The lungs of a human are relatively large and wide. So, how can snakes fit lungs inside their body, when they’re so long and thin? This can make the breathing process of snakes a bit of a mystery.
Snakes have lungs and breathe through their nostrils. They can breathe through their mouth, but prefer not to. They also have a special organ called a glottis, which helps them breathe even when they’re eating a large meal. They don’t have gills, and can’t breathe underwater.
How a snake breathes is a fascinating process. Scientific research has been done to understand how it works, and how it is different from how humans breathe.
What Organ do Snakes Use to Breathe?
Snakes are similar to humans in many ways. Their internal structure is the same, but more stretched out. The top 1/3 of the snake is their neck, the next 1/3 is where their organs are, and the final 1/3 is tail. Regarding organs, they’re also the same.
They have stomachs, intestines, kidneys, a liver, and lungs. Some snakes have two lungs whereas others only have one, but their lungs are functionally the same as humans.
They have a ribcage that expands and contracts, to draw air in and push it out again, although they don’t have a diaphragm.
Snakes also have a glottis, which leads into their windpipe. This is what they use to breathe.
How do Snakes Breathe Without a Diaphragm?
The diaphragm is a vital muscle that enables people to breathe. The diaphragm sits just below the lungs and above the abdominal cavity.
It moves up and down as we breathe—down when we breathe in, and up when we breathe out. By moving down, it makes space for the lungs to expand into, and this draws air in like a vacuum.
But snakes don’t have one. So, how do snakes breathe without a diaphragm? Instead of lowering or raising the diaphragm, they expand the muscles around their lungs and windpipe. These muscles move the ribs outwards to give air more room to flow in.
Do Snakes Have Nostrils?
Yes, snakes have nostrils. They don’t have noses, but they do have air-holes that are analogous to the nostrils. There is one crucial difference, though.
Snakes don’t sniff with their nostrils. Instead, they use them to breathe. Instead of sniffing, they flick their tongues to pick up chemicals from the air.
The chemicals then go to a separate organ called Jacobson’s organ, which the snake uses to identify prey, predators, etc.
Snakes do breathe through their nostrils. They can also breathe through their mouth, but they prefer not to. If a snake will only breathe through its mouth, this is usually a sign of a respiratory infection.
As they breathe in, the air comes through their mouth and into the windpipe, but not before going through a special organ called the glottis.
What Is the Glottis?
The glottis is like the end of a tube that’s been closed. That’s precisely what it is. It’s the end of the windpipe, which the snake normally keeps closed. When they breathe, the glottis opens up to let air in, and it can open up to let the air out too.
But the glottis isn’t just any old organ. It’s an evolutionary advantage. Humans got the short end of the stick because we have our windpipe next to our esophagus. When we want to breathe, we open the top of the esophagus and close our windpipe (or vice versa, as required).
Snakes, though, have their glottis. When they’re eating a big meal, they can move the glottis outside of their mouth so that they can continue breathing. Snakes need to be able to do this because it can take them a long time to swallow large prey.
When the mouth is closed, the glottis connects directly with the hole that comes down from the nasal cavity. This means that air will flow directly through the nostrils, into the internal nasal cavity, through the glottis, and into the lung or lungs.
This is different from how humans breathe since our windpipe stays open to both the mouth and the nasal passages at all times while breathing. You can tell because if you try hard enough, you can breathe in through your nose and mouth at the same time.
As an interesting aside, there’s a small piece of cartilage near the end of the glottis. When the snake pushes air out of their lung or lungs, this piece of cartilage vibrates quickly. This is what creates a snake’s hiss.
Do Snakes Have Lungs or Gills?
So, some snakes can swim underwater. Sea snakes live almost their entire lives underwater. But just because they live in the sea, that doesn’t mean that they have gills.
So, how do snakes breathe in water? Well, they don’t. Think of whales. They live underwater, but since they’re mammals, they have regular lungs. That’s why they have to surface periodically to breathe. Sea snakes, and all snakes, are the same. They don’t have gills.
However, some sea snakes have developed the ability to breathe through their skin.
How do Snakes Breathe Through Their Skin?
Sea snakes can use a process called ‘cutaneous respiration’ to breathe, at least a little, through their skin. They are still air-breathing reptiles, just like all other snakes. But cutaneous respiration allows them to spend even longer underwater. Here’s how it works:
- Normally, the fact that snakes are covered in scales prevents cutaneous respiration. However, sea snakes move blood from their lungs to the capillaries in their skin while underwater.
- The blood carries waste products—carbon dioxide and water that are normally expelled through breathing—to the skin, where it is then diffused into the water around them. You can tell because their skin turns pink, because of the blood.
- At the same time, the snake can absorb oxygen from the water flowing around them. It flows across the skin and these capillaries, and the oxygen is taken up and into the blood. It can then be used by the snake so that they can stay underwater for longer.
According to a paper written by Martin E. Feder of the Committee on Evolutionary Biology (University of Chicago), sea snakes may be able to absorb 30% of their oxygen in this way.
This gives them a huge advantage, in that they stand much less chance of drowning, and won’t need to keep surfacing for air all the time.
However, this doesn’t apply to all snakes. It only applies to sea snakes. Normal snakes don’t respire through their skin and rely solely on regular breathing.
Do Snakes Have a Trachea?
The trachea, or windpipe, is what carries air to the lungs. All land animals have developed a trachea so that they can breathe.
Snakes have a long trachea that reaches down 1/3 of their body since 1/3 of their body is the neck. This trachea functions in the same way that it does in humans.
Regarding structure, the trachea is like a thin, very long pipe. The glottis is the end of the windpipe, which has evolved to be able to open and close.
The rest of the windpipe is surrounded by rings of cartilage, which give it structure. Without these rings, the trachea would collapse, and the snake would be unable to breathe.
For reasons we don’t quite understand, the rings aren’t complete circles. There is a small gap, which leaves the ring looking more like a C than an O.
The rest of the ring is covered by a thin layer of tissue that stops air escaping, but doesn’t provide the same protection that cartilage would. Why not just have a full cartilage ring? It’s unclear.
Some snakes have two small, undeveloped tracheal lungs. These are lungs that are further up the windpipe and closer to the mouth. A paper in the journal PLOS One explored the issue, and how they seem to be unused vestigial remnants from ancestral species.
What Are Snake Lungs Like?
Most snakes have only one lung. In all snakes that have one lung, it’s the right lung, and the left lung has become smaller and smaller until it’s a vestigial remnant.
The left lung ranges from about 15% of the size of the right one to not being there at all. You can find left snake lungs in less well-developed snakes like boids, but not in more highly-evolved snakes like colubrids, which have lost them completely.
And even their central lung is a little different to ours. The top of their lung—the part closest to their head—is a regular lung, just like ours.
It has small pockets that the air fills up, and then the oxygen from the air is passed into the bloodstream. When the snake breathes out, waste chemicals from the blood go into the air that they then get rid of.
How Long Can Snakes Hold Their Breath?
The lower portion of the lung is what’s different. The lower part of the lung is like a tiny air sac. It stores air that the snake might need later, just in case. This is how snakes can spend so long underwater because they have an air sac that they can use for later.
It’s like their very own natural version of a scuba diver’s air tank. In sea snakes and other snakes that swim, this second part of the lung is very long, even reaching all the way down to the cloaca, and has very thick sides. This helps the snake hold their breath for very long periods of time.
Besides all that, the lung is very elongated. This happened over many millions of years as the snake evolved to become longer and flatter.
Snake Respiratory Infections
This is where bacteria or a virus infects the mouth, throat or lungs and makes it difficult to breathe. Snake respiratory infection symptoms include:
- A runny nose
- Sneezing, as the snake is trying to clear their nose out
- Your snake may have to breathe through their mouth
- Difficulty breathing, which creates a wheezing sound
If you notice these signs, it’s a respiratory infection. RIs are usually caused by poor conditions, like if the enclosure is too cold or too humid. If you suspect that your snake has a respiratory infection, take them to a vet immediately. They’ll be able to help you return your snake to full health.
The fact that the way they breathe is ever so slightly different to how we do it makes it a fascinating subject and should help you understand your pet even better than before.