Game
Gaits
Snakes move in different ways on different ground. Pick the gait that grips, keep its rhythm, and watch the tracks it leaves.
Based on published research · pending expert review
Course 1 of 3Dry scrub
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Playing as Saw-scaled viper. Keys 1–4 choose a gait; Space drives it (in sidewinding, ← and → in turn). Esc pauses. F toggles full screen.
Choose a course
Cross grass, a tunnel, quiet ground near a mouse and loose sand. Pick the gait that grips each one, and keep its rhythm.
Lateral undulation
Tap Space on the beat. Each tap on time strengthens the wave.
Concertina
Hold Space to bunch into folds; let go when they are set to reach forward.
Rectilinear
Hold Space steadily. Letting go and pressing again is jerky and noisy.
Sidewinding
Press ← and → in turn (Space alternates for you), each as the last lift lands.
Course complete
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Section by section
The real gaits
Lateral undulationGrips best here: open grass
Waves of bending pass along the body, and every part of it slides over the ground at the same time. On solid ground the sides of the body need something to push against, such as stones and plants.1
ConcertinaGrips best here: narrow tunnel
The snake bunches part of its body into tight bends that grip, and holds them still while the rest of the body reaches forward or is pulled up behind. In a tunnel the bends push outwards against the walls; on a branch they squeeze inwards.1
RectilinearGrips best here: smooth ground near prey
The body can stay perfectly straight. Waves pass along the belly skin while the ribs stay still: patches of skin grip the ground while the patches between them are lifted and moved forward.1,4
SidewindingGrips best here: loose sand
The snake lifts parts of its body clear of the sand and sets them down further on. The parts touching the sand stay still instead of sliding, and each contact leaves a separate, straight track about as long as the snake. The tracks lie parallel, at about 33° to the direction of travel.2
The science
How snakes move
Four classic ways of moving over land, and what each one needs from the ground.
Lateral undulation
Waves that push off stones and stems
Waves of bending pass along the body, and every part of it slides over the ground at the same time. On solid ground the sides of the body need something to push against, such as stones and plants.1
In a laboratory study, young milk snakes could not slither forward on a smooth surface but moved easily on a rough one. At speed, snakes lift the most curved parts of the body a little off the ground.6
Concertina
Bunch, brace, reach
The snake bunches part of its body into tight bends that grip, and holds them still while the rest of the body reaches forward or is pulled up behind. In a tunnel the bends push outwards against the walls; on a branch they squeeze inwards.1
It is hard work: in North American racers, concertina locomotion cost more energy than lateral undulation.7
Rectilinear
A straight, quiet creep on the belly
The body can stay perfectly straight. Waves pass along the belly skin while the ribs stay still: patches of skin grip the ground while the patches between them are lifted and moved forward.1,4
In boas and a Gaboon viper, two to three waves ran along the body at once, 18–35% of the body was still at any moment, and speeds were only 0.2–6 cm a second. The researchers describe the gait as suited to stealth, such as creeping up on prey.3
It is most easily seen in heavy-bodied vipers, pythons and boas, though nearly all snakes can do it.4
Sidewinding
Lift, place, and leave the sand still
The snake lifts parts of its body clear of the sand and sets them down further on. The parts touching the sand stay still instead of sliding, and each contact leaves a separate, straight track about as long as the snake. The tracks lie parallel, at about 33° to the direction of travel.2
In sand dunes, a sidewinder's tracks are J-shaped.8
Sidewinder rattlesnakes climbed sandy slopes without slipping. Thirteen other pit vipers, which do not sidewind, used lateral undulation or concertina on sand instead, and on a 10° slope all but one of them failed to climb. Sidewinding also costs less energy than lateral undulation.2,1
A few desert vipers specialise in sidewinding, and dozens of other species have been recorded doing it now and then. In the saw-scaled viper's genus, Echis pyramidum sidewinds regularly on sand, and Echis coloratus can sidewind when frightened or on shifting ground.9,5
Ground, not speed
Legged animals change gait mostly with speed. A snake's choice depends mostly on the shape and nature of the surface under it.1
More than four
These are the four classic modes. One review argues they hide at least 11 distinct gaits, such as different kinds of concertina for tunnels and for branches.1
The snakes in the game
- Saw-scaled viper
A 2021 study of sidewinding vipers counts it among the sidewinders. Others in its genus sidewind on sand too.5
- Indian rock python
A large, heavy-bodied python. Straight-line rectilinear crawling is most easily seen in heavy snakes such as pythons.4
- Indian rat snake
The snake on the second course. Its profile does not describe its gaits; the game lets it use all four.
What the game simplifies
- Every snake in the game can use all four gaits. Real species differ: sidewinding is a speciality of a few desert vipers, though dozens of other species have been seen doing it.9
- Speeds are much faster than in life, and every snake is the same length on screen. Real rectilinear crawling moves at only 0.2–6 cm a second.3
- The skin waves run about five times faster than the body so that a share of the belly is visibly still; the measured waves ran about three times faster.3
References
- 1
Jayne, B.C. (2020). What defines different modes of snake locomotion? Integrative and Comparative Biology 60(1): 156–170. pmc.ncbi.nlm.nih.gov
- 2
Marvi, H., Gong, C., Gravish, N., Astley, H., Travers, M., Hatton, R.L., Mendelson, J.R., Choset, H., Hu, D.L. & Goldman, D.I. (2014). Sidewinding with minimal slip: snake and robot ascent of sandy slopes. Science 346: 224–229. (Open preprint.) arxiv.org
- 3
Marvi, H., Bridges, J. & Hu, D.L. (2013). Snakes mimic earthworms: propulsion using rectilinear travelling waves. Journal of the Royal Society Interface 10: 20130188. pmc.ncbi.nlm.nih.gov
- 4
Astley, H.C. (2026). Skin deep: a novel biomimetic control strategy for rectilinear locomotion in snake robots. Bioinspiration & Biomimetics 21: 044001. doi.org
- 5
Rieser, J.M., Li, T.-D., Tingle, J.L., Goldman, D.I. & Mendelson, J.R. (2021). Functional consequences of convergently evolved microscopic skin features on snake locomotion. Proceedings of the National Academy of Sciences 118(6): e2018264118. pmc.ncbi.nlm.nih.gov
- 6
Hu, D.L., Nirody, J., Scott, T. & Shelley, M.J. (2009). The mechanics of slithering locomotion. Proceedings of the National Academy of Sciences 106(25): 10081–10085. pmc.ncbi.nlm.nih.gov
- 7
Walton, M., Jayne, B.C. & Bennett, A.F. (1990). The energetic cost of limbless locomotion. Science 249: 524–527. pubmed.ncbi.nlm.nih.gov
- 8
National Park Service. Sidewinder. Death Valley National Park. nps.gov
- 9
Tingle, J.L. (2020). Facultatively sidewinding snakes and the origins of locomotor specialization. Integrative and Comparative Biology 60(1): 202–214. pubmed.ncbi.nlm.nih.gov
The motion in the game is a model built from these findings, not a recording. The facts were checked against the sources on 8 October 2026 and are waiting for review by a specialist.