beak, or drill a tiny hole in the shell by alternately secreting acid to dissolve it and scraping at it with one of two tooth-covered organs in its mouth. [Source: Jennifer A. Mather, Natural History, February 2007]
Giant pacific octopuses usually drill through the center of a clam's shell into its heart. But they must learn where to drill the holes. Anderson found that juveniles drill their first few holes randomly on the shell, but they soon master the art of drilling near the heart or the muscles that hold the shell halves together. Either place is a good target for injecting paralytic toxin.
We were curious about what octopuses would do with artificially strong Manila clams, whose shells they usually just pull apart. We gave each octopus Manila clams held together with strong wire. The octopuses simply switched tactics to drilling or chipping, thereby confirming the numerous studies such as Muntz's that had shown they are good problem-solvers. They can weigh effort against food reward, flexibly switch penetration tactics, and orient the clam to penetrate its shell most effectively — all good uses of intelligence, indeed.
Scientists Find Never-Before-Seen Brain Wave in an Octopus
In March 2023, scientists announced they had found octopuses possess a brain wave that has never been seen before in animals, along with others similar to those found in humans; Live Science reported: The groundbreaking study captured the first ever brain recordings of freely moving octopuses and was performed by implanting electrodes in the animals’ brains and connecting them to data loggers under their skin. The recordings have given scientists the very first inklings into the workings of cephalopod minds. The researchers published their findings March 27, 2023 in the journal Cell. [Source: Ben Turner, Live Science, April 28, 2023]
"Some of these activity patterns have some similarity to activity patterns observed in the mammalian hippocampus, also a memory center," first-author Tamar Gutnick, a visiting scientist at the University of Naples, told Live Science. "But we also observed unique patterns, 2Hz activity, that were never reported in other animals."
Octopuses and other cephalopods have long been studied because of their intelligence. However, octopuses’ minds can be difficult to peer into. The creatures’ arms can reach to any part of their boneless bodies, so not only can they easily snatch and detach any invasive tracking object, but there is no obvious place in which to anchor recording devices that can detect brain waves.
To get around this, the researchers surgically inserted medical tracking devices into the heads of three captive octopuses, placing lightweight data loggers often used on birds between their eyes before connecting them to electrodes inserted into a region of the octopuses’ brains responsible for learning and memory. The scientists then recorded the octopuses for 12 hours as the creatures slept, groomed themselves and explored their tank.
The recorded brain wave patterns surprised the scientists in a number of ways. First of all, the researchers discovered brain waves that were very similar to those found in the human hippocampus. This hints at convergent neurological evolution — where two separate animals evolve the same trait independently of each other — as humans’ last common ancestor with octopuses was a seafloor-trawling flatworm that lived around 750 million years ago and did not possess anything other than a rudimentary brain. The researchers also found brain waves known for controlling sleep-wake cycles in other animals.
Alongside the more familiar brain waves, the researchers also found ones they had never seen before in the recordings; long-lasting and slow, they repeated just twice every second. Scientists aren’t sure what these mysterious brain waves are being used for, and it will take more recordings while octopuses complete set tasks to fully map them, the researchers said. "Most likely they all require recordings on octopuses that are trained to show certain behaviors, so that we can get several repetitions with similar behavior," Gutnick said. "In vertebrates, this is the key to finding patterns in brain activity that help us to understand how the brain coordinates behavior."
Later Jennifer A. Mather and her colleagues turned their attention to play, which is associated with intelligence. She wrote in Natural History magazine, ..Would an octopus play if given the chance? We decided to find out. Animals are more likely to play when they are satiated and secure, without any threat from predators. An aquarium tank is such an environment. There we presented eight well-fed giant Pacific octopuses with plastic pill bottles containing enough water that they floated at the surface of the tank. The octopuses followed a fairly predictable behavioral sequence. First, they grasped a pill bottle with one or more of their arms and explored it with their suckers. Then they pulled it to their mouths, and sometimes bit it with their parrotlike beaks. Gradually, both within each trial, and by the end of all ten trials, most of them lost interest in the bottle. [Source: Jennifer A. Mather, Natural History, February 2007]
But two of the octopuses independently did something very different in the later trials. Like most aquariums, their tanks had water-circulation systems; water entered the tank at one end and exited at the other. While sitting near the outflow, each animal released the bottle it had been holding and jetted water through its funnel, sending the bottle against the gentle current to the inflow end of its tank. (A funnel is a tubelike appendage that an octopus uses for breathing and for jetting through the water [see photograph on pages 30-31].) When the bottles returned on the current, the octopuses jetted them upstream again, repeating the process more than twenty times. Anderson, who had been skeptical that octopuses play, phoned me excitedly after watching the first playful octopus and said, "It's like she's bouncing a ball!"
In vertebrates, some kinds of play have benefits as well as simply being fun. They strengthen and define social relationships, as in the roughhousing of canines. Or they give young animals the chance to hone fragmentary actions into polished sequences, as when a kitten plays with a mouse to "practice" capturing prey in the future. Skeptics often dismiss play by nonhuman animals as functional, and thus in violation of Burghardt's definition that it have no obvious purpose.
But octopuses don't have social relationships — they're solitary creatures, except when they mate. And as for the argument that only the young play because only they need to practice their skills, Michael J. Kuba, a former graduate student of mine now at Hebrew University in Jerusalem, recently showed that adult common octopuses also engage in playlike behavior. They passed a plastic block from arm to arm or pulled it along when they swam just as often as the young did. Still, in our view, octopus play is neither as extensive as it is in mammals, nor as potentially adaptive. It may simply be a sign of an active mind at work.
Octopus and What It Means to be Intelligent
Jennifer A. Mather wrote in Natural History magazine,Evidence for the octopus's intelligence begins with its anatomy. Intelligent animals typically have large brains, and octopuses' brains are large for their body size compared to those of other animals — larger than fishes' brains and, proportionally, as large as those of some birds and perhaps some mammals. Moreover, three-fifths of an octopus's neurons aren't even in its brain. Instead, they are divided among its eight arms to coordinate the arms' remarkable flexibility. The big brain itself is mostly dedicated to learning, planning, and coordinating actions with stimuli. [Source: Jennifer A. Mather, Natural History, February 2007]
Broadly defined, intelligence is the measure of an animal's ability to acquire information from its environment and to change its behavior in response — in short, to learn. The octopus's behavioral repertoire has few fixed, preprogrammed responses, and it can respond to a given stimulus in a great variety of ways; those are both hallmarks of intelligence and learning. The sea slug, by contrast, has only a limited palette of reflexive responses, no matter what the stimulus. In one particularly vivid demonstration, published in 1970, the biologist William R.A. Muntz showed that octopuses could learn to tell complex visual figures apart by forming a new rule for each for each new set of figures. He concluded that octopuses aren't merely able to learn; they can also learn what to learn.
Ed Yong wrote in The Atlantic:. “But why did they become intelligent in the first place? Why did this one group of mollusks, among an otherwise slow and dim-witted dynasty of snails, slugs, clams, oysters, and mussels, evolve into creatures that are famed for their big brains? These are hard questions to answer. Members of the animal kingdom’s intelligentsia tend to be sociable; indeed, the need to remember and manage a complex network of relationships might have helped drive the evolution of their brains. Smart animals also tend to be long-lived, since a large brain both takes a long time to grow and helps an animal avoid danger. Apes, elephants, whales and dolphins, crows and other corvids, parrots: They all share these traits. Cephalopods do not. With rare exceptions, most of them are solitary animals that aren’t above cannibalizing one another when they meet. Even those that swim in groups, like some squid, don’t form the kinds of deep social bonds that chimps or dolphins do. Cephalopods also tend to live fast and die young. Most have life spans shorter than two years, and many die after their first bout of sex and reproduction. [Source: Ed Yong, The Atlantic, July 2, 2019] .
How Did Octopus Intelligence Evolve?
Ed Yong wrote in The Atlantic:“The combination of short lives, solitude, and smarts is unique to cephalopods. And according to a paper published in 2019 by Piero Amodio from the University of Cambridge and five of his colleagues, the traits are all linked to a particular development in the octopus’s evolutionary history: Its ancestors lost their shells.
“About 275 million years ago, cephalopods lost their shells to become more agile. But losing their shells also made the cephalopods exquisitely vulnerable. One scientist described their soft, unprotected bodies as the equivalent of “rump steak, swimming around.” The rest of the ocean seemingly agrees: Almost every major group of predators eats cephalopods, including dolphins, seals, fish, seabirds, and even other cephalopods. This gantlet of threats might have fueled the evolution of the cephalopods’ amazing color-changing skin, their short life spans, and their large brains. After all, intelligence can help an otherwise defenseless creature create new defenses. [Source: Ed Yong, The Atlantic, July 2, 2019] .
“But Ernesto Mollo from the National Research Council of Italy isn’t convinced. In a rebuttal paper, he and two colleagues argue that the evolution of intelligence takes many generations, and cephalopods would surely have been exterminated by their legion of predators if they only started that process after they had lost their protective shells. “A gradual and relatively slow evolution of intelligence would not have allowed the survival of hypothetical shell-less, but still unintelligent ancestors,” they say.
“More likely, they argue, the path to intelligence began while the shells still existed, perhaps to help early cephalopods control their jet propulsion, or process the information from their well-developed eyes and many arms. “This suggests that the gradual evolution of intelligence in cephalopods facilitated the loss of the shell, and not the opposite,” Mollo and his colleagues write.
“Amodio actually agrees with that. “We made clear that this process was really long and started before the shell was lost,” he says. Shelled cephalopods like nautiluses may not be thinking on an octopus’s level, but they can still outsmart snails or clams. They were preadapted for intelligence. But they only made that big leap forward, Amodio argues, after they got rid of their shells.
It’s not like they were totally defenseless in the interim: They could jet away quickly and squirt clouds of ink. Also, Amodio adds, think about their camouflaging skin. It’s an exceptional defense, and it must have evolved after the loss of the shell because color-changing skin would have been useless when hidden by armor. If they had time to gradually evolve one complicated defense after losing another, then surely they had enough time to evolve intelligence too?
“All of these were gradual processes that probably overlapped in time. “You can’t lose your defense before you have the alternatives ready, no question,” says Jennifer Mather, a cephalopod expert from the University of Lethbridge. “Likely, they had a good dose of the intelligence they are noted for, the shell gradually shrank or became more internal, and with less protection, the behavioral flexibility became much more important and gradually turned into the intelligence we see today.”
“Amodio adds that his ideas still need to be tested. For example, researchers could compare different species of octopuses on the same tests, to see whether species that forage in more complex ways, or live in habitats with more predators, are also smarter. That’s surprisingly hard: It’s not obvious how you would test the cognition of a creature as alien as an octopus, and it’s telling that many demonstrations of their intelligence are anecdotal. “We have a lot of evidence that their behavior is flexible, but we still need to test how smart they are,” Amodio says.
Do Octopus Have Consciousness
Jennifer A. Mather wrote in Natural History magazine, Octopuses have personalities. They learn. They solve problems. They play. Does all that add up to a simple form of consciousness? The suggestion is even more contentious than the ideas that octopuses play or have personalities. Just defining consciousness is tricky; one general definition is that an animal with primary consciousness — a dog, for instance — is aware of the complexity of a given circumstance as well as its role there and its decision-making options. Higher-order consciousness has more stringent criteria: using language, being able to report on the content of one's thoughts, being able to think about thinking. Only people and perhaps chimpanzees exhibit that exalted form of consciousness. [Source: Jennifer A. Mather, Natural History, February 2007]
But how could one tell whether octopuses have some form of primary consciousness? Some theorists say it is enough to show complex and flexible behavior, such as the octopus's clam-opening tactics. Others say an animal must be able to shift its attention from one set of stimuli to another, making decisions in rapidly changing conditions. Octopuses meet that criterion in their varied responses to a predator: they can flash unpredictable changes in pattern and color, jet off in an unexpected direction to escape, or squirt out ink to form a smoke screen.
Still other theorists argue that conscious animals build a complex, multidimensional set of internal impressions about the world on the basis of their sensory perceptions. For example, the human mind constructs a three-dimensional image of objects from the two-dimensional array of stimuli that arrive at the retina. Additional study of how octopuses analyze visual shapes might show whether they meet that criterion, too. Or perhaps a conscious animal must have a concept of self. What do octopuses see when they look in a mirror? Answering that question will be our next research project. It will be hard to say for sure whether octopuses possess consciousness in some simple form. But from what biologists already know about them, there's no denying they are some smart suckers.
Image Sources: Wikimedia Commons, NOAA
Text Sources: Animal Diversity Web (ADW) animaldiversity.org; National Oceanic and Atmospheric Administration (NOAA) noaa.gov; Wikipedia, National Geographic, Live Science, BBC, Smithsonian, New York Times, Washington Post, Los Angeles Times, The New Yorker, Reuters, Associated Press, Lonely Planet Guides and various books and other publications.
Last Updated April 2023