Jumping Spiders Shouldn’t Be This Smart

A small spider begins its day asleep, nestled inside its web hammock, a tiny bed it's spun from silk. And here it looks like the spider does something scientists thought only vertebrates can do. Something characterized by muscle twitching, eye movements, and memory consolidation, REM sleep. This is the first hint that what we're looking at is not a typical invertebrate. This is a jumping spider, and inside of its head is a brain the size of a poppy seed, a cluster of a few hundred thousand neurons packed into a space barely a millimeter across. A mouse brain, for comparison, has 70 million neurons. And somehow, some way, scientists think this tiny brain is one of the most capable in the invertebrate world. People have sensed this for a long time, especially the people who keep jumping spiders as pets. They are loved not just because they look like Pixar invention, it's because they have big personalities and a level of awareness you just don't see in other creatures this small. And this isn't just a layperson's impression. Science agrees. They can jump far, yes, but they also jump with extreme precision. They're able to learn more quickly than much larger animals, vertebrates even, like pigeons. Some can even plan routes, keeping a detailed mental picture of their goal even when it's no longer in sight. They can recognize other spiders as individuals, as rivals, mates, or familiar neighbors. And some species perform one of the most elaborate and beautiful courtship dances known in the animal kingdom. And astonishingly, jumping spiders might even have an inner world, a world that they dream about every night. I had hoped to find one in the wild that I could show you in this video, but at the time of writing this, it's February in New England. I figured I was going to have to wait until summer to find one in the woods and release this video much later. But to my complete surprise, the other day, I found one. In the middle of a blizzard. I was clearing a path for my dog in the two feet of snow we just got, and excavated an old dog bowl that had been sitting upside down here and buried for who knows how long. And there it was. It's hard to see, but it's there. Asleep, curled inside its hammock. Maybe even dreaming. So how can such a small spider with such a small brain be this smart? Why does it seem so different from other spiders? How do scientists even measure intelligence in an animal like this? And in what ways can these tiny predators rival or even surpass animals with brains many times larger? Of the 50,000 known species of spiders, jumping spiders make up about 6,000 species. They're small, hairy spiders with compact bodies and short, sturdy legs, and are found on every continent except Antarctica. And even within this group, there is a huge amount of diversity. Some, like Porsche spiders, are relatively large and feed on other spiders. Other jumping spiders are smaller. Some are cuter. Some less cute. Some even mimic other dangerous things like ants or scorpions. Some have colors so vibrant it's hard to believe. Others camouflage remarkably well. The largest species, aptly called the giant jumping spider, can grow to be about an inch or 2.5 centimeters long, which is still not that big. And the smallest known species of jumping spider is Neonella vanula, which is almost impossibly tiny, with adults measuring about 1.5 millimeters long. This one's brain would be microscopic. The one I found is extremely small. I think it's a bronze jumper. It's so small that I had trouble filming it. I don't have a macro lens. But with some magnifying glasses and a phone, we can still get a decent look. In the past, before working on this video, I never would have noticed its tiny little silk hammock on the side of that bowl. And if I had seen it crawling in my house, I wouldn't have known that it's one of the coolest animals on the planet. But even a spider this small is a terrifying predator. If you are also very small, that is. Because jumping spiders don't hunt by trapping prey in their webs like we think most spiders do. Instead, they are ambush hunters. Once a spider spots a prey animal, like a fly for example, it will stop and freeze, keeping its eyes locked onto target. Then, slowly, the spider starts to creep and its body lowers. Then, when the moment is right, it launches. The jump itself is powered primarily by the rear legs, especially the fourth pair of legs, which provide most of the thrust. Unlike vertebrates that use muscles, the jump is driven largely by hydraulic pressure. The spider rapidly increases internal fluid pressure to extend its legs explosively. The front legs are not used for propulsion. Instead, they are held forward during the leap and are the first to contact the prey. These legs help grab, pin, and stabilize the insect on landing. Almost simultaneously, the spider delivers a venomous bite to subdue the prey. If this feels familiar, it's because this is a lot like how cats hunt. Not the venom or hydraulics, obviously, but everything else. And making this even more incredible is that the spider doesn't necessarily jump at the prey. In some rare cases, it seems that they can leap through the air towards the point it has calculated that the prey is going to be, not where it is now, enabling the spider to snatch the prey out of mid-air. But how deliberate are these jumps really? Are they just flinging themselves and hoping for the best? A 2018 study gives us a hint. Researchers used high-speed video to record and analyze the jumping behavior of a regal jumping spider across a range of jumping challenges. Each jump had a different distance or different elevation. They measured the kinematics of each jump and found that the takeoff angle and body posture changed depending on the distance and elevation of the gap in front of it. You can see it easily. Look at this jump, a short horizontal jump. The spider uses a lower takeoff angle to minimize flight time. Now look at this longer jump. The spider uses a steeper angle, something that saves energy. And the farther the jump, the steeper the angle. It's clear that the spider is calculating its jump in advance, rather than leaping randomly. Some species can jump distances a few times larger than their body length, and some many, many times their body length. For at least one species, Colonis puerperis, there is a documented horizontal jump of 23 centimeters from a male spider about 6.2 millimeters long, i.e. 38 times its body length. This is especially impressive considering jumping spiders usually start their jump from a stationary position, no lead up or running to get momentum. And there's something else you can see in some of these videos, the spider's dragline. It's an area of ongoing investigation, but scientists think draglines might be used to adjust the spider's mid-air trajectory by allowing them to control rotation and direction as they jump. The tension in the silk might slightly pull or correct its path, and this silk is really tough. But how does it rank with the other spiders? For a long time, scientists thought orb weaver silk was the toughest natural material on earth. The silk from Darwin's bark spider has long held the top rank for toughness. It's a spider that builds some of the largest webs on earth, often over a meter wide, but sometimes spanning over 25 meters. But a 2021 study found that the silk of zebra jumping spiders rivaled the toughness of Darwin's bark spider and exceeded the vast majority of all other orb weavers. This sounds kind of impressive, sure, but what makes it mind-blowingly impressive is that jumping spiders make this silk dozens of times faster than orb weavers. Normally when a material is produced very quickly, the internal molecules don't have time to align neatly, so you get more disorder and defects. The result is usually weaker, less tough material. But jumping spiders break this rule. They evolved a way to maintain molecular order at extreme speeds. And this toughness is important, because in case the spider misses its target or falls, that silk line acts like a rock climber's safety rope. But the thing is, a jumping spider rarely misses. So how exactly is this tiny predator measuring the distances so accurately? The answer starts with its eyes. When thinking about animal vision, there's usually a simple rule. Bigger eyes means finer detail. This is a chart that shows it as a clear trend. As eye size increases, visual acuity increases too. A simple upward line. Most insects sit low on that line, limited by compound eyes, while larger animals climb higher with birds of prey at the very top. But jumping spiders break this pattern. They sit far above the curve, seeing with a level of detail that their tiny eyes shouldn't allow. They're better than rats. They're better than most fish. As good as an elephant. How is this possible? Jumping spiders possess several pairs of eyes. There are the huge ones at the front, and then there are three pairs cascading down their head. Do these eyes provide redundancy, or do they all do different things? A 1928 study investigated this question using a particularly cute technique, tiny little eye patches. Normally when a jumping spider detects motion, it will spin its body to orient its principal eyes to that moving object. But when scientists blocked the posterior lateral eyes and moved an object behind a spider, the spider didn't turn towards the moving object. When the scientists blocked the posterior median eyes and moved an object above the spider, the spider didn't reorient itself. And when scientists blocked the anterior lateral eyes and moved an object towards the front, they reacted more slowly. This showed that each set of these secondary eyes detects motion in a specific part of a nearly 360-degree visual field that wraps around the spider like a dome. But conversely, when they covered the anterior median eyes, the large forward-facing ones, the spiders could see the motion, but couldn't seem to fixate precisely on objects. They knew something was there, but they couldn't examine it well. This showed that the secondary eyes detect motion, and the principal eyes analyze it. I saw this myself. When I gently moved a stick into the spider I found's field of view, it didn't react immediately. First it noticed something with its peripheral eyes, then slowly it turned its body, aligning its large forward-facing eyes with the object, locking on, inspecting it. So you can kind of think of the secondary eyes giving them the scene, essentially in black and white, and then these principal eyes moving around, filling it in with color and pattern, any place that they might be interested in looking. To understand more about jumping spider vision, I spoke with Dr. Nathan Morehouse, Associate Professor in the Department of Biological Sciences at the University of Cincinnati and expert in spider vision. The secondary eyes are what we would call simple eyes. I dislike that name because it makes them sound simple and they're not. Our eyes are simple eyes. You can also call them camera eyes. The idea there is that basically they have a lens, often with a little bit of a clear space between the lens and the retina, but the retina is a sheet of photoreceptive cells, and so they really do work like a camera, right? You know, they've got a lens and then you've got a sensor or a piece of film or whatever. But the principal eyes are built very differently from that, and they are widely considered the most sophisticated eyes relative to their size in the animal kingdom. These eyes are not round, but long and tubular, basically like small telephoto lenses. And the first weird thing about them is that they have two large lenses. And so what that does is it takes the image that that first lens focuses down the tube and it blows it up onto the underlying retina. So that already helps these animals improve their ability to see pattern and detail in the world. But it gets weirder. But then underneath that lens system is a retina, but it's not a sheet of cells, it's layers of cells. And parts of the field of view of that retina have four sets of cells stacked on top of each other. And that does a bunch of things for them. One, it allows them color vision because the cells and different layers are typically sensitive to different wavelengths or colors of light. Retina stacking also gives them sharper vision. Lenses naturally focus different wavelengths of light at different depths, which can blur color vision. This is called chromatic aberration. But the jumping spiders stacked retinal layers align each type of light like UV or green light exactly where it comes into focus. And interestingly, because of this unusual structure, these spiders likely only need one eye for depth perception. And the way they do that is by comparing how in focus something is in the bottom two tiers of the retina. Because objects at different distances will be more in focus in one of those tiers than in the other, they can use the difference in focus to evaluate how far away something is. It's something called depth via defocus. But as sophisticated as these eyes may be, they are not without their own challenges. As any photographer knows, a telephoto lens is great for sharpness and seeing at a But they have a very narrow and fixed field of view, and the spiders can't move their eyes around like we can. They compensate for this partly by moving their bodies around to get a better look at something, but they also do something else extremely weird and cool. They can move their retinas. This spider is so transparent that you can actually see it happening. They are able to move the retina around inside the head, swung on that long tube, which is flexible, powered by six muscles attached to the back of the retina and then to the body. And it allows them to swing it left and right and up and down and of course at angles, but also it allows them to twist it for reasons that we don't fully understand yet, but that might allow them some additional visual capabilities. So they essentially have a movable fovea. So it's not their whole eye that moves like ours do, but rather the parts within the eye. It's really interesting because these are all really cool solves, like engineering solves in a certain way for challenges that an eye built like this might face. And they use their little legs to keep their eyeballs clean. With these eyes all combined, over the course of evolution, these spiders became elite predators, and the need to spin a web to catch prey disappeared. An ambush predator with incredible vision doesn't need a passive trap, but hunting with their eyes added some increased pressure. They had to start making decisions. They had to choose which prey is worth the energy, decide when to strike, and plan how to approach. So in this new world, the spiders needed the computing power to make that possible. An intelligent spider was born. Intelligence in animals is fun to think about and compelling to witness, but measuring it is actually not straightforward. There's no single intellectual scale by which to measure animals. However, there are certain things that can be tested. Things like an animal's ability to learn. A 2013 study did exactly this with the fence post jumping spider, using an experimental technique called reversal learning. Reversal learning experiments are a simple way scientists test how flexible an animal's thinking is. They test whether an animal can let go of an old rule when it stops working. In one experiment, researchers presented spiders with two drops of water, one blue and one yellow. The blue drop on the left contained sugar, a tasty reward. The yellow drop on the right contained citric acid, something spiders strongly avoid. After a short time, the spiders learned the rule, blue on the left means food. But then, the researchers reversed it. So now the blue drop contained citric acid and the yellow one had sugar. At first, the spiders naturally approached the blue droplet, seeking their treat. They instead got a sour shock. If a spider kept choosing blue again and again even after this first shock, that would suggest rigid, habitual behavior. But that's not what happened. The spiders adapted almost immediately. 10 out of 12 spiders chose correctly on the very first trial after the reversal. There was no extended period of trial and error, no gradual improvement over multiple attempts. The spiders behaved as if they noticed that the world had changed and updated their expectations right away. This all looks a lot like flexible learning. Certain larger animals with much larger brains often can't achieve what the jumping spiders did. Pigeons, for example, have brains millions of times larger than a jumping spider's. Yet in classic visual reversal learning experiments, pigeons often kept choosing the old option again and again, sometimes for dozens of trials, even when it no longer produced a reward. This doesn't necessarily mean they're stupid, they're just relying heavily on reinforcement history. Once a habit forms, it's hard to break. And conversely, this doesn't prove that jumping spiders are hyper-intelligent. It shows us that they use specific visual cues and can update their behavior very quickly. But we're not done, because a jumping spider's cognitive ability doesn't stop there. Jumping spiders prey on a variety of other small creatures, but for some species like those in the Porsche genus, one of their favorite prey items is other spiders. And hunting another predator like this is no easy feat. Other spiders who sit in their webs can detect vibrations, see movement, retaliate, or even kill the jumping spider if the approach is wrong. So instead of where's the prey, the jumping spider has to ask, how do I get there without being seen, without triggering the web, and without giving myself away? So often the most effective way to hunt the spider is not to reflexively pounce on it once it's spotted, but to strategize a flawless approach. This is where planning enters. A 2016 study showed just how able and willing spiders of the genus Porsche are to plan detours to attack prey. The researchers created a sort of complex apparatus full of paths and bridges zigzagging over a tray of water. Jumping spiders are known to hate water. The cat analogy is still going strong here. The spider emerged from a hole on an elevated tower and was able to see two boxes before it. Box A with nothing in it, and box B with its favorite meal, a wall spider. The boxes were way too far for the spider to leap to it. So to get to it, the spider would have to descend from its tower and go on a journey along the apparatus. But the problem was, once the spider left its tower, it could no longer see the prey. And when it got to a crossroads, it would have to choose which path to take, the correct path that eventually led back to the prey box, or the incorrect one that went nowhere. If the jumping spiders simply used instinct or random trial and error, it would sometimes head down the wrong path or wander aimlessly. But that isn't what happened. Across all 15 species tested, the spiders chose the correct path significantly more often than the incorrect one. This shows that they see the full problem ahead of time, evaluate the alternatives, and select the correct route before they even begin moving. It's behavior consistent with planning ahead, not reflexive wandering. This behavior only makes sense if the spider believes the prey continues to exist even when it's no longer visible. If the prey simply ceased to exist once out of sight, the spider would abandon its plan or wander randomly. One of the things that jumping spiders are able to do is see much, much farther away than they can do something immediately to react to. And so this capacity to plan and to find a route, etc., comes from the fact that they can see parts of the world that they can't act on right away. I don't think a lot of people appreciate, if they haven't actually spent time around those spiders, how kind of creepily slow they are about coming to these types of choices around their world. They spend a lot of time just lurking and watching while they, I think, are processing. They're essentially taking all of this information and then in very clever ways that we don't understand, simplifying it in a way that allows them to come to some kind of intelligent decision about what to do next. So much of jumping spider cognition seems to be related to their hunting strategy, finding, tracking, and subduing difficult prey. But that is not the only thing they look for using their great eyesight and remarkable brains. They're also looking for each other. For us and many vertebrates, seeing another member of our species isn't just about what they are, but about who they are. This is an ability we take for granted. Recognizing specific individuals of your own species is one of the most complex perceptual tasks in biology. It requires detecting subtle differences between individuals that often look nearly identical. Those differences can change over time with age, lighting, posture, or movement. And once detected, they have to be and accurately matched later, often using limited sensory information. We thought for a long time that only animals with large brains and rich social lives, like primates, birds, or dolphins, were able to do it. We thought that most small-brained animals didn't have the computing power and instead just relied on simpler strategies, like recognizing broad categories, like kin versus non-kin, or dominant versus subordinate, or potential mate versus rival. But a 2024 study challenged that assumption. Researchers designed an experiment that asked a simple question. Does a jumping spider treat a familiar individual differently from a stranger, even after time has passed? To test this, they took two regal jumping spiders, A and B, and exposed them to each other for seven minutes. During this time, they would walk towards each other and get acquainted. They were then visually separated for three minutes using an opaque barrier. Then, during the interlude, the researchers would either leave spider B in place or replace it with spider C. They would then remove the barrier and see how spider A reacted. And what they found was compelling. For the individuals the spiders had already hung out with, they weren't as interested. They kept their distance. For the new individual, there were clear signs of interest, like moving closer. The researchers then repeated the experiment with hours of separation instead of minutes, and the pattern remained. The spiders were more interested in the new guys, less interested in the original guys. And this pattern was extremely strong and statistically robust. So this implies that jumping spiders are capable of recognizing specific individuals, not just categories. This is incredible, but why they do this is still a little perplexing. From all we know, regal jumping spiders have a limited amount of repeated encounters with the same individuals in the wild. So is this all just a side effect of being kind of smart in general? Maybe, but the researchers of this study have a different idea. Sometimes in nature, territorial animals express reduced aggression towards familiar foes, while being extra aggressive towards completely new individuals. It's sort of a the devil you know effect. It's called the dear enemy phenomenon. The researchers of this study suggest this could be why the jumping spiders would have had the evolutionary pressure to evolve this type of cognitive capacity, to more easily coexist with rival neighbors. However, more studies would need to be done to know for sure. But nevertheless, this specific behavior is one of the main reasons we humans are so attracted to them. We don't know for sure that this ability translates across species for the jumping spiders, but people often say that their jumping spiders acknowledge them when they walk in the room, that they do this more so with their favorite people, that they are observant, that they are aware. Recognizing another individual is already a remarkable cognitive feat. But for some jumping spiders, it isn't enough to simply tell one member of their species from another. They have to ask the question, which one is worth mating with? For peacock spiders, the answer unfolds in one of the most elaborate dances on earth. With peacock spiders, you pretty much have a bird of paradise on a much smaller scale. This is Jürgen Otto, a photographer whose photos of peacock spiders launched them into the limelight for the first time in 2008. When he started photographing them, there were six known species. Now there are 106 and counting. Almost all of them live in Australia, some in New Zealand, and there might be one in China. The diversity is incredible, particularly if you look at all the different colors and patterns. And every time you find a new one, it's just a new, exciting time. When a new species is discovered, okay, you can see a little bit it's different from others, but you don't know exactly how different it is until you get the male to display. When I first came across Jürgen's website, my jaw hit the floor with just how many different peacock spiders there are. I had seen Meritus volans before and thought that was the only one, but I was so wrong. There are so many incredible peacock spiders, each one of them with incredible colors and patterns. If you ask a human to come up with patterns, he wouldn't come up with any of these ones. They're sort of out of a different world. And not only do their colors differ, so does their behavior. Take Meritus volans, the best known peacock spider. At first, the male, you see how he gets excited and starts vibrating his body. Then he's putting up two legs into the air. The third pair of legs raises them. Then up come the flaps, and the spider walks from side to side. This dance is characterized by his brilliantly colored abdominal flap, revealing iridescent blues, reds, yellows, and blacks arranged in bold geometric patterns and leg motions that are highly patterned, with specific angles, pauses, and tempos. But then the others lose something very different. For example, there's a group of spiders that we call the Vespa group, where the male also uses his legs in a similar way, but he lets the female approach to a very close distance of two, three millimeters. And then he sort of puts in a show where he shows his flaps on one side maybe, and then lets them disappear again and puts them up on the other side. So he keeps the female constantly entertained, and the female constantly following the movements of these flaps. This is interesting because the female is at such close proximity that she could easily jump on that male and devour him if she wanted to. So the male's under constant pressure to perform. Another one that comes to mind is some species that lift the abdomen up while they're pushing themselves up on the legs and then can rotate the abdomen underneath the bodies to let the female see the underside of it. Some species don't have flaps at all and don't even bother to putting up the abdomen to show it because it's not particularly interesting, but they have a very blue face. That's Maratus personatus that I'm thinking of. And he just uses his legs, leg movements, and vibration of the body. There's Maratus tortoise, one of my favorite ones, who shows the female one side of the flap and then with a like swishing motion, shows her the other side and just keeps on doing it in close proximity to the female. And what's even more incredible is that each species doesn't just have a single dance, but a whole repertoire of different moves. Moves that are employed at different times of the courtship, but not always in the same sequence. Each of these moves probably has a specific purpose. And on top of this, a 2011 study documented that they also produce vibrational songs. The researchers found that males produce distinct repeatable vibration patterns by rapidly tapping and scraping the substrate with their legs and abdomen. You can The vibrational signals consist of short pulses, buzzes, and longer broadband components with dominant frequencies generally in the low hundreds of hertz, well within the sensitivity range of jumping spider mechanoreceptors. The female can't hear these sounds in the air, she feels them through the substrate. But aren't these sounds just a byproduct of their flashy movement? The scientists don't think so. The sounds still happen when the male spider isn't doing the best parts of and even when the spiders can't see each other. The authors conclude that females are likely evaluating males based on a combined signal, integrating vibratory information with visual cues. And the stakes in all of this are very high. The female is larger, unimpressed by default, and is perfectly capable of killing and eating him if the performance is wrong, or even if it's right, but poorly timed. But if he does this all correctly, he gets the chance to mate. This all absolutely blows my mind. Invertebrates court all the time, crickets sing, fireflies flash, moths release pheromones. But what makes the peacock spider different is the complexity of this. The signal is multimodal. Color, motion, timing, posture, and vibration are coordinated into a single performance. Plus, these dances can be anywhere from a few minutes long to an hour. This all fundamentally violates our expectations about simple animal minds. I definitely think there's a lot of cognition going on. If you watch their behavior, you see how constantly the male judges the reaction of the female and adjusts its behavior accordingly. This doesn't happen like a programmed thing. There's constant variation in it depending on each other's reaction. But weirdly, males will even dance for females that aren't even the same species as them. Can they not tell? Do they not care? Usually the females will ignore these males, but not always. Sometimes the females will watch, captivated. Could certain species even be capable of interbreeding? We don't know the answer to this, but it would be a fascinating line of inquiry for research. And look how freaking small it is! Sometimes watching the clips of these animals, I forget the scale. Even if you tell people how small they are, I keep telling people that between two and four millimeters, but it doesn't compute until they actually see them. And they're still surprised how small they are. This is one of the main things with peacock spiders, that any of this behavior that we recognize and observe would be sort of less astonishing if it was in a large animal, in a vertebrate. But seeing this in such small animals just is unbelievable for most people. They are so impossibly small for being this impossibly clever. If all of this so far has your imagination spinning, wondering about the inner worlds of these spiders, you're not alone. I can't help but wonder if they can form expectations, remember individuals, and solve problems. Then is there a subjective experience inside that tiny nervous system? Is there any way to ever actually know this? There probably isn't, not exactly, anyway. But it's really hard not to speculate. People who keep these spiders as pets have endless stories of moments that seem truly inquisitive. Like this spider that seems to be looking at his own reflection, pondering its own existence. I know I'm anthropomorphizing, but I also believe there's more going on here than we realize. A 2022 study begins to reveal just how mentally sophisticated jumping spiders might be. Scientists wanted to know whether these tiny predators don't just rest at night, but whether their sleep is structured in distinct phases like ours. To test this, researchers filmed young jumping spiders while they slept. They focused on juveniles because, unlike adults, their cuticle is still transparent. And remember how through the transparent cuticle we could see the spider's retinal movement? This little feature allowed the scientists to do something almost unheard of in an invertebrate, watch eye movement during its sleep. By filming sleeping juvenile jumping spiders, researchers could directly observe retinal motion between the cuticle and ask whether jumping spiders show a REM-like sleep state. For vertebrates, REM sleep is characterized by eye movement and muscle twitching. And sure enough, the spiders exhibited regular periodic bursts of retinal movement. These eye movements were rhythmic, consistent in duration and interval, and increased in length as the night progressed. These retinal movements were also tightly linked with muscle twitches and stereotyped leg curling actions, behaviors analogous to the twitching that we do during REM sleep. This is the first strong evidence of REM-like sleep in invertebrates. And this is mind-blowing because of what we know about REM sleep. For us, REM sleep plays a major role in stabilizing and integrating memories. Everything from emotional memories, to memories regarding new skills and patterns, to associative links between ideas. REM sleep seems to reorganize new information. It also works to regulate our emotions and build new neural pathways. And most fascinatingly, our most vivid narrative dreams occur during REM. One hypothesis about why they might be doing this is focused on a much larger concept of the function of dreams. My understanding of one of the functions of dreams is that it is a way of trying out models of the world, predictive models of the world, while avoiding the costs of them, right? So you can try out how your body would react to flying without needing to jump off a building, right? And you do this in your dreams so that your brain can be better prepared for the world when you're awake. We thought for a long time that this was exclusive to vertebrates, that dreaming probably didn't exist in the arthropods, the insects, the smallest small-brained creatures of our world. But the jumping spider challenges all of this. Perhaps it doesn't have to do with brain size. Perhaps it has more to do with an animal's visual system. I've heard some people argue that because they're such visual creatures, it could have something to do with consolidating the things they've seen during the day, like their memories. Yeah, I mean, they do have memory. We've been able to teach them to avoid or prefer particular colors in prey, and those memories seem to last for about two weeks. So it is possible that they are essentially updating their cognitive model of the world, reinforcing memories, or trying out new possibilities. It's not really clear. Does all of this mean that they are literally dreaming, seeing images, replaying fights with other spiders, feeling like they're jumping through molasses? Maybe, but we'll probably never know for sure. But all of this does suggest that vision is being processed offline, and that even tiny brains may need downtime to process the world. It's so hard not to anthropomorphize, but when you're around them, it's impossible not to. Yeah, I think it's fine. I mean, we do have in the Venn diagram of how we experience the world with jumping spiders, the part that's shared is probably very narrow, but we do share some of our world. And I think anthropomorphization has a bad rap for good reason, because we can over-apply it. But in reality, I do think that more of our world is shared with the perceptual worlds of other animals. So some of our instincts and intuitions there are probably not wrong. We just have to be cautious about it. This all leaves me with one final question. How do you get that much computing power in such a tiny little brain? It's the fundamental neuroscience question about jumping spiders. And the answer is really cool, and kind of complicated. And it was going to be hard to illustrate, and this video is already really long, and I was out of time. So rather than add a final segment to this video, I've written a short article that answers this question that you can read for free over on my Patreon. I'm going to use Patreon for regular updates about the channel and about my life, and any cool creature I might have found that day. Think of it like a free newsletter. You just have to join as a free member. And if you've ever watched my work and want me to be able to keep doing it, there are a few ways to help out financially. 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Signing up will be a massive support to the channel, and you'll get a collector's item that only 99 other people are ever eligible to receive. This is all a big experiment. The hat pins, the Patreon, but even the channel as a whole. I really want this to work. There's nothing I love more than teaching everyone about this world's creatures, its plants, and its ecosystems. We got the last channel to over 2 million subscribers and reached hundreds of millions of people. I'm holding out hope that we can achieve something great together again. The path might just be a little bumpy, a little difficult, a little emotional. But whatever happens, we will learn about some cool bugs along the way.