How have snakes evolved to move so effectively without legs?
How do so many snakes climb trees or swim?
Snakes are interesting creatures from nose to tip, but their bodies are so different than ours.
It makes you wonder:
How do snakes move?
A snake moves by controlling its muscles and scales in patterns and sequences. There are four main patterns of snake movement which use specific muscle groups and the scales on their bellies. Snakes use different types of movement for different environments and purposes.
The Four Main Ways Snakes Move
Snake movements require detailed small muscle and scale control.
When moving, different parts of a snake’s body are at rest or moving at any one time.
Different types of movement are used to navigate different types of surfaces.
One general truth in all these movements is a snake’s scales resist moving sideways or backward.
Therefore, most of a snake’s movement is forward.
Serpentine Or Lateral Undulation
Most snakes move using lateral undulation.
In this movement, a snake pushes against objects in its environment by forming S-shaped curves with its body.
It forms these curves by activating its large dorsal muscles in sequence.
Each following muscle then follows the curves already made by the head and the rest of the body.
Usually, the surrounding environment provides enough resistance to make forward progress possible using this method.
Caterpillar Or Rectilinear
Larger snakes like vipers, boas, and pythons primarily use this method to move in straight lines over the ground.
Unlike lateral undulation, the body curves here are formed up and down rather than side to side.
The belly scales of the snake alternately stick and come off of the ground using static friction, while the muscles which connect the skin to bone control these scales and overall motion.
You will generally see sidewinding movement in snakes which live mainly in mud and sand.
For certain desert snake species, sidewinding means as little of their surface area as possible touches hot sand at once.
Sidewinding involves snakes launching themselves forward from their heads and moving the rest of their bodies sideways.
Sidewinders travel diagonally rather than strictly forward, leaving distinctive, j-shaped tracks with their movement.
When a snake needs to climb a vertical surface or move in a tight space, they use their belly scales to grip the surface and bunch their body into tight curves.
After bunching, they will straighten out their body to move forward, repeating the movement repeatedly to climb a vertical surface.
This movement involves simultaneous one-sided activation of the muscles along the body.
A surprising number of snakes regularly climb trees or posts.
For example, juvenile boa constrictors spend most of their lives in trees, coming down and staying on the ground when they have reached adulthood.
Rat snakes have often been observed climbing posts into birdhouses to raid nests in suburban North America.
While these four main methods of movement are the most common among snakes, some species have adapted to unique environments or situations which require different forms of movement.
A snake’s methods of movement mean all snakes are capable of swimming to some degree.
Whether or not a snake needs to swim depends on its environment.
A desert pit viper may go its whole life without encountering a large body of water, while an anaconda, which lives in the rainforest, spends much of its time in rivers.
However, those who spend much of their lives underwater have evolved several adaptations to help them swim.
Most species of sea snake spend their entire lives swimming in the ocean.
They use lateral undulation for swimming and navigating shallow waters.
Sea snakes have a tail sort of like a paddle or flipper.
They have evolved to be vertically narrow and flat, unlike most snakes, which are horizontally flat and have flat undersides.
These adaptations help them effectively swim against a large volume of water with many currents.
While they do go to the surface regularly to breathe, they also take oxygen from the surrounding water and absorb twenty-five percent of the oxygen they need through their skin.
This means they stay underwater up to two hours on a single breath.
Flying Or Gliding
There are five types of flying snake in the rainforests of South and Southeast Asia.
These snakes fly or glide from tree to tree, kind of like a flying squirrel.
Snakes like the paradise tree snake spend much of their lives in tree branches.
They will sometimes launch themselves downward to get to another tree or the ground, undulating their bodies side to side in midair to “fly.”
Observers have described their movement as swimming through the air.
They use this unique form of movement when startled.
They’re escaping over a smoother surface.
This pattern of movement is not often used and has been observed not to be very useful.
Since it is rare, the muscles and scales involved with slide-pushing have not been identified yet.
When slide-pushing, a snake will curve its body into irregular bends, pushing down on the surface to create resistance in movement.
We hope you have enjoyed learning about how snakes move.
The four main movements of snakes involve concentrated muscle and scale control and direction.
Usually, snakes move by lateral or serpentine undulation.
This applies to snakes who use it to fly or glide through trees or swim in rivers or oceans.
Larger snakes will use rectilinear or caterpillar undulation to move across the ground.
Snakes which have to move across hot sand or mud will sometimes use sidewinding, launching their bodies diagonally across deserts.
When a snake needs to climb a tree or post, it will use a concertina movement, bunching itself up, then straightening out along a vertical surface or in a tight crevice.
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