Transcription
Every animal follows the fundamental rules of biology. You have one brain to make the decisions, blood to carry the oxygen, and a DNA that tells your body how to do it. That was until whatever this thing is showed up.
This is an octopus. And by all accounts, this animal shouldn't be able to exist. Their lifespan is shorter than a hamster's. But yet, they're considered the second smartest animal on the entire planet. Only behind us, their brain doesn't control their arms. Their body is never its actual color. This animal should by all means be as intelligent as a blob of jell-o. Yet, studies have shown they're smarter than squids, smarter than giant squids, smarter than polar bears, smarter than any pet dog or cat you've ever had.
How does a creature that lives for only a year become this capable? What kind of evolutionary path creates a genius and then completely kills it off before it can develop any smarter? And what actually made these seemingly weak creatures need to become so adaptable?
To understand the octopus, you have to stop thinking of it as an animal. At least not one single animal. In a human, the brain sits at the top, sends signals down the spinal cord, and tells the hands and feet exactly what to do. If you want to pick up a glass of water, your brain calculates the distance, controls the grip, and monitors the movement. The hand is just a tool.
An octopus's brain is their hands. An octopus has about 500 million neurons, but only about 10% of those neurons are in the central brain. Another 30% are located in the optic lobes. And everything else, it's all in the arms. Each of the eight arms has its own mini brain. They have their own clusters of neurons that can process information, sense their environment, and make decisions without ever checking it with the head. It's like having eight separate living beings attached to your body, forcing you to do whatever they feel like.
The central brain might give a general command like move towards that rock, but it doesn't micromanage how the arms get there. The arms figure out the terrain, decide which suckers to use, and handle the mechanics of the movement all on their own. They think, they taste, they react.
Researchers proved this with the autonomous arm experiment. They found that if an octopus arm is severed, it doesn't just go limp. For a short period of time, the arm remains alive. It will still react to stimuli. It will try to catch food. It will even try to pass that food back towards the place where the mouth used to be. This isn't really like how a reflex works. There is real intelligence going on. The arm is looking for food because that's what the arm does. This is what allows the octopus to do a bunch of things at the same time. Not because it has a fast brain, but because it's running eight of them together, or well, nine, including the real one.
But if the arms are all independent from each other, it has one major problem. You don't know which other arm belongs to you. So, how do you stop your arms from eating each other? In a decentralized system where the central brain doesn't always know what the arms are doing, there's a very real risk that an octopus could accidentally grab itself, get tangled, or even start eating its own limbs, thinking they were prey. And yet, you never see this happen.
For a long time, we didn't know how they avoided this. We assumed the central brain was just very good at tracking the position of every limb. But then, researchers noticed something strange. Octopuses genuinely don't know where their arms are unless they are looking at them. They lack proprioception, which is that sense of self movement and body position the humans use to know where our hands are, even in total darkness. This seems wildly inefficient for an animal that has four times as many arms as us.
If the brain doesn't know where the arms are, then there has to be a mechanical or chemical reason why they don't stick to themselves. It turns out the solution is built directly into their skin. Octopus skin produces a specific chemical that acts as a shutdown signal for their suckers. When an octopus arm brushes against another part of its own body, the suckers sense that chemical and instinctively refuse to grip.
Researchers tested this by offering octopuses severed octopus arms. Yeah, this is a bit of a sick experiment, but anyways, normally an octopus will grab anything that smells like food, but when they touch the severed arm, the suckers wouldn't grab it. The chemical handshake was still active in the skin, telling the suckers, "This is you. Don't eat this." The only way researchers could get the suckers to grab was by removing the skin from the severed arm. Without the chemical signal, the suckers treat the limb like any other piece of meat.
This shows that the intelligence of an octopus isn't just thinking in the way we understand it. It has parts of its body that can deal with things by themselves without needing a main brain to control every detail.
But every intelligent animal, from humans to orcas, is known for being social. It's basically what makes an animal intelligent. So why do octopuses always seem to be so lonely? For as long as we've been studying them, the official word on octopuses was that they were solitary animals. The standard belief was that they lived in solitary dens, hated their neighbors, and only came together to fight or mate. If two octopuses met in the wild, the assumption was that one of them was going to get eaten.
But that started to change with the discovery of a site off the coast of Australia that scientists called Octopolis. It was a small patch of seafloor where instead of being spread out, dozens of Sydney octopuses were living right on top of each other. Octopolis was created because at some point a metal cylinder was thrown into the water in an area where the sand is too thin for any animal to create a proper burrow. Other animals looked at the object and completely ignored it. But the octopuses saw an opportunity to create residences for themselves. The octopuses were building their own homes. They were interacting. They were living in a high-density city.
A second site called Octalantis was found nearby a few years later. But unlike Octopolis, Octalantis was created completely independent of human activity. The octopuses there learned how to pile up shells to form a much more stable structure than loose sand, allowing tunnels to be dug without collapsing. These weren't just random clusters of octopuses. These octopuses were simply interacting, something we thought they were incapable of. They had a language of signals. They would change their color and posture to show dominance or submission. They also had a very human way of dealing with neighbors they don't like. They would throw things. Octopuses at these sites were observed using their siphons to blast jets of water at silt, shells, and algae, aiming them directly at other octopuses. Sometimes it was a territorial dispute, and sometimes it just seemed like they were annoyed.
The discovery of Octopolis and Octalantis proved that octopuses aren't naturally solitary. They are opportunistic. When the environment provides enough food and shelter, they are perfectly capable of forming a society. They can learn to navigate social hierarchies and communicate with their own kind.
But if the octopus can create its own civilization, why hasn't it dominated everything yet? Well, the answer is actually very simple. They all die. In basically all of nature, there's usually a pretty large correlation between intelligence and lifespan. Humans, whales, elephants, and parrots are all highly intelligent, and they all live for decades. It makes sense. It takes a long time to grow a complex brain, and it takes even longer to fill that brain with useful information and experience. If you're going to spend the energy to become a genius, you need to live long enough to make that intelligence pay off.
The octopus is the only major exception to this rule. Most octopus species live for around 2 years. The giant Pacific octopus, the largest and arguably smartest of them all, usually dies by the age of four. This means they grow disgustingly fast, sometimes increasing their body weight by 5% every single day. But of course, this doesn't last long. This creates a weird lifespan paradox. An octopus can learn to unscrew jars, solve mazes, and recognize individual human faces. They show curiosity and playfulness, but they die so quickly that they can never pass that knowledge down. Every octopus starts from zero. There is no culture in the octopus world. There are no parents to teach the young how to hunt or where to hide. Imagine if every human died at the age of five. Even if we were all born geniuses, we would never build a civilization because we'd never have enough time to record our findings or teach the next generation. The octopus is trapped in a loop of animal brilliance and then just death. They reach the peak of their intelligence right as they're about to die.
But what's causing this isn't just dying of old age. It's actually an intentional design caused by the octopus itself. Their death is triggered by something called the optic gland. This is the octopus version of the pituitary gland and it regulates their hormones and reproductive cycles. For most of their lives, it functions normally. But once an octopus mates, the optic gland undergoes a massive shift. It stops being a regulatory organ and starts being a death gland. The moment a female octopus lays her eggs, everything in her body starts to change. She stops eating. She loses interest in her own survival. She spends all her time guarding her eggs, blowing water over them to keep them oxygenated, and defending them from predators. This process is called semelparity. It's a downward spiral. Her tissues begin to waste away. Her skin loses the ability to heal. She becomes lethargic and eventually dies right as the eggs begin to hatch.
For a long time, we thought this was just a noble sacrifice. A mother giving her life for her children. But it turns out it's not that dramatic. Researchers performed a famous experiment where they surgically removed the optic gland from mother octopuses after they laid their eggs. And the results were immediate. The octopuses didn't die. They stopped guarding the eggs. They started eating again. They went back to their normal lives. In some cases, they lived for months or even a year longer than they should have.
But why would nature create such an advanced animal just to install a self-destruct button in it? If an animal is this incredibly smart, evolution usually wants these things to stay alive. It turns out there's actually a massive threat to the octopus that forces them to have short lifespans. Another octopus. See, the octopus grows at an absurd rate. And to grow so fast, you have to eat constantly. If these animals lived for 20 years, they would quickly run out of crabs and fish to eat in their territory. So, what is the next best source of protein in the ocean? Each other. Octopuses are heavily cannibalistic. If the older massive generation of octopuses were allowed to stick around after the babies hatched, they wouldn't protect their young. They would simply eat them. The optic gland essentially prevents this. By forcing the parents to starve themselves right as the eggs hatch, evolution guarantees that the millions of newly born octopuses actually have a chance to enter the ocean without being instantly devoured by their own parents.
If you remember, octopus arms actually won't eat each other, but that's specific to a chemical signature of the same octopus. Also, wiping out your entire population each year lets you accelerate your own evolution. Animals that live for decades, like sharks or whales, take hundreds of thousands of years to adapt to environmental changes. But because octopuses reproduce and die so quickly, their species gets a brand new chance to mutate and adapt to their surroundings every single year. If the water suddenly gets colder or a completely new predator moves into the reef, the octopus population can adjust to it in just a few short generations. And an octopus is also really easy to target because they are squishy. All large marine animals eat octopus, so keeping alive an animal that would die anyway doesn't make too much sense, which is why nature decided it wasn't really worth keeping them around too long.
Maybe these creatures aren't reaching their max potential, which could be sad, but it could also be a really good thing, too. I don't need genius octopuses running around taking over the world. It is a little strange, though, that these creatures don't just die almost instantly in the ocean. I mean, being that squishy doesn't necessarily make you very defensible to any even midsized fish, let alone a whole shark.
We all know the octopuses can change color. That's what they're famous for. But hiding from apex predators requires more than just changing colors. Instead of just looking like a rock, they essentially become rock. They use something called papillae, which are basically little muscle groups in the skin that can tighten or relax to change the body's texture. An octopus can go from completely smooth to rough in seconds. So, when the octopus changes its appearance to match a rock or a coral reef, it's actually copying every detail of the shape, too, not just the color. It's what lets the octopus stay out in the open and still survive.
And they do all this while being, as far as we can tell, completely colorblind. Octopuses only have one type of photoreceptor in their eyes, which usually means they can only see in black and white, and yet they match the colors of their environment perfectly. This is known as the colorblind paradox. We still don't fully understand how they do it. Maybe it's related to the unusual shape of their pupils, which might help them detect color in indirect ways, or because their skin itself can see light with the fake brains in its arms.
The octopus does remind us that intelligence might come in a few more ways than just which animal is closest to human. Whether they're truly more intelligent than some other animals like dolphins or sperm whales is debated, but one thing is for sure, this guy is weird. Thank you for watching and check out our video on the colossal squid here. It's a lot bigger than an octopus.