Dwarf Reedsnakes Roll at 3.7 m/s and Keep Their Heads Still

On a night in August 2019, a group of researchers surveying for other species in northwestern Malaysia came upon a small snake crossing a road. It was a dwarf reed snake, and it had noticed them too. What happened next was not what anyone expects from a snake. The animal threw its body into a coil and went rolling down the slope, over and over, until it was out of reach. The researchers had heard stories of this trick before, but nobody had caught it on camera.

Seven years later, a different team has finally worked out how the trick is done. Biologists from Toho University in Japan filmed dwarf reed snakes on a narrow racetrack, from several angles, and rebuilt their movements in three dimensions. The snakes reached 3.69 metres per second, about four times the top speed of their ordinary side-to-side crawl. They did it while keeping their heads pointed forward and at a steady height, even as the rest of the body was somersaulting. A wheel has an axle to keep its hub still. A snake has nothing of the sort, and yet this one behaves as if it did. The work appeared in Current Biology on 19 October 2026.

A snake that hides for a living

Dwarf reed snakes belong to the genus Pseudorabdion and live across Southeast Asia. They are small, slender and secretive. The species at the centre of the 2019 road encounter, Pseudorabdion longiceps, is typically a few tens of centimetres long at most, and the individual caught on camera in the first formal report measured about 25 centimetres. In Evan Quah's words, reed snakes are “semi-fossorial, secretive and generally nocturnal”: they spend their days in leaf litter or under logs, sand and rocks, which makes them very hard to find. Quah is a herpetologist at Universiti Malaysia Sabah. By day they are hidden; by night they come out, and then they are prey for birds and for other snakes.

That lifestyle explains why such a spectacular behaviour stayed out of the scientific literature for so long. Reed snakes are common in their habitats, but common is not the same as seen. Field guides mentioned the rolling, and it is very likely that people living near the forests had watched it. Scientists who study them simply had not had a camera running at the right moment. Ian Brennan, a reptile specialist at the Natural History Museum in London, put the lesson plainly when the first formal description appeared in 2023: local communities and Indigenous peoples know many things about their local plants and animals, and that knowledge has not always been valued scientifically, so there could be many behaviours that have not yet been written down.

The first recording: a snake on a road

The 2019 encounter became that first formal description. The surveyors startled the snake on the road, and, as reported by Smithsonian Magazine, it curled into a coil and began rolling downhill. They caught it, placed it on a flat area and brought out a camera. The snake rolled away again, this time without gravity's help. The report, by E. S. H. Quah, L. L. Grismer and M. S. S. Anuar, appeared in the journal Biotropica in 2023 and described the snake's cartwheel as a rare escape mechanism not formally documented in detail for any other snake or reptile.

The authors described a loop-and-launch sequence. The snake curls its body into an S-shape and uses its tail to push off the ground. In the air its body loops forward and the head touches down. The tail then comes over the head, and the snake rolls forward onto its body, after which the cycle repeats. By the museum's account, a snake of that size covered about 1.5 metres, six times its own length, in five seconds.

Quah and his colleagues also noted what the behaviour costs. Cartwheeling appears to be very metabolically taxing, Quah said at the time: the snakes cannot sustain it repeatedly or over long distances, so it is “a defence mechanism employed only under extreme duress”. The snake can also borrow help from the terrain. Downhill slopes give it a quicker start and keep the rolling going for longer. The authors suggested the behaviour might hinder predators in two ways, by startling or confusing them, and by leaving a patchy scent trail, because only a small part of the body touches the ground at any moment. They also suggested it may have grown out of simpler jumping and startle responses, which are known in several groups of snakes.

That was a single snake, observed by chance. A single animal can show that something is possible; it cannot say how typical it is, or how the body manages it. For that, someone needed several animals, a controlled setting and high-quality video.

Why a rolling animal is not a wheel

To see why the Japanese team found the head so interesting, it helps to think about what a wheel does. A cart wheel spins continuously around a fixed axle. Whatever the axle carries, the cart, the driver, the cargo, does not spin with it. The wheel turns; the load stays level.

Animals do not have an axle. If a creature rolls as one rigid body, everything on it rolls too, including the head and with it the eyes and the other sensory organs the animal uses to find its way. The study's authors point out that this makes it hard to adjust posture and to steer in the intended direction, and that the difficulty gets worse as speed increases. Anyone who has rolled down a grassy hill knows the feeling: the world turns upside down, and holding a heading is close to impossible.

Nature has plenty of rollers, and they mostly deal with this problem by avoiding it. Pangolins, hedgehogs, echidnas and armadillos curl into defensive balls. The Venezuelan pebble toad tucks in its head and tumbles down slopes to escape tarantulas. The Mount Lyell salamander coils into a wheel and bounces down steep rock. In Morocco, the flic-flac spider somersaults across desert sand, a tactic that Smithsonian Magazine says can take it to about 3.8 miles per hour but eats up enough energy that it can only be used in short bursts. In Namibia, a golden wheel spider cartwheels downhill. Mother-of-pearl moth caterpillars roll as well. But most of these animals rely on gravity and an incline. The snakes, Live Science notes, are unique among rollers in that they seem to have good control over their rolls.

Dwarf reed snakes do something different, which is why Jake Socha found the first video so hard to believe. Socha is a biomechanics researcher at Virginia Tech who was not involved in the study. His first question, he told the journalist Sabrina Imbler, was whether the video was AI-generated: “It's definitely real, and that's kind of why it's jaw-dropping. You don't expect that the animal can do that.” Other snakes and legless lizards can lift off the ground, he noted, since horned adders can use a striking motion to do it and some legless lizards jump. But those are one-off actions. A dwarf reed snake rolls in a continuous motion, again and again, and that, he said, is part of what makes it remarkable.

The racetrack in Borneo

Yosuke Kojima, a zoologist at Toho University and the first author of the new paper, heard about the behaviour from a colleague in Malaysia some seven years ago. When he first saw it himself, he said, he “was amazed by the dynamic movement and immediately wanted to learn more about it”. His team began observing rolling in the Malaysian state of Sarawak, on Borneo, around the time the 2023 team was making its own observations, and they filmed it repeatedly in three dwarf reed species between 2019 and 2022: P. saravacense, P. collaris and P. longiceps.

For the controlled experiments the researchers collected snakes in Kubah National Park in Malaysia, as reported by Smithsonian Magazine: eleven P. saravacense, one P. collaris and one P. longiceps, thirteen dwarf reed snakes in all. For comparison they also caught six reed snakes of another genus, Calamaria, which are bigger than the dwarf species. In the laboratory they set up a snake-sized racetrack with cameras recording from several angles. One at a time, each snake was placed at the start and given a gentle tap or nudge to see what it would do.

The outcome was clean. All thirteen dwarf reed snakes rolled. None of the six Calamaria did; they simply slithered down the track in the normal way. That contrast matters: it shows that rolling is not something any small snake will do when it is prodded, but a trait of this particular group.

Speed alone did not reveal the mechanism. The movements are too fast for the human eye to follow. Kojima told Imbler that he could see from slowed-down footage that the snakes kept their heads facing the direction of travel, “so they couldn't simply be rolling their whole bodies”, but he could not work out how the motion worked until he watched the videos over and over and mapped them out in three dimensions.

Anatomy of a stroke

What the reconstruction showed is a cycle with two parts. In the first, the snake rolls along the ground with one side of its body in contact with the surface. In the second, it swings a curved, arched section of its body down past the side of its head, toward the ground. The researchers call that swing a “stroke”. When the arch lands, it starts the next roll. And with every cycle, the side that touches the ground switches, and the stroke changes direction between left and right. Put enough of these cycles in a row and you get continuous forward rolling.

The Smithsonian's description of one cycle, based on the paper, gives a feel for the choreography. The snake begins by curling into a tight curve, with its head lifted off the ground and facing the way it is heading. As it rolls like a wheel, its body begins to straighten and the point of contact slides toward the tail. Then it pushes off with the tail and launches into the air. While airborne it twists into an S-shape, forming an arch above its head, and swings that arch forward and down past one side of the head until that side of the body hits the ground. That contact starts the next cartwheel.

A simple way to picture it, offered by Popular Science, is twirling a rope in a circle while holding one end in your hand. Here, the hand is the head. The rope's loop sweeps around, but the point where it is held does not travel in a circle. That comparison is an analogy rather than a result from the paper, and like any analogy it simplifies, but it captures the central idea: the rotation is real, and it happens around the head, not with it.

Defector's account adds a detail on contact: by whipping its body through the air, the snake alternates between hitting the ground with its back and with its belly. This also explains something that looks odd in the video. The animal does not behave like a single hoop. Different regions of the body play different roles, and the roles hand off to each other from one cycle to the next.

The quiet head

The most striking finding concerns the front end. While the rear part of the body goes through large rotations, the head stays aligned with the direction of travel. It does not tumble over with the rest. Its height above the ground also stays comparatively constant, especially when the snake is rolling fast, when the animals tend to hold the head elevated and cut down vertical head movement.

The researchers interpret this as a form of control. According to the authors' press release, the combination of rapid body rotation and head stabilisation may help the snakes maintain control during high-speed rolling. Without any structural separation like the axle of a wheel, the snake functionally divides its body into regions that undergo large rotational movements and a region, the head, that remains stabilised.

There is a useful comparison in the paper itself. As the study's authors write, a similar example of head stabilisation occurs in flying snakes, which keep a relatively constant head orientation during take-off despite large body movements. “Despite their distinct locomotor contexts,” they add, “the similarity between these systems suggests that stabilizing the head, and the locomotor control it facilitates, may be important for dynamic locomotion.” Flying snakes of Southeast Asia launch from trees and glide for a few seconds to another. Birds are often held up as the masters of a steady head atop a moving body, Imbler notes, and dwarf reed snakes have now shown they can manage something similar.

Why does it matter that the head stays put? Because the head carries the sensory organs the animal uses to find its way. The authors argue that a steady head helps the snake stay in control, and the race results are consistent with that: the snakes followed a track only 20 centimetres wide, a little narrower than a sheet of printer paper, despite the speed. The press release stresses that this is not simply uncontrolled tumbling. They also tended, in the footage, to end their run by diving under nearby objects. To the authors, that suggests the animals stay aware of their surroundings while they roll.

What the speed means

The numbers in the study are modest-sounding until you convert them. Peak forward velocities while rolling ranged from 1.72 to 3.69 metres per second. Across the sample, the average peak speed in rolling was four times that of normal lateral undulation, the familiar side-to-side slithering that most snakes use, according to Kojima. At the upper end, 3.69 metres per second is 12.1 feet per second, or about 8.3 miles per hour. At the lower end of the range, 1.72 metres per second is about 3.8 miles per hour.

Four times is the average of the peaks, and the range is wide, so some individuals and some runs were much slower than the headline. It is also worth being careful about what was measured. The animals were nudged on a purpose-built track in a laboratory, not chased by a bird or a larger snake. The paper reports kinematics, meaning how the body moves, not how often the trick saves a life in the forest. The report in The Times, as summarised by the site Journal Arta, makes the same point: the source describes the narrow-track test but does not report how the behaviour performs in a natural predator encounter.

The 2023 estimate that a 25-centimetre snake covers six body lengths in five seconds is a different kind of number, since it comes from a single animal filmed in the field. It fits the same broad picture all the same: a small animal that, for a few seconds, is far faster than its normal pace suggests.

Why roll at all?

Speed is the obvious benefit. A snake that is four times faster than its normal crawl has a better chance of reaching cover, and the authors of the 2026 paper note that the snakes often ended a run by diving under objects. Surprise may add to it. Researchers have speculated that the display could startle or confuse a predator, and the 2023 authors also suggested a scent argument, since a rolling snake touches the ground only in patches and so leaves a patchy trail. They pointed out that king cobras use scent cues to track prey, so a broken trail could make it harder for such a predator to hunt a dwarf reed snake. That is a hypothesis; the new paper does not test it.

Then there is the cost. Rolling probably burns a lot of energy. Kojima told Imbler: “This mode of locomotion may require a lot of energy, but we don't yet know how long the snakes can sustain it.” The 2023 authors had said they believed it could not be sustained over long distances. The two teams agree on the direction of the answer, but nobody has yet measured the cost. That is why a snake that can roll does not roll all the time: it is, as far as anyone can tell, a last resort.

What nobody knows yet

The new study answers the question of how, and leaves a large one hanging: why these snakes. The ordinary reed snakes in the experiment could not or would not do it, and the difference raises possibilities that the researchers cannot yet distinguish.

Jessica Tingle, a biologist at Brown University who was not involved in the study, told Science News, as reported by Smithsonian Magazine, that many questions remain, including how the snakes evolved such a “strange and possibly demanding” movement. She asked whether dwarf reed snakes have “something special in their anatomy, physiology or neural control that lets them do it when their close relatives apparently can't or don't”. Her second question is the more provocative one: do all snakes have the basic equipment, and just not use it? Socha leans toward the first option. He suspects there is something particular about the dwarf reed snake that allows it to move this way, but, he said, exactly what is going on in its body and how the snake does it is still an open question.

The behaviour is also not confined to the three species in the experiments. Another member of the genus, Pseudorabdion albonuchalis, has been reported to cartwheel too. A 2025 note in the Herpetological Bulletin by Oldřich Kopecký asked whether cartwheeling is a common defence in dwarf reed snakes and linked to video evidence of that species doing it, although not under laboratory conditions. Quah said in 2023 that no other snake species had been formally recorded cartwheeling but that it could be more widespread among relatives of the dwarf reed snake. The 2026 data now cover three of the species and one genus that does not roll, which is a good start for mapping where the trait sits on the family tree.

What a small snake teaches

The paper's broader claim is about how bodies and behaviour relate. In Kojima's words: “Behavioral innovation can give rise to surprising new abilities that we would not expect from an animal's appearance alone.” Nothing in the shape of a dwarf reed snake advertises that it can do this. It has no legs, no spines, no flexible shell, no wheel-like structure. What it has is a long, flexible body, and the control to organise that body into regions with different jobs: one that rotates powerfully and one that stays steady. The press release from the authors makes the same point in plain terms, that physical structure does not set the full range of movements an animal can perform.

There is also a modest lesson about how much is still undiscovered in places we think we know. The behaviour was described in field guides and passed on as anecdote for years before anyone measured it. It took a roadside chance encounter in 2019, a research trip to Borneo, a racetrack narrower than a sheet of printer paper, and many hours of watching slowed-down video before the details emerged. Socha put it this way: snakes are experts at doing things out of our sight, and even in places with many snakes you mostly do not see them. His prediction, he said, was only that this would not be the last surprise.

For now, what we know is limited and clear. Thirteen out of thirteen dwarf reed snakes tested could roll; six out of six larger reed snakes could not. The rolling reaches speeds about four times the best a snake normally manages on the ground. And in the middle of the spin, the head holds still. As Kojima's team found, one small animal in the leaf litter of Borneo has found a way to build a wheel without an axle, and to steer it. We have an earlier article on this research for a quick summary: Tiny Reedsnakes Roll Four Times Faster Than They Slither. More stories like it are collected in our science section.

Sources

• Kojima Y., Fukuyama I., Hossman M. Y., Kaliang C. H., Nishikawa K. “Locomotor kinematics and head stabilization in rolling snakes.” Current Biology 36(20), R1061–R1063 (2026): doi:10.1016/j.cub.2026.08.057
• Quah E. S. H., Grismer L. L., Anuar M. S. S. “Observations and description of a rare escape mechanism in a snake: Cartwheeling in Pseudorabdion longiceps.” Biotropica 55(3), 568–572 (2023): doi:10.1111/btp.13213
• Toho University press release on the study, via ScienceDaily: These tiny snakes roll four times faster than they slither
• Natural History Museum: Snake that cartwheels away from predators described for the first time
• Live Science: Watch bizarre snake ‘cartwheel’ away from danger at more than 12 feet per second
• Smithsonian Magazine: These snakes can cartwheel away from danger
• Defector: Rolling snakes reinvent the wheel
• IFLScience: Rolling snakes can clock up speeds of almost 4 meters per second
• Popular Science: This snake cartwheels to escape danger
• Kopecký O. Herpetological Bulletin 172 (2025): doi:10.33256/hb172.3940