Why are octopuses endowed with one of the most remarkable intelligences in the animal kingdom?

While the Oscar for best documentary film has just been awarded to “The wisdom of the octopus”, the intelligence of these strange animals fascinates more and more. How does such a special being perceive the world? Very lucky is the one who can say it with certainty.

Octopuses, or octopuses in the language of Victor Hugo, are cephalopods, a class of marine animals that are part of the
mollusks. Equipped with eight arms covered with suction cups and a muscular body without bones or shells, are endemic to our oceans. About 200 species are distributed in all the marine waters of the globe. While our last common ancestor with them dates back to
500 million years, when we study them, they present disturbing similarities to us, through their staring eyes,
their brain functioning surprisingly close to ours or their curiosity and their desire to explore which reminds us of our own thirst for knowledge. Studying these similarities, which we call evolutionary convergences, allows us to better understand how environment and evolution similarly shape organs and behaviors.

About 200 species of octopus (or octopus) are distributed in all the marine waters of the globe © Sigmund / Unsplash

On this last point, the behavior of octopuses seems to indicate an impressive intelligence. In ethology, science studying behavior, we study this intelligence, which we rather call cognition. Cognitive abilities can be defined as the processes by which information from the environment is perceived, processed, transformed, retained and then used to make decisions and take action.

From a behavioral point of view, the flexibility with which individuals adapt and adjust their behavior to changing and new situations is a good measure of their cognitive abilities. Numerous studies on octopuses show that they exhibit great flexibility in their behavior, whether in their natural environment or in an aquarium in a laboratory.

Gifted for offense and defense

Let us first take the example of defense mechanisms in octopuses. Faced with their multiple predators, octopuses are camouflage aces, because they can mimic their environment by changing the color and texture of their skin instantly and in various ways, thanks to pigmented cells called
chromatophores and multiple muscles covering their epidermis.

In the absence of a shell, octopuses are very vulnerable, and they will seek to hide, preferably in a shelter in the form of a cavity under a rock: octopuses arrange and maintain their shelter by removing sand and adding stones and shells to better close the entrance. Others will prefer to silt to hide, or to cover themselves with shells, and some will even carry their shelter in their arms, a behavior considered as a use of tool. This is the case with coconut octopus, who was observed carrying half a coconut shell in order to hide underneath at the slightest danger.

Octopus using a coconut as a tool / AFP

Octopuses are also of formidable predators themselves, and their attack mechanisms adapt to the wide variety of prey they consume, namely all types of shellfish and crustaceans, but also fish and even other cephalopods. They can use their vision and camouflage to hunt, or their arms to explore, touch and taste the environment and grab any food within range. They can have interspecific interactions to hunt, and cooperate with certain fish, especially groupers, to find hidden prey. They learn to beware of crabs carrying stinging anemones and attack them cautiously without being stung.

When they consume shellfish and molluscs, octopuses can either force open the shell, possibly sliding a small stone to block the closure, or inject a toxin paralyzing that will allow the shell to open easily. The toxin is inoculated into a very specific muscle after drilling the shell, and the octopus must learn and remember where to drill each shell.

Creatures to watch closely in the lab

The cognitive abilities of octopuses are also extensively studied in the laboratory. For example, in our EthoS laboratory, we are currently working on the memory and planning abilities of common octopus. They are animals that are complex to study, especially because of their great strength, because they can easily destroy research devices: beware of submerged cameras, they are able to open waterproof cases to bypass them! In addition, they are devoid of bones, and can easily escape through the smallest hole; Endlessly curious, they grab hands and landing nets at the slightest maintenance of their aquarium.

Game with a common octopus from the EthoS laboratory © Lisa Poncet

Opening jars, while impressive and often used to illustrate the intelligence of octopuses, is not their most exceptional ability. This task is easy for them thanks to their dexterity and their capacity for gripping, but ultimately octopuses are very slow in carrying out this task: even overtrained, an octopus always takes more than a minute to open the pot and grab the crab. Octopuses, however, remain gifted in their way of handling objects, for example by modifying their orientation to slide them through a small opening in a wall.

They also excel at discriminative learning: when faced with two objects, they learn to attack an object in exchange for a reward, based on its characteristics, such as color, shape, texture or taste. They can retain these learnings for several months, and are also capable of generalization, a complex task that requires spontaneously extending the learned rule to new objects based on their similarities (size, color, roughness) with those previously encountered. For example, octopuses having learned to recognize and attack a real ball are able to reproduce this learning on a screen and thus attack a virtual ball.

They show conditional discrimination, that is, they can modify their choice according to the context: for example, they can learn to attack an object only in the presence of bubbles in their environment and to restrain themselves from it. attack in their absence. They are capable of spatial learning, and can find an invisible refuge by remembering its position in space. They can also use visual cues to know how to orient their arm engaged in an opaque device.

The blue-ringed octopus is one of the most poisonous marine animals in the world, its poison causes total paralysis of the body – including in humans © Kris Mikael Krister / Unsplash

Finally, octopuses are able to learn by observing their peers. This is surprising, because they are animals described as predominantly solitary (although communities of octopus have been observed occasionally). However, after observing a congener choosing a particular object, the octopus is able to reproduce this behavior without additional learning. But although impressive in their lab learnings, octopuses remain surprisingly erratic animals in their responses, especially in visual discrimination experiments, where their performance rarely exceeds 80% success when other animals do almost perfectly. .

Thus, if we take the definition ofintelligence, we observe that octopuses validate all the conditions: they show great flexibility in obtaining information (use of several senses, social learning) in processing this information (discriminative and conditional learning), in its retention (long-term memory), and in its use (adaptation of behavior to different predators and prey).

But don’t get me wrong: just because they are the center of attention doesn’t mean they are the smartest in our seas! In the cephalopod schoolyard, the octopus would rather be the turbulent pupil. The cuttlefish, she would rather be the first of the class. These cousins ​​of octopuses are surprisingly ignored by the general public, and yet at the center of much research in ethology laboratories around the world: less jack-of-all-trades than octopuses, yet they have
learning abilities without commonality, being able to learn complex rules in a very short time, and once they have been acquired, they apply them to perfection.

Finally, cephalopods show us that it is not necessary to look for intelligent life forms in the stars, because there is still so much to discover in our seas!

This analysis was written by Lisa Poncet, doctoral student in neuroethology at the University of Caen Normandie.
The original article was published on the website of The Conversation.