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Yesterday, I saw a snake smoothly glide over about 30 feet of rough gravel in our parking area to get to the woods. It showed no sign of discomfort -- but I am not sure I would know what an uncomfortable snake looked like.

I suppose part of the answer is that the area of the snake's underside that is in contact with the ground is large enough so that the pressure is low; but that gravel is very pointy.

Question: Is the skin on a snake's underside tougher than on its topside?

(It was about 18 inches long, thin, a pretty brown with yellow spots.)

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    The snake probably only weighs a pound or two at most. – whatsisname Mar 13 '16 at 6:17
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    I wonder if this question might be better at biology.stackexchange.com – James Jenkins Mar 13 '16 at 21:40
  • @James Jenkins Please, please I do NOT want to participate in any more SEs. If you really think this is inappropriate, vote to close. – ab2 Mar 13 '16 at 21:42
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    ab2 - I don't think it's inappropriate, or even off topic here, but it is certainly much more on topic at Biology. – Rory Alsop Mar 14 '16 at 10:46
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The skin of snakes is covered with tough scales, similar to fingernails. On the upper surfaces of their bodies these tend to be approximately round or diamond shaped and on the underside are usually longer bands running across.

These scales both provide protection from abrasion and can also help it to grip surfaces it is moving over.

On some species the texture of the scales is very obvious eg the horned viper

In general both top and bottom sides of a snake are well protected by scales but the bottom scales tend to be smoother and specifically adapted to give it traction for movement.

This image of a cobra gives a good view of the belly scales and this one of a python

6

There is a good answer already. But I have some deeper thoughts:

Snakes are possibilities. They are diversified, and classified over a huge range. Just as per their physical parameters, there are other aspects to differentiate.. like habits, habitat, and another aspect that catches lesser thoughts is Locomotion.

We all know some snakes move fast (although a very relative term with no reference), some don't.

If I ask a person how did it go? He/She would most likely reply bluntly that "It glided!"

Barring the locomotion of aquatic snakes (Hydrophiinae) and sticking strictly to the terrestrial locomotion, we can say that they have different locomotion types. Usually the type of locomotion depends on the species and what is it doing.


Side winding

Very common. Almost every other snake we snake, does a Side-winding locomotion. Do not compare extremities by getting confused with the term Side-Winder. Have you seen a snake moving in mud or sand which disables a snake push against an irregular surface, like stones, sticks, etc? In side-winding, head and tail are the supports for the snakes movement to push against. Its body is lifted off the ground to move sideways. It keeps on head and tail into the same cross direction of its body. Observing carefully, you'll see that parts of its body positioned in one direction are never lifted off the ground, while the other segments are lifted up, resulting in a equidistant pattern drawn on the sand/mud. So, its almost half the friction of its body against the surface, lesser work.


Concertina

These are also plenty around. Have you seen a snake climbing a tree or moving on a slippery surface? In this method the snake winds up itself and then it uses the energy to thrust forward. Then the front part of the body stays on the surface and the back part of the body is pulled up to be coiled again. To notice, this method is a lot of friction with the surface, using a lot of its energy. So, do these snake move fast? No, but can they strike fast, Yes.


Serpentine

Have you seen a Rat snake move, or a Cobra? In this method there is movement that is from side to side. Head is lifted up, move its upper body to 10 o'clock, pull the body, oh, gotta go 2 o'clock, move its upper body that way, and repeat, the poor tail is just dragged on straight.


Rectilinear

Have you seen a large viper move? Or a Boa, or a Python. Thats rectilinear movement. Just straight drag of the whole body. Its usually in large snakes. They just move straight.


To answer the real question: Is the skin on a snake's underside tougher than on its topside? I think the whole answer above makes it pretty clear its less about the scales and its toughness, but more about how the snake moves. Yet to literally answer the questions, I am really bumped up, can't really tell if there is one theory that can be applied to all the snakes. The underside scales (Subcaudal, Ventral and less significantly the paraventral scales) are more flexible, agile than the upperside scales, thats for sure.

Good reads:

  • 1
    Next level answer. TY +1 – Citizen Jun 3 '16 at 6:38

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