Just saw a post on the popular page, “Snake moving in a straight line freak me out’. It made me realize that I have no idea how snakes move. How do snakes move when they don’t have any legs or other limbs?
In: Biology
It’s similar to how worms move, if you watch a worm move you can see it’s skin stretching forward and the rest of the body following. Snakes do this on a smaller scale using their belly scales that can move semi independently.
The straight movement is all belly scales (like mlucaswalker said). On different surfaces they also add techniques. They take advantage of little bumps in the uneven ground to push off — this is where the common serpentine moves comes from. There also snakes that do a sidewinder move to cross slippery sand — kind of speedy throw your head out and snap your body along sideways.
The wide, overlapping scales on their cute lil snake tums. They allow the snake to get traction wherever they’re crawling, and they use diagonal motion (slithering) to scoot along. Fittingly, the scales are referred to as ‘scutes’.
The scales on a snakes belly have a preferential grip on the ground. They function like a ratchet. Now, different snakes have different means of locomotion, but they all work basically the same way. They lift part of their body off of the surface and move it forward while the part of the body in touch with the ground tends to stay in place due to this ratchetting effect.
There are basically four or five types of snake locomotion. The one you are seeing in that image is rectilinear motion. In this situation the snake scruntches up the skin on the bottom of its body and scootches itself forward. The scales on the bottom of the snake slide forward easily but don’t slide backwards easily, so it’s able to slide up bits of it’s stomach and then push them backwards, moving forward. This is a technique commonly used by heavy bodied snakes and also on smooth surfaces.
The next kind of snake movement is lateral undulation, your classic back and forth slithering . The snake moves its body side to side, forming wave that move backwards from head to tail. These waves push against things (or even the ground, thanks to those scales) and as they move backwards along the body of the snake, the snake goes forwards. [Video](https://www.youtube.com/watch?v=e-TmYs1Eq8E)
Then you have sidewinding. Sidewinding snakes pick up their head, move it ahead and plant it on the ground, then sort of throw their body forward and to the side in a loop, then repeat. Only two parts of their body are on the ground at the same time, and they move forward by pushing back with those parts. This kind of movement is fast and efficient and works particularly well compared to other ways of moving on open, loose surfaces. (https://www.youtube.com/watch?v=pbj3BlZGxcg)
You also have concertina movement. In concertina movement the snake basically anchors the back end of the body, extends the front end, anchors it, and pulls up the back end. Then it anchors the back end and repeats. This is slow and inefficient but is useful for moving in tunnels (where the snake braces against the walls) or reaching from branch to branch in trees.
(https://www.youtube.com/watch?v=a9y-C7LDpq0)
[Here’s](https://academic.oup.com/icb/article/60/1/156/5818495) a scientific paper on the topic, with pictures.
Held a snake before, they’re VERY strong, and have a great sense of their surroundings. You can feel them slithering on your hand and gripping tight with their tail, I’d assume it has to also do with their muscles let alone their flexible skin and scales.
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