The Octopus That Used a Mirror to Find Its Hidden Lunch
Summary
Scientists put a mirror in a tank with three octopuses and hid a crab where they could not see it — and the octopuses figured out how to use the reflection to track it down! Come learn how octopus brains, arms, eyes and suckers work, why mirrors fool almost every animal on Earth, and what this squishy genius can teach you about thinking like a scientist.
Transcript
0:00Mirror Lunch Mystery
Imagine you are super hungry, and your lunch is hiding behind a wall. You cannot see it. You cannot reach it. You do not even know which way it went. But there is a mirror in front of you, and in that mirror, you spot something moving. A crab. Tiptoeing sideways. Would you figure out what to do next? Three octopuses in a science lab did exactly that. Scientists set up a tank with a mirror, tucked a crab where the octopus could not possibly see it directly, and then they waited. And watched. And then their jaws dropped, because those octopuses did not just stare at the shiny glass like most animals do. They used it. They looked at the reflection, worked out where the real crab must be, and went straight for lunch. That is not luck. That is a squishy, boneless, eight-armed brain solving a puzzle. And by the end of this video, you are going to understand exactly how it pulled that off. But first, you need to meet the strangest animal in the entire ocean.
0:52Meet The Octopus
Meet the octopus. If you tried to design an animal from scratch, you probably would not come up with this. It has eight arms. No bones at all, not a single one, except for a tiny hard beak. Its whole body is basically a squishy bag of muscle that can change shape like putty. And here is your first wow-fact: an octopus can squeeze its entire body through a hole no bigger than its eyeball. That means a big octopus, the size of a beach ball, can pour itself through a gap the width of a coin. Scientists have watched octopuses escape tanks by slipping through a pipe barely wider than a pencil. Octopuses live in every ocean on Earth. Some are as tiny as your thumbnail. The biggest ones can stretch their arms wider than a car. And every single one of them is doing something most animals never do. They are thinking. Really thinking. So how much brain does a squishy bag of muscle actually have? The answer is going to surprise you, because it is not one brain. It is nine.
1:47Nine Amazing Brains
Yes. Nine brains. Here is how it works. An octopus has one main brain right between its eyes, like yours. But it also has a bundle of nerves in each of its eight arms, and each bundle works almost like a little mini-brain of its own. So when an octopus reaches into a dark crack in the rocks, that arm can feel around, explore, and grab something all by itself, without waiting for permission from the main brain. Imagine if your left hand could go find snacks in the kitchen while you were busy doing homework. That is octopus life every single day. In fact, more than half of an octopus's nerve cells are in its arms, not its head. Scientists sometimes say an octopus does not just have arms. It thinks with its arms. And that matters a lot for our mirror story, because when that octopus saw a crab in the reflection, its brain and its arms had to agree on a plan. But the arms have another secret trick, and this one involves taste.
2:43Suckers That Taste
Look at the bottom of an octopus arm and you will see rows and rows of little round suckers. A big octopus can have more than two thousand of them. Each sucker can grip, pull, and hold on tight. But they do something way weirder than that. Octopus suckers can taste. Not with a tongue. With touch. When an octopus arm brushes against a rock, it instantly knows if a crab walked over that spot recently, just from the chemicals left behind. So imagine walking barefoot across your living room and being able to taste that someone ate popcorn there yesterday. That is an octopus every second of its life. This is why an octopus can find food inside a dark hole it has never looked into. Its arms taste their way around. Now hold that thought, because in the mirror experiment, the crab was too far away to touch. The octopus could not taste it. It could not feel it. It had only one tool left. Its eyes. And octopus eyes are the strangest eyes in the sea.
3:39Colorblind Camouflage
Here is a fact that makes scientists scratch their heads. Most octopuses are colorblind. They almost certainly cannot tell red from green the way you can. And yet, an octopus is the greatest quick-change artist on the planet. In less than a second, it can turn from sandy beige to bright red to speckled brown, and match the exact pattern of the rock it is sitting on. How can an animal copy a color it cannot even see? Scientists think the answer might be hiding in the skin itself. Octopus skin is packed with light-sensitive cells, the same kind of cells found in eyes. So there is a real possibility that an octopus sort of sees with its whole body. Imagine your elbow noticing that the wall behind you is blue. Under the skin are millions of tiny colour sacs called chromatophores, and each one is squeezed open or shut by tiny muscles. Millions of them. All at once. But camouflage is only half the trick, because octopuses can change their shape too.
4:35The Shape Shifter
An octopus does not just change colour. It changes texture. It can push up little bumps and spikes on its skin so it feels rough like coral, or go smooth like a pebble. It can flatten itself into a pancake, or bunch up into a ball, or stretch out long and thin like a piece of seaweed drifting in the current. There is one kind of octopus in Indonesia, the mimic octopus, that copies other animals completely. It can flatten out and ripple along the sand like a flat fish. It can tuck six arms away and wave the other two to look like a very unfriendly sea snake. Scientists have counted more than a dozen different impressions in its act. It is basically an ocean comedian with a costume for every occasion. All of this shape-shifting takes serious brainpower, because the octopus has to look at its surroundings, decide what to copy, and do it in under a second. Now, if an animal is that clever about being seen, what happens when it looks at itself?
5:28How Mirrors Work
Before we get to the big experiment, you need to understand what a mirror actually is, because a mirror is honestly a little bit magical. Light is bouncing around you all the time. It leaves the sun or a lamp, hits an object, and bounces off in every direction. Some of that bounced light lands in your eyes, and that is how you see anything at all. A mirror is just an incredibly smooth surface, usually glass with a thin layer of shiny metal behind it. Because it is so smooth, light does not scatter in all directions when it hits. It bounces back in a neat, tidy way, like a ball off a flat wall. Your brain assumes light travels in straight lines, so it thinks the light came from behind the mirror. That is why your reflection looks like it is standing inside the glass. Here is a wow-fact. A mirror is not really flipping you left to right. It is flipping you front to back. Your brain does the rest. And brains, as we are about to see, get fooled by this a lot.
6:22Animals Versus Mirrors
Now here is the funny part. Almost every animal on Earth is completely bamboozled by mirrors. Put a mirror in front of a cat and it will often puff up and hiss at the imaginary stranger. Birds sometimes chirp at mirrors for hours. A dog might bark at itself, then run behind the mirror to find the other dog, and look genuinely offended when nobody is there. This is not because animals are silly. It is because using a mirror correctly needs a special kind of thinking. You have to understand that what you are seeing is not a real object sitting behind the glass. You have to understand that it is information about something in the real world, and that the real thing is somewhere else entirely. That is a big mental leap. Scientists call the ability to use reflections to find hidden things mirror-guided behaviour, and only a small handful of animals have ever shown it. Elephants. Some apes. A few clever birds. And now, maybe, an animal with no bones at all. Let us go inside that laboratory.
7:20Inside The Lab
Picture the lab. It is quiet. There are big glass tanks with cool, clean seawater, gentle lights, and hiding caves made of smooth rock so the octopuses feel safe and comfortable. Scientists who study animals take care of them very carefully, because a stressed animal cannot show you what it can really do. Happy octopuses get toys, puzzles, and plenty of space. In this study, three octopuses took part. Just three. That sounds like a small number, but octopuses are tricky to work with. They are quick to get bored, and they have a habit of solving your experiment in a completely different way than you planned. One scientist joked that testing an octopus is less like running an experiment and more like negotiating with a very slippery lawyer. The team built a special setup. On one side, a barrier the octopus could not see past. On the other side, a mirror angled just right, so the only way to spot what was behind the barrier was to look at the reflection. Then they added a crab. And they hit record.
8:18The Clever Crab
Now, a quick word about the crab, because I know somebody is worried about it. Octopuses eat crabs. That is just how the ocean works, the same way a robin eats worms and a cow eats grass. Every animal has a job in the food chain, and crabs are the octopus's favourite dinner. Crabs are pretty impressive themselves, by the way. They have ten legs, eyes on little stalks that can swivel around, and a hard shell that works like a suit of armour. They walk sideways because of the way their leg joints bend, which is honestly a very efficient way to move. And a crab can regrow a leg if it loses one. Some crabs can even taste with their feet, just like octopuses do with their suckers. So this was a genuinely fair contest. A shell-covered, armoured, sideways-scuttling snack, versus a boneless genius with nine brains and a mirror. Who do you think worked it out first? Let us watch the very first octopus take its turn.
9:11The First Octopus
Octopus number one comes out of its den. If you have never seen an octopus move, it looks like liquid deciding to go for a walk. It flows. It pours. Its arms feel ahead, testing the ground, while the rest of the body glides along behind. It reaches the open part of the tank and stops. Now, at this exact moment, the crab is behind the barrier. The octopus cannot see it. It cannot taste it. It has no idea food is nearby. Then something catches its eye in the mirror. A small movement. A flicker. The octopus freezes. Its skin ripples, and the pupil in its strange eye shifts. And here comes the wow-fact of this scene. An octopus's pupil is not round like yours. It is shaped like a wide letter W, and it can stay perfectly level even when the octopus tips its whole body sideways. It is like having built-in camera stabilisation. So this animal has just seen something impossible. Food, in a place where food should not exist. What does it do?
10:07Turning Away
Here is what a confused animal would do. It would go to the mirror. It would touch the glass, push at it, maybe try to grab the reflection, and then get frustrated when its arms hit a hard flat surface. That is what a cat does. That is what a bird does. That is what almost every animal on Earth does. But this octopus did something different. After watching the reflection for a moment, it turned. Not toward the mirror. Away from it. It moved around the barrier, in the direction where the real crab actually was, and it went straight there. Think about what has to happen inside a brain for that to work. The octopus has to see the reflection. Understand that the reflection is not the crab. Work out where the real crab must be, in a place it has never looked. And then commit to a plan and move. That is several steps of thinking, chained together, in an animal that separated from our family tree more than five hundred million years ago. But one octopus could be a fluke. That is why there were three.
11:05Octopus Number Two
Octopus number two takes its turn. This one is a bit bolder. It comes out faster, arms swirling, curious about everything. It spots the reflection almost immediately. And here is the thing scientists love to see. It does not repeat octopus one's exact moves. It has its own style. It hovers. It shifts position a little, as if checking the reflection from a different angle, the way you might tilt a car mirror to see more of the road. And then it commits, moving around the barrier toward the real crab. Different personality. Same solution. And yes, octopuses genuinely do have personalities. Researchers who work with them will tell you that one octopus will be shy and hide all day, while another will squirt water at anyone wearing a lab coat it does not like. There are recorded cases of octopuses learning to recognise individual humans by sight and treating them differently. So if you think all octopuses are the same, an octopus would strongly disagree. But it is octopus number three that gives us the most interesting moment of all.
12:08The Careful One
Octopus number three is the careful one. It comes out slowly. It sees the movement in the mirror, and then it does something wonderfully human. It checks. It reaches toward the mirror once, touches the flat cold glass, and pulls back. You can almost hear it thinking, nope, nothing there. Then it turns and heads around the barrier to the real crab. That little test is a big deal, because it looks like learning happening live. The octopus gathered information, ruled out the wrong answer, and switched to a better plan. That is exactly what a good scientist does. Try something. It does not work. Do not sulk about it. Use what you learned and try the smarter thing next. All three octopuses ended up at the real crab. Three out of three. And here is a wow-fact to hold onto. Octopuses can learn just by watching another octopus do something once, which is a kind of learning many animals with backbones never manage. So, three successes. But a good scientist is never satisfied with three successes. A good scientist gets suspicious.
13:08Testing For Tricks
Why suspicious? Because there are always sneaky explanations, and a real scientist has to hunt them down before celebrating. Maybe the octopus smelled the crab. Maybe it heard the crab moving. Maybe it just happened to wander in the right direction and got lucky. Maybe it always goes left. So scientists do something called a control test. That means running the same experiment again, but changing one single thing, to see if the result changes too. In this case, take the mirror away. Everything else stays exactly the same. Same tank. Same barrier. Same hidden crab. If the octopuses still find the crab without a mirror, then the mirror was never the reason, and the whole exciting story falls apart. This is my favourite thing about science. Scientists spend enormous effort trying to prove themselves wrong. Not because they want to be wrong, but because if an idea survives every attempt to knock it down, then you can actually trust it. So what happened when the mirror disappeared?
14:04The Mirror Matters
Without the mirror, the octopuses did not head straight for the hidden crab. They wandered. They explored. They searched around the way any hungry animal would when it has no clue where dinner is. The confident, direct beeline was gone. And that is the piece that turns a fun story into real evidence. The only thing that changed was the mirror. So the mirror must have been giving them the information. The reflection was not a toy. It was a map. Now, scientists are careful people, so they would say something like, these results suggest that octopuses may be capable of using reflected information to locate unseen objects. That is science-speak for, wow, this looks amazing, and we want to test it more before we shout about it. Three animals is a small group. Other researchers will want to repeat it with more octopuses, in different tanks, with different setups. That is not a criticism. That is how knowledge gets built, one careful brick at a time. But why is this such a huge deal for scientists? The answer is about a brain that is nothing like ours.
15:06Two Kinds Of Minds
Here is what makes this so exciting. Go back in time about five hundred and fifty million years, and you would find a small, simple creature that is the shared ancestor of you and every octopus alive today. After that point, our family lines split and never came back together. Our ancestors built a spine, a skull, and a brain packed into a head. The octopus line built no bones, blue blood, and a brain spread out through its arms. Two completely different designs. And yet both designs ended up doing something we call intelligence. Solving puzzles. Remembering. Planning. Using information about the world in flexible ways. Scientists call this convergent evolution, which is a fancy way of saying that nature found the same good idea twice, by two totally separate routes. It is like two inventors on opposite sides of the world building a bicycle without ever meeting. So an octopus is probably the closest thing to an alien mind that you can visit here on Earth. And speaking of blue blood, let me explain that, because it is fantastic.
16:07Three Hearts Blue Blood
Your blood is red because it carries oxygen using iron. Octopus blood is blue because it carries oxygen using copper instead. Copper-based blood is not as speedy as ours in warm water, but it works brilliantly in cold, low-oxygen ocean water, which is exactly where a lot of octopuses live. And to push that thick blue blood around, an octopus needs three hearts. Two of them pump blood through the gills to pick up oxygen. The third pumps it around the rest of the body. Here is the funny bit. When an octopus swims, that third heart actually stops beating. Swimming genuinely exhausts them, which is one reason most octopuses would rather crawl along the seabed than swim anywhere. So the next time you feel tired after running around, remember there is an animal whose heart just gives up and takes a break. Three hearts, nine brains, blue blood, two thousand tasting suckers and skin that might see light. And all of that equipment was used, in that lab, to solve a mirror puzzle. So how good are those famous eyes, really?
17:06Eyes Without Blind Spots
Octopus eyes are surprisingly similar to yours on the outside. There is a lens, a pupil, and a retina at the back that catches light. But they are built in a different order, and here is the amazing result. You have a blind spot. Right now, in each of your eyes, there is a small patch where you genuinely cannot see anything, because that is where the nerve wires bundle together and pass through the back of your eye. Your brain quietly fills in the gap, and you never notice. Octopuses do not have that problem at all. Their wiring runs behind the retina instead of through it, so they have no blind spot whatsoever. Nature basically got a second try at building an eye and did a slightly tidier job. Octopus eyes are also brilliant at spotting movement and detecting the direction light is travelling, something human eyes cannot do. That skill might be exactly what helped them notice a crab shimmering in a reflection. And once they see prey, the way they move is unbelievably sneaky.
18:03Jets And Ink Clouds
Octopuses have two ways to travel. The slow way is crawling, using those arms to grip and pull themselves along, quiet as a whisper. The fast way is jet propulsion. The octopus fills the space inside its body with water, then squeezes it out through a flexible tube called a siphon. Whoosh. It rockets backwards. And because the siphon can swivel, the octopus can point itself in almost any direction, like a tiny living spaceship. The very same siphon does another job. If a hungry shark shows up, the octopus can release a cloud of dark ink and jet away while the shark is confused. Here is the clever part. The ink is not just a smokescreen. It contains chemicals that mess with a predator's sense of smell, so it is a bit like throwing a fog machine and a stink bomb at the same time. Some octopuses even shape the ink blob so it hangs in the water roughly octopus-shaped, and the predator grabs the fake while the real one escapes. That is a magic trick performed by a mollusc. But the cleverness goes further still.
19:04The Coconut Carrier
Off the coast of Indonesia, divers filmed something that changed how people think about animal minds. A small octopus, about the size of your hand, was carrying two halves of a coconut shell across the sandy seabed. It walked on stiffened arms, awkwardly, like a person carrying a stack of plates that is far too tall. Then, when it decided it had gone far enough, it snapped the two halves together and hid inside, like a little armoured house. Why is that so important? Because the octopus was not using the shell right then. It was carrying it because it might need it later. That is planning ahead. That is what we call tool use, and it puts the coconut octopus in a very exclusive club alongside crows, chimpanzees and dolphins. Octopuses have also been filmed stacking rocks to build doors for their dens, and squirting water at annoying bright lights until the lights stop working. So this is an animal that plans, builds, and occasionally files complaints. Now let us talk about the puzzle boxes.
20:01Puzzle Solving Genius
In aquariums all over the world, keepers give octopuses puzzles to keep their busy brains happy. The classic one is a clear jar with a tasty crab inside and a screw-on lid. Most octopuses figure it out. They wrap their arms around the jar, grip the lid with hundreds of suckers, and twist. Some manage it in minutes. Then keepers make it harder. A jar inside another jar. A lid that opens the other way. A box with a latch. And the octopuses keep solving them, getting faster each time, because they remember. Here is the wow-fact. Octopuses have two kinds of memory, short-term and long-term, just like you do. They can remember a solved puzzle weeks later. Some aquariums have had to invent new puzzles because the octopus got too good at the old ones and started looking bored. Imagine being so smart that the staff have to redesign your homework. So when three octopuses cracked a mirror puzzle, it fit a pattern people had been noticing for years. But there is one enormous question this experiment does not answer.
21:03Do They Know
Using a mirror to find lunch is one thing. Looking in a mirror and thinking that is me is something else entirely. Scientists test this with a famous experiment called the mark test. They put a small harmless dot of paint somewhere on an animal where it can only be seen in a reflection, then watch what happens. If the animal looks in the mirror and then touches the spot on its own body, that is a hint it understands the reflection is itself. Only a handful of animals have passed. Great apes. Elephants. Dolphins. Magpies. And even then, scientists argue about what passing really means. For octopuses, the honest answer right now is that we do not know. The mark test is tricky for an animal that changes its own skin colour constantly and might not care about a dot at all. So the mirror-and-crab study shows octopuses can use reflections as information. Whether they know that the octopus in the glass is them is still an open question. And open questions are the best part of science, because somebody has to answer them. Maybe you.
22:04Science Done Kindly
Let us talk about how scientists actually did this kindly, because that matters. The octopuses were not tricked or frightened. They were offered a puzzle with a reward at the end, and they could choose to take part or go back to their den and ignore the whole thing. That is the modern way to study clever animals. You do not force them. You make the experiment interesting enough that they want to play. Researchers also spend weeks just letting an octopus get used to a tank before testing anything, so it feels relaxed. They check water temperature, salt levels, and light. They give octopuses hiding caves, because in the wild an octopus spends most of its day in a den. And when a study finishes, the animals are looked after carefully. Being a good scientist means being curious and kind at the same time. Those two things are not opposites. In fact, the kinder the setup, the better the science, because a comfortable animal shows you what it can truly do. So what happens next in this story?
23:02What Comes Next
Next comes repetition. Other research teams around the world will read this study and say, interesting, let us try it ourselves. They will use different species of octopus, different tank shapes, different mirror angles. They will try tilting the mirror so the reflection appears somewhere unexpected. They will test whether an octopus can use a reflection to find a hidden hiding place, not just food. Every one of those tests either strengthens the idea or reveals a crack in it. This is the part of science that never makes the headlines but matters the most. One study is a clue. Ten studies that agree is knowledge. Here is a wow-fact about how much we still have to learn. Scientists believe there are around three hundred known species of octopus, and new ones are still being discovered, including some living in the deep dark ocean where sunlight never reaches. There are octopuses down there brooding their eggs for over four years without eating. Four years. The ocean is full of stories nobody has told yet. And you can start noticing things too, right now.
24:02Mirror Challenge Time
Here is your first fun challenge, and it is completely safe. Grab a mirror, or use one already fixed to a wall, and stand so that you can see something behind you in the reflection. A door. A clock. A person walking past. Now, without turning your head, point to where that thing really is in the room. Not where it looks like it is in the glass. Where it actually is. That little brain-flip you just did is exactly what those three octopuses managed in the tank. Try it again with your eyes closed first, then open them and check. You can make it a game with a family member. One person hides a soft toy somewhere behind you, and you have to find it using only the mirror. No peeking, no turning around. It sounds easy until you try it, and then you will realise how much work your brain is doing. And here is a second experiment, one that shows you something about mirrors that most grown-ups get wrong.
24:53The Mirror Illusion
Stand in front of a mirror and raise your right hand. Your reflection appears to raise its left. So people say mirrors flip left and right. But wait. Why do they not flip up and down too? Your reflection's head is still on top, and its feet are still on the bottom. If a mirror really swapped left and right, why does it not also stand you on your head? Here is the answer. The mirror is not flipping left and right at all. It is flipping front and back. Your nose, which points toward the mirror, becomes a nose pointing back at you. Everything else stays put. It is your brain that tries to make sense of it by imagining you turned around, and that imaginary turn is what creates the left-right confusion. Try holding up a page of writing to a mirror and watch the letters go backwards. Then try writing your own name backwards so it reads correctly in the glass. That is exactly what artists and inventors have done for centuries. Your brain is doing something genuinely tricky, and now you know why.
25:50The Real Lesson
Now think about how much this one small experiment connects to. Light and how it bounces. Brains and how they build a picture of the world. Evolution and how the same clever idea can appear twice on the same planet. And the simple, powerful habit of testing your ideas instead of just believing them. That is the real lesson of the octopus and the mirror. The octopus did not have a bigger brain than a shark. It did not have better eyes than an eagle. What it had was flexibility. The ability to take strange new information and do something useful with it. And here is the wonderful news. That is a skill you can practise. Every time you see something confusing and think, hang on, why does that happen, you are doing the same thing that octopus did in the tank. Curiosity is not something you either have or do not have. It is a muscle. Use it and it grows. Let us pull all of this together, because you have learned a genuinely impressive amount today.
26:44Everything We Learned
Let us recap the greatest hits. Scientists gave three octopuses a mirror and hid a crab where they could not see it. All three used the reflection to work out where the real crab was, and went around the barrier to find it. When the mirror was taken away, the direct route vanished, which is how we know the mirror was doing the work. Along the way you learned that an octopus has three hearts, blue blood made with copper, and nine brain centres, one main one plus a mini one in every arm. You learned its two thousand suckers can taste by touch. You learned it is probably colourblind but might sense light with its skin. You learned it has no blind spot, a W-shaped pupil, and can squeeze through a hole the size of its own eyeball. You learned about a coconut-carrying octopus that plans ahead, and jar-opening octopuses that remember solutions for weeks. Not bad for an animal with no bones at all. But there is one last thing I want you to take away.
27:38Your Turn Explorer
The octopus in that tank did not know it was in an experiment. It just saw something odd, got curious, tested an idea, learned from the result, and found its lunch. That is the whole recipe for figuring out absolutely anything. Notice. Wonder. Test. Learn. Try again. You already have everything you need to do that, and unlike the octopus, you get to ask questions out loud. So here is your mission for today. Find a mirror at home and play the reflection game we talked about, pointing to where things really are instead of where they look. Then share one octopus fact at dinner tonight. My personal favourite is that an octopus's third heart stops beating whenever it swims, so swimming genuinely tires it out. See whose face does the best surprised expression. Thank you so much for exploring with me. The ocean is enormous, mostly unexplored, and absolutely stuffed with animals doing things nobody expected. Keep looking closely at the world. Keep asking why. And I will see you on the next adventure.
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Series: science (English)