Of all creatures on Earth, octopuses seem closest to alien beings. It’s not that they look weird, it’s that they ARE weird, and incredibly clever, too. Recent paradigm-shattering discoveries about octopuses (yes, octopuses really is the correct plural- the word is of Greek origin, not Latin) just keep adding to their other-worldly mystique.
So, let’s take a look at eight mind-blowing octopus facts.
1. Octopuses have been around for 300 million years and are among the oldest living creatures on Earth.
To put this in perspective, dinosaurs evolved on the scene about 250 million years ago, making octopuses a solid 50 million years older. It was only 1.5 million years ago that the first ancestors ressembling homo sapiens evolved into existence, which is practically yesterday to an octopus. More incredible still, 99% of all the species that have ever lived on Earth are now extinct, leaving octopuses among that scant 1% to have survived. That’s pretty darn old and pretty darn adaptive.
Octopuses aren’t just way old and staggeringly successful. The latest research suggests they really haven’t evolved all that much in 300 million years! Which brings us to mind-blowing fact #2.
2. Octopuses adapt in real time to their environments by editing their RNA, rather than evolving slowly over millions of years by random DNA mutations.
If DNA is the master codebook with all the instructions for how to build every protein in an organism, RNA is the transcriber and translator of the code into actual proteins. In every life form, RNA is a reliable translator, never altering so much as a nucleotide of code, except in rare accidents. Even if RNA makes an occasional mistake, it isn’t passed on to the offspring because the original DNA remains unaffected.
Octopuses, however, have blown the whole RNA operation out of the water. A joint study by the University of Chicago and Tel Aviv University published in “Cell” in April finds that octopuses (and their close cousins squid and cuttlefish) edit the RNA of nearly half of all the genes they transcribe. It’s as if their DNA code is a mere suggestion for how to build proteins- a jumping off point for the creative embellishment of RNA. The study finds octopuses and their cousins have tens of thousands of genes in which editing routinely occurs. By comparison, only a few dozen of a human’s 20,000 genes have the option for RNA editing.
(You may have deduced from the above statement that octopuses have more genes than humans. They do. Octopuses have 33,000 genes- half again as many as humans. Do cold-blooded animals have more genes than warm-blooded animals? If so, why? A great question for a coming article!)
All this RNA editing means octopuses and their cousins are adapting to their environments in real time, not waiting around for random mutations in their DNA to save the day or ultimately sink them. This degree of RNA editing has not been found anywhere else in the animal kingdom. Nowhere.
The trade off, the authors of the study say, is the evolution of the octopus is slowed significantly because the adaptive changes in the RNA are not passed on to their offspring. And yet, this non-evolutionary strategy is profoundly successful.
One of the study’s most fascinating discoveries is the vast majority of RNA editing occurs for genes of the octopus nervous system. Which brings us to mind-blowing fact #3.
3. Octopus brains spread from their throats out through their arms.
Take a moment to wrap your head around that one.
The octopus has a small, doughnut-shaped central brain surrounding its throat, and two optical lobes, one for each eye. Fully 65% of its remaining neurons are operating in its eight arms. A human brain contains about 85% of the neurons in a human body. So, you can see that the arms of an octopus come awfully close to being in charge of the whole show.
This much brain power is invested in its arms for a number of amazing reasons. One is the extraordinary flexibility, range of motion, and ability to lengthen each arm without any bones to act as levers. This means the tension of each muscle fiber has to be perfectly orchestrated with all the rest to be rigid, flexing or relaxing at any given moment in order to curl, slither and stretch the way they do. The number of motor neurons required to coordinate so many muscle fibers so precisely without the help of bone levers is astounding. But that’s just the tip of the tentacle, so to speak.
Each octopus arm has over 200 suctions cups and these suckers are no passive appendages. Each suction cup can independently suck, dilate, shrink, extend, pinch, and coordinate with nearby suction cups to pass objects from one to the other. You could almost think of them as 200 tiny hands attached to each arm. Multiplied by eight arms and you have more than 1,600 independent, hand-like suction cups per octopus. That requires whole lot of neuronal activity.
But wait! There’s more! Each arm can operate fully without any input from the main brain. Each arm can interact with its surroundings, make decisions, and act of their own volition without a single neuronal impulse from its central brain. When one arm needs assistance from another, the arms communicate directly with one another, bypassing the central brain completely.
4. Those octopus brains are quite clever.
You may have heard octopuses can unscrew jars to get to tasty morsels inside, but did you know they can open child-proof caps, too? Some of us humans still struggle with that! They’ve also been known to routinely escape their aquariums when researchers aren’t looking, make a meal of the fish in the next tank, and get back before the staff realizes what’s happened.
The veined octopus of Indonesia has been observed scavenging for coconut shells, carrying them to secluded locations and using them as shelters. Could this be evidence of tool use? The question is still open.
The anecdotal evidence is quite entertaining. But studies are beginning to confirm the astonishing intelligence of octopuses, especially for spacial learning. There’s even evidence from one study showing octopuses most definitely recognize which humans bring them food and which ones are nasty to them!
The research is dribbling in slowly because designing experiments for these creatures is a challenging task.
So, if their clever brains aren’t in the bulbous sac that floats above the arms, what the heck is that thing?
5. The mantle, the large sac-like structure, isn’t the octopus head, but its belly.
Now that you know the octopus’s brain is more in their arms than anywhere else, you probably already figured this one out. But you couldn’t be faulted for thinking that big bag, the mantle, was a head. Instead, the mantle contains the octopus’s internal organs: digestive tract, reproductive organs, kidneys, gills and its three hearts. Yup, that’s another octopus oddity- they have three hearts.
The octopus has one heart for each gill, and one systemic heart. The heart for each gill would be akin to a mammal with one heart for each lung pumping oxygenated blood to the systemic heart. The systemic heart pumps blood to the rest of the octopus’s organs, arms and to its skin.
The skin of the octopus is particularly important, as you’ll see in the next mind-blowing fact.
6. The octopus is color-blind and cannot see infrared, but its skin can match the color and texture of its surrounds nearly perfectly, including in the infrared range.
How is this even possible? It turns out octopus skin is covered in opsin, a light-sensitive protein found in the retina of the eye. It’s as if their skin is a covered with light-sensing eyes. Minute changes in light are registered in the opsin and those changes are communicated to nearby pigment-containing cells called chromatophores.
Chromatophores are little cellular sacs of blue, red, yellow and black pigments- roughly the same as the inks in your color printer- plus two bonus colors. They have an added sac of white pigment and the red pigment includes infrared. Because many sea creatures see in the infrared range, an octopus’s cover could be blown without it! Tiny muscles dilate and contract the openings of the pigment sacs, adjusting the degree of their dilation to match the coloration of their surroundings depending on what the opsin in its skin is “seeing.”
But mere coloration isn’t enough to create a convincing camouflage. To mimic the quality of reflected light, octopuses have chromatophores that act as tiny, shimmering mirrors called iridophores. These cells also dilate and contract to correspond to the amount of light reflecting from the surface of the objects around them, creating a perfect illusion of blending in.
The final bit of camouflage brilliance is the ability of the octopus to control the contours of its skin minutely. The closest thing we have to this skill is goosebumps, but we would have to bring them on at will and simultaneously choose where they arose and how high. While we have no such ability, octopuses have it down to a science.
Put together the skin layered with opsin, like a giant sheath of eyes, tiny pigment pouches, minuscule mirror-like cells, and skin that can morph into any texture and you have one heck of an amazing camouflage apparatus. Now imagine an octopus doing all this in the blink of an eye!
This clip from David Gallo’s 2007 TedTalk “Underwater Astonishments” illustrates this amazing feat.
Mind-blowing, is it not?
Now you may be asking yourself, why didn’t the octopus just keep swimming away to escape the photographer? Why did it stop? I’m glad you asked, because that brings us to fact #7.
7. The octopus’s systemic heart stops beating when it swims, so it can’t swim very far.
Remember, of the octopus’s three hearts, the systemic heart pumps blood to its organs and its arms. So when an octopus swims, it can’t go very far without oxygenated blood circulating to its cells and removing carbon-dioxide. It can only swim a short distance before it has to stop. This could be why the octopus has such incredible powers of camouflage- it really can’t move very far so it has to hide very well.
Interestingly, the octopus’s close cousin, the squid, has no heart-stoppage issue, and uses water-propulsion to give it jet-like speed when it swims, and it can swim as far as it likes. Yet, the squid, too, has extraordinary powers of camouflage. Fascinating, isn’t it?
If octopuses are terrible swimmers, you may be wondering how do they move from one place to another?
Octopuses prefer to walk, thank you. They’re not exactly built for speed, but octopuses use their arms to shuffle along the ocean floor. If they’re carrying an object, say a coconut for later use as shelter, an octopus actually stands up, sort of, and uses its back two or three arms to walk along.
And where might an octopus be going?
8. Octopuses really do have gardens.
Well, they’re more like rock gardens. Octopuses often collect bits of coral, small rocks and found objects. They bring their treasures back to their dwellings and arrange them in their front yard. It’s not understood why octopuses engage in this behavior but it seems rather obvious. These other-worldly creatures, often thought to be the most alien of all animals on Earth, know there’s no place like home.