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Snake Anatomy–What’s Underneath The Scales?

Snake Anatomy–What’s Underneath The Scales?

Have you ever wondered how a snake is able to swallow such large prey? Maybe you want to know how they squirm, writhe, and fit into tiny places. Do they have bones at all, or are they made of something else?

Believe it or not, snakes do have bones, quite a lot actually. They have hearts, lungs, brains, and most other organs you’d expect. To fit them into an elongated shape though, these organs have to be placed strategically and don’t look like what you might think. 

Sit back and get ready as we go over the snake anatomy, and find out what’s hiding underneath the scales.

About Snake Scales

Scales of a python up close
Scales of a python up close.

When a snake eats a meal its body stretches to accommodate its size. The scales don’t stretch though, because they are unable, but the skin underneath unfolds in order to let the snake expand.

When a snake grows, it sheds a layer of skin and scales. Depending on how much it grows and other factors, a snake can shed once or multiple times per year. When they shed, even the eye covering is shed.

Before a snake sheds, the eye can look cloudy and slightly blue. During this time the snake’s vision is impaired and it will either try to hide somewhere or become rather aggressive. If you ever see a snake in the wild with clouded eyes, leave it alone, even mild-mannered snakes can get very grouchy when they can’t see.

The underside or belly of a snake is covered in large, bands of scales called scutes. These are what help the snake move. By alternatively stretching and contracting the scutes, snakes are able to “slide” on the ground.

While this seems like a cumbersome way to move, keep in mind that the fastest snake that moves this way can slither on the ground at 12 miles per hour. That record belongs to the extremely venomous black mamba.

If 12 mph doesn’t sound very speedy, let’s take a look at human running speed. The average, non-athlete human runs at an average speed of 8 miles an hour. That’s a lot faster than I can run.

Athletic sprinters can outrun the black mamba because their average sprint speed is around 18 mph, but for average Joes like you and me, we’d be in trouble.

That’s not even the fastest snake in the world. The sidewinder holds that title because it can travel up to 18 miles per hour. When it’s traveling across the hot desert sand, it has to move fast or end up getting toasted in the heat.

Now let’s find out what’s underneath the scales:

What’s Inside A Snake’s Head?

A snake head up close
A snake head up close

Let’s start from the front of the snake and work our way down. First off we have the snake head. Inside you’ll find a skull, brain, nostrils, mouth, tongue, and even teeth.

Makings Of The Snake’s Skull

Unlike our skull which only has one movable joint—the jaw—snakes have several movable parts in their skull. Most of their bones are connected to stretchy ligaments. This is an adaptation that allows the snake to swallow prey much bigger than they are.

A snake can move either side of its jaw independently of the other side. Speaking of the jaw, they don’t actually “unhinge” their jaw. I know, we’ve all heard that, and have been taught that myth, but it’s actually untrue.

A snake’s jaw stays connected to the upper cranium. It just has a special bone structure and long, stretchy ligaments that allow for the huge gaping maw to open and swallow very large prey.

Speaking of the jaw, did you know that all snakes have teeth? Not all snakes have fangs though, those are reserved for the venom-producing snakes. Snakes have teeth to help hold onto prey, and aid in swallowing.

Some snakes like the Burmese python have very large, pointed teeth, while others can have tiny, almost invisible teeth. They are pointed backward and very sharp so that when prey struggles, they can’t get away.

If you’re ever bitten by a snake, if you try to pull away (yes, that’s a natural instinct that’s very hard to overcome), the teeth only dig in deeper. You should shove forward to dislodge the teeth, then when the snake opens its mouth, you can remove your finger, hand, or whatever was bitten.

Snakes Have Brains

Surrounded by bone and situated in the cranium, just behind the eyes, is a small snake brain.

It’s very small, and most snakes only operate on instinct. For instance, some snakes that are born conjoined with two heads rarely make it because the two heads compete for resources.

When a two-headed snake catches prey, the head will often fight over the food. Even though it’s going to the same place. It’s also been observed that these two heads will try to eat each other if they are hungry or smell the other.

These are the reasons two-headed snakes rarely live very long.

Snake Sensory Organs

Snakes can see, hear, and smell with organs inside their heads. Some snakes have heat-sensing pits, and all snakes have a hearing bone called an ossicle, but they lack a tympanic membrane (eardrum), and middle ear.

Their eyes are covered by a clear, immovable lens. When a snake sheds its skin, the lens is shed as well.

While snakes can hear, it’s thought that they only sense low-frequency vibrations. Especially vibrations that come from the ground around them.

With special organs called the Jacobson’s organ and their specialized tongue, snakes are able to smell very well. When snakes stick their tongues out and flick them up and down, they are sending minuscule particles into their nostrils.

From there, the air and scent particles enter into the Jacobson’s organ and they can detect danger or prey. This sense is so acute they can detect how far away it is and in which direction.

One sense snakes do not have is the sense of taste. Though they do have a small, pointy, and forked tongue, snakes have no taste buds.

Can you imagine not ever being able to taste anything? No pizza, no ice cream, and you’d never taste the salty, meaty, smoky goodness of bacon! I don’t know how I’d survive.

Snake Muscle Structure

A snake body curved with muscles
A snake body curved with muscles.

Snakes have a lot of muscles underneath their scales. The average snake has between 10,000 and 15,000 muscles! The average human only has about 700 to 800 muscles.

These muscles help the snake to move, constrict, climb trees, and swallow its food. It’s one of the reasons even smaller snakes are incredibly strong for their size. They are mostly muscle!

Snake Bones

An x-ray of a curled up snake
An x-ray of a curled-up snake.

Snakes do have many bones in their body. The average number of bones in a snake is around 300 to 400. Though larger, longer snakes can have many more. Long pythons or anacondas can have upwards of 1800 bones!

Most of a snake’s bones come from vertebrae and ribs. The longer the snake, the more of these bones.

The reason a snake is able to stretch out so wide when they swallow large prey is that these ribs are not fused together like ours are. Snakes have no sternum, and the ribs remain very flexible. The ribs can flare out to accommodate wide meals.

The reason snakes can bend into tiny shapes or even ball themselves up is because of the design of the vertebrae and how they are connected. Unlike most mammals, whose spines are only able to bend so far, snakes have much more mobility.

A snake’s vertebral column has many articulating, or moveable facets that give them greater maneuverability and better mobility.

Snakes Are Separated Into Quadrants

A long snake body slithering through sand
A long snake body slithering through sand.

Since snakes don’t have limbs or other outwardly distinguishable parts, they are separated into 4 equal sections called quadrants when speaking of their anatomy. Many of their organs are elongated and some are located in different areas depending on snake species.

Snake Anatomy–Quadrant One

The first section includes the head, which we already went over, the trachea, esophagus, glands, and the heart.

Snakes have nostrils they breathe through, and a glottis they use to breathe through their mouth. When a snake swallows a large item, the glottis moves to the side so it can still breathe.

In quadrant one, a snake has several glands. These include the parathyroid, thymus, and thyroid gland. In addition to these glands, the heart is also located in this quadrant.

Depending on the snake species, the heart can be located in the second quadrant.

Snake Anatomy–Quadrant Two

Continuing on into the second quadrant, we have a continuation of the esophagus that leads into the stomach. In snakes, the stomach is elongated and usually pointed at both ends.

A snake’s stomach is able to expand quite a bit in order to fit large prey animals. It is also very acidic when food is introduced. The snake’s digestive system can go dormant or become active depending on when the snake eats.

When the digestive system activates, the pH in the stomach can quickly go from 7 which is neutral, to 2 which is acidic enough to dissolve bones.

While the stomach takes up a lot of space in a snake’s body, it isn’t the biggest organ in this area, that award goes to the liver.

The lungs are also present in quadrant two. This organ is different depending on species, or rather the number of lungs.

Some snakes only have one lung, some have two lungs, and still, others have three lungs!

Snake Anatomy–Quadrant Three

In this section of the snake, we have the remainder of the elongated stomach, which connects to the small intestine, and part of the lungs. The gallbladder, spleen, pancreas, adrenal glands, and gonads make up the rest of quadrant three.

Snakes like boa constrictors and pythons have a separate spleen and pancreas, whereas other species of snakes have a combined organ. This fusion of the spleen and pancreas is called the splenopancreas. 

Snake Anatomy–Quadrant Four

In the final section of the snake, you will find the small intestine connects to the large intestine. Kidneys, the cloaca, and for male snakes, the hemipenes are located in quadrant four.

Snakes don’t have a bladder, so they don’t store urine. Instead, the kidneys filter the blood and drop urinary waste through the ureters and directly into the cloaca.

Reptiles and birds have a cloaca, which is a chamber that serves several functions in one. Both fecal and urinary waste is excreted through the cloaca, and it’s where females lay eggs, and mating occurs.

Snakes also have musk glands located in the cloacal vent. While adults usually don’t use these glands often, juveniles are more liberal with smearing musk on predators. It smells horrible and is very difficult to remove.

Fun fact; I had snake musk smeared on me when I caught a garter snake one time. I wanted to relocate it because I didn’t want it to get harmed by big machinery or certain people who think all snakes shouldn’t live.

When I picked it up, it wrapped around my arm and proceeded to deposit a large dose of feces and urine. As an added thank you, before I could unwrap its tail, it smeared a small dose of musk on my arm.

It took several cleanings and a lot of perfume to eradicate the smell. I don’t recommend it.

How Do Some Snakes Swallow Other Snakes?

Snake in its enclosure among small wood chips
Snake in its enclosure among small wood chips.

If you know much about snakes, you know some are cannibalistic. King snakes, and the longest, venomous snake in the world, the king cobra, feed on other snakes.

If a snake’s stomach only comprises a section in quadrant two and part of quadrant three, how can it swallow something as long, or longer than they are?

While the esophagus and stomach can expand to accommodate large meals, they can’t stretch longer than the snake itself. Instead, snake-eating snakes compress their long meals.

As an experiment, get a piece of yarn, rope, or string and stretch a length out. Now take your length of material and “zig-zag” it. This way the yarn shortens in length.

Snakes who eat other snakes do this to compress their meal so the tail isn’t left sticking out of their mouths. Part of the undigested snake will remain in the esophagus until room is made in the stomach as it’s broken down.


Do snakes have hearts?

A: All snakes have hearts that pump blood throughout their bodies just like ours. A snake’s heart is shaped differently though. A snake’s heart is divided into three chambers instead of four like a human heart. They have two atrial chambers and a single ventricle that is incompletely divided.

Can a snake survive being cut in half?

A: A snake cannot survive being cut in half, and it will not regenerate. Both halves of the snake would perish. Even if a latter section of the fourth quadrant was cut off from the snake, it would not survive. Because of the elongated organs, the only part of a snake that can be cut off that would not destroy the snake is a small section of the tail.

Anywhere else the snake is cut, vital organs are being severed which leads to the end of the snake’s life.

Do Snakes Have Teeth?

A: All snakes have teeth. Smaller snakes may have teeth too small to see and too fine to cut through human skin. Not all snakes have fangs though. 

A snake’s teeth are dropped throughout its life and replaced, much like sharks’ teeth.

Do Snakes Have A Brain?

A: Almost all animals have a brain, snakes included, though it’s not a very developed brain. Some creatures that don’t have a brain include several sea creatures such as clams, sea cucumbers, jellyfish, sea urchins, and sea sponges.

That’s All Folks!

There we have it, all the parts of a snake’s anatomy. Snakes have many of the same organs as we do, only they are shaped differently to make up for their long thin body. 

We hope you have found this article on snakes informative, and you now know a little bit more about these misunderstood animals. 

We love to hear from our readers, so if you have any comments, stories, or something you’d like to add, drop us a line below! See you on the next one! 

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