Armed with eight tentacles, color-changing capabilities, and more intelligence than you ever gave them credit for, octopi display behaviours much more complex than your typical mollusk. Their use of tools and creative resourcefulness has been key to keeping them from being eaten on the ocean floor – at least until humans came along.
Cet article existe également en français : Cthulhu expliqué par la science : pourquoi les pieuvres sont à la fois terrifiantes et géniales (Translation/traduction : Pierre-Sofiane Kadri)
We’ll start this off on a personal note, with a confession: I, David Davila, am afraid of octopi.
We associate octopi with a myriad of unique and interesting traits: eight legs, ink, suckers, and delicious in paella. But, in fact, octopi have even more offbeat traits, paired with unexpected intelligence that should start to strike fear into the hearts of land-dwellers.
To start with, octopi have beaks, similar to a parrot’s. It’s the only hard part of their bodies. However, because it’s the only hard part, octopi can fit through amazingly small spaces to get where they need to go – organs shift and reshape as an adult male octopus squeezes through a small tube and exits just fine on the other side. In addition, most octopi are known to have color-changing abilities: they can instantly camouflage to their surroundings. As if this weren’t enough, certain octopi produce toxins as a defense. The blue-ringed octopus, grapefruit sized and covered with electric-blue rings, bites with venom known as tetrototoxin – a neurotoxin for which we currently have no antidote.
Surely, all these features are intimidating, but is it really enough to be scared of all octopi? The true extent of an octopus’ abilities only comes into play when all these biological tools are paired with its most valuable asset: its intelligence.
A distinction should be made between innate animal behaviours - such as a spider’s ability to build an intricate and efficient web - and behaviours that must be learned, such as the octopus’ tendency to seek out lobster traps and steal the tasty prize waiting inside. One shows abilities derived from millenia of evolution, and one shows legitimate intelligence: the ability to take in information from your surroundings and recognize patterns. It is to this kind of adaptable intelligence that we attribute the octopus’ complex behaviours, such as building fortresses and shelters from coconut halves and shells, or carrying around a tool for later use.
Possibly the most intricate behaviour and display of the octopus’ intelligence (learned or inherited) can be seen in the abilities of the mimic octopus. Having been observed to mimic no less than 13 different species, this octopus is able to use its color changing abilities and flexible body to hide in plain sight, disguised as highly venomous or uninteresting marine creatures. Additionally, their large repertoire of mimicry allows these octopi to choose different sea creatures to mimic, based on the specific predator. In the presence of a damselfish, for example, the mimic octopus will bury its head and six legs, and wave two yellow-and-black banded arms to resemble the dangerous sea snake - a highly venomous animal and known predator of the damselfish. Almost like a Dementor from the Harry Potter series, the mimic octopus is able to change its appearance at will and become the thing its predators fear most.
So where does an octopus get its smarts? Unsurprisingly, octopi have intricate nervous systems that are as unique as they are complex. Two-thirds of an octopus' neurons are found in its tentacles, creating a complex network that practically gives each arm a mind of its own. A tentacle whose connection to the brain has been severed can no longer be used by the octopus, but if touched, it will reflexively reach out, whip-like, in the same way it normally would. Shockingly, less than a tenth of their neurons are in their “central brain”, but it is here that the circuitry for learning and memory is found. Thanks to their vertical lobe, analogous to our own memory center called the hippocampus, they are able to learn mazes and solve “problem boxes” to reach food inside. Particularly impressive for invertebrates, they display “observational learning”: after watching other octopi learn a task, they learn the same task much faster. While such learning is found in complex, social creatures, octopi are largely solitary creatures and thus this kind of learning most likely arises from the sheer complexity of their neural systems.
I may have been misleading in my opening sentence: yes, I am afraid of octopi, but it is a reverent fear, founded in awe and respect for such an amazing creature. As humans, we realize the respect we ought to be giving more intelligent creatures, such as dolphins and apes, by protecting them through laws and environmental policies. However, octopi, which have been killed and eaten for centuries, enjoy no such protection, despite being classified as “honorary vertebrates” by the United Kingdom when it comes to using them in research. Indeed, nearly every animal widely eaten by humans eventually shows a drastic decrease in population size due to overhunting, often until they become endangered. In order to ensure the prolonged survival of these mystical creatures of the sea, we might want to think twice before ordering that octopus sushi.
About the author:
David Davila (@cozyneuroses) is a Master 2 student studying neuroscience in the program Approches Interdisciplinaires du Vivant. He recently won runner-up and audience choice prizes in the international science communication competition ,Famelab, and is co-host of a new neuroscience podcast called “Brain Drain”.