We live on a planet full of fascinating living beings. Beyond humans, who have been able to build entire civilizations with unparalleled technological and social frameworks, other species also show incredible skills and characteristics.

There are birds capable of flying at tens of kilometers per hour, mammals whose size exceeds that of a small building, and cats that can detect prey in the most absolute darkness. Skills worthy of the superhero in any comic book.

But among the extensive biodiversity that still inhabits the earth, unfortunately less and less, lives an animal whose properties are particularly noteworthy: the octopus, of which some 300 different varieties have been identified (cephalopods).

In this article we will stop to analyze what makes it so fascinating, with a special emphasis on the anatomy and the properties of the octopus’ brain , an organ that gives it a unique cognition.

What does the octopus’ brain look like?

The first thing that strikes you when you look at the octopus’ brain is that is by far the largest of all invertebrate brains . Thus, it dominates at the top of the pyramid an entire category whose representatives are counted in tens of thousands (about 55,000). Furthermore, it has the highest ratio in the equation of the relative weight of its brain with respect to the body, within this same classification, a common indicator for inferring the intelligence of any living being. This is a representation of it, which appears in The Anatomy of the Nervous System of Octopus Vulgaris , by J. Z. Young:

The ratio of the octopus’ body size to its brain is similar to that seen in mammals such as whales, which have been able to demonstrate great intellectual gifts and sophisticated social skills. In addition, the number of neurons (in the raw) is close to that of a dog, an animal that has accompanied man since the dawn of time and that stands as one of his most faithful companions. This fact is an evolutionary exception that has attracted the interest of the entire scientific community.

Your nuclear brain, inserted in a cartilage capsule inside your head (it has no bones), represents only a discrete percentage of the total length of the nervous system. The rest of the neurons that form it are located in its tentacles , arranged as interconnected ganglia (mini-brains), and giving shape to a very complex constellation of cells (100,000,000-500,000,000) that react tremendously quickly to environmental triggers, which makes it a unique system in zoology.

If we analyze the distribution of their nervous system, we observe that only 10% of it is located in the predictable area for mammals: the interior of the head. Thirty percent is located in two large lobes (15% for each case) that border its lateral surface (behind both eyes) and whose function is to process visual stimuli. Finally, the remaining 60% is distributed among all the tentacles, so that the highest percentage of neurons that this animal has is present in almost all of its body mass .

In the brain of the octopus, aligned contiguously, are organs that allow the animal to orient its position in space in places that light cannot reach (as some live in the abyssal depths), which is complemented by a pair of eyes extraordinarily adapted to darkness (and similar in structure to those of humans). We are talking about statocysts; which they share with species such as bivalves, echinoderms and crustaceans.

In general terms, the octopus has a multiple brain , and not only a nerve structure located inside its head. This organ is distributed throughout the body, forming ganglia that control each of its extremities, and that provide it with an enormous adaptive capacity.

This is a different structure than that of mammals, an evolutionary “alternative” that could provide us with information about forms of consciousness that are still beyond our comprehension (and which have recently been used to design robotic artificial intelligences).

The intelligence of the octopus

If we go back to the evolutionary history of octopuses, we find that they represent an example of extraordinary intelligence not only in the category to which they belong, but in the animal kingdom as a whole. They are living beings older than the dinosaurs themselves , who have had the opportunity to survive for millions of years to forge refined cognitive skills, and who constitute one of the greatest examples of past intellect that we can access.

Studies on this issue have shown that are able to use tools (such as coconut shells in which to shelter) and learn through observation of other octopuses solving some problem, keeping what they have assimilated for days without the need to rehearse it. In addition, the octopus (in its more than 300 species) has a unique capacity: each of its tentacles can “think” for itself.

More specifically, when an octopus observes a situation in which it has to act (a prey to feed on or a predator to flee from), it sets in motion a reaction involving every part of its body, in order to determine the most efficient pattern of behaviour. In this way, and due to the positional multiplicity it has (as it lacks joints), it is able to select an enormous variety of actions to solve problems (from opening jars to getting out of complex labyrinths).

The process that is set in motion is different from that of human beings. In our case, the demands of the situation are compared with a restricted body scheme (rigid and poorly articulated skeleton), which results in limited reactions to resolve situations. The octopus is so flexible that it does not need to consider its body limits, so it only stores behavioural patterns that are activated when needed , thus offering a faster and more effective response to deal with environmental demands.

In addition to all this, the brain distributed in the tentacles can establish communication with the rest of the octopus’ extremities, so that they coordinate without becoming entangled (which would be a vital risk). This is because each of the ganglia not only connects to the centralized brain, but also to the others, thus enabling extraordinary fine motor skills. Everything is enhanced by the fact that the brain located in the head barely participates in the moment when the suction cups of the rest of its appendages act, which have their own free will.

It has been observed that the sectioning of one of the tentacles (they can mutilate themselves when trying to escape) does not imply that it will “die” immediately, but that it will continue to move and act with purpose for about an hour, confirming that it has autonomy. For this reason, despite being separated from the body, they can take decisions such as camouflaging themselves (safeguarding themselves from danger) and recognize another tentacle as a part of themselves (through a kind of chemical receptors located in the suckers).

The personality of the octopus

In addition to possessing great intelligence, there is evidence that cephalopods have stable personality traits that differentiate them in a very noticeable way, and that even have a tendency to group according to the degree of similarity (demonstrating social type preferences). Some of them are hurricans and spend most of their time locked up in caves, which they plug up with rocks to increase their privacy (their elasticity allows them to “sneak” into almost any hole).

There are also very aggressive octopuses, to the point of being able to attack and devour other octopuses. On the other hand, can form an idea of the human beings they are comfortable or uncomfortable with , that they like or dislike; forging a memory that lasts months or even years (showing a large store of long-term memory). Being animals that do not have a long life expectancy, they can be said to create memories that extend throughout their life cycle.

Finally, it has been shown that octopuses are prone to play with other members of their species, a behaviour that has been classified as an indicator of high intelligence in the field of ethology. This is because it is an action that does not seek to guarantee survival nor is it explained as a reaction to immediate environmental contingencies, but rather has as its aim enjoyment and leisure without any great pretension. This recreational habit is observed exclusively in the most complex species, especially among vertebrates.

Other great things about octopuses

Up to this point, it’s become clear that octopuses are fascinating animals. Beyond their history (which goes back 33,000,000 years), their amazing intelligence and their ability to have a personality of their own ; they also have a number of other characteristics that make them one of the best adapted and prepared animals for survival (after all, they have been doing it for a long, long time).

For example, they are capable of camouflaging themselves perfectly in their environment, of propelling ink to avoid a predator that may have detected them, of attacking their prey with a powerful beak and of poisoning any overconfident fish with paralyzing toxins. You could say it’s one of the great kings of the ocean… in fact they even have blue blood! And pumped by a total of three hearts, no less.

In conclusion, octopuses remind us that we live in a wonderful world, and that nature is capable of shaping authentic works of engineering whose presence will always fascinate the curious human being. It is our responsibility to look after the health of our planet , so that they can continue to stimulate the imagination of future generations.

Bibliographic references:

  • Guglielmino, E. and Tsagarakis, N. (2010). An octopus anatomy-inspired robotic arm. International Conference on Intelligent Robots and Systems, 18(22), 3091 – 3096.
  • O’Brien, C.E., Ponte, G. and Fiorito, G. (2018). Octopus. Animal Behavior, 4(2), 1 – 8.