It may be hard to imagine where a long, slender snake might have lungs to breathe with. Also, snakes often put themselves in situations that seem claustrophobic or otherwise difficult to breathe in, such as diving to the depths of the sea or hibernating in an underground burrow.
Most snakes have one lung that extends through its body. They can use their mouth or their nostrils to breathe. An opening in the snake’s mouth, called a glottis, can be shifted around while the snake eats so it can continue to breathe around its prey. Snakes are also good at holding their breath, and some species of water snake can perform a kind of breathing through their skin called cutaneous respiration.
Here we explore the snake’s respiratory system, taking a look at the organs and muscles a snake depends on for breathing. Then we look at the more unusual circumstances in which a snake needs to breathe, and how the snake’s biology helps it to confront these obstacles.
How Snakes Breathe
Like other vertebrates, snakes have a respiratory system. This system includes a few different organs which help a snake to breathe.
Let’s look at how these organs work and how the snake puts them to use in challenging situations – while eating, swimming, and digging underground.
Do Snakes Have Lungs?
Snakes do have lungs. Sometimes they have two lungs – one on the right, and one on the left. However, many species of snake only have one lung. All snakes have the righthand lung. This right lung is large and extends through the snake’s body, often past the middle of its torso. The length of this right lung varies between species of snake.
The right lung has small pockets inside which fill up with air as the snake inhales. Oxygen from the air then passes into the snake’s bloodstream. Waste chemicals such as carbon dioxide are expelled from the snake’s respiratory system as it exhales.
When snakes have a left lung as well, it is usually much smaller than the right lung. Snakes with a small or absent left lung have another internal structure that helps them breathe, in their trachea.
The trachea is commonly known as a “windpipe.” It looks a bit like a long straw, supported inside the snake by cartilaginous semicircles. This tracheal structure unique to snakes is sometimes called a “tracheal lung” and it operates similarly to the snakes’ lungs.
The trachea ends in front of the snake’s heart, splitting into a pair of bronchi. The bronchi are the airways that direct the air the snake breathes into its lungs.
How Do Snakes Inhale And Exhale?
Snakes do not have a diaphragm, a muscle specially designed for helping air move through its body. Instead, the snake moves air in and out of its lungs by expanding and contracting its rib cage. The muscles around its ribs are the muscles used to breathe.
Snakes can inhale and exhale through either their nostrils or their mouths. If a snake is only breathing through its mouth, that may be a sign that the snake has a respiratory infection. Usually, a snake uses both its nostrils and its mouths to get a full gulp of air.
How Often Do Snakes Breathe?
Some snakes will alter the frequency of their breaths based on environmental factors. For example, according to the Journal of Applied Physiology, garter snakes will change how often they breathe based on how much carbon dioxide is in the air around them.
If these snakes are taking in more carbon dioxide than oxygen, they will take breaths more often and more quickly in an attempt to get the vital gases they need.
If you notice a snake seems to be wheezing or gasping for breath, or taking in more shallow and obvious breaths than normal, this could be a sign of a respiratory infection. Sadly, snakes are vulnerable to these diseases.
Can Snakes Hold Their Breath?
Snakes are masters at the breathing pause, also known as apnea. This pause happens in nearly all animals between breaths. We exhale, forcing the air out of our lungs. Then we inhale, drawing air back in. Then, we pause, but usually not for long.
A snake, on the other hand, can stay in this breathing pause from anywhere between a few seconds to several minutes. If the snake is resting and relaxed, it can pause holding in a breath for a good long time. This is especially important for snakes that swim.
How Do Snakes Breathe While Eating?
While snakes can breathe through their nostrils, that is not enough for them to get the air they need while they have a full mouth of food. So, how does a snake manage to breathe while it eats?
When a snake puts its flexible jaw around a large prey animal, the result can be near complete blockage of the air pathway. After all, many species of snakes swallow prey larger than their own body, and they do not chew.
When a snake fills its mouth with food, the tracheal lung helps it to breathe. The opening to the tracheal lung, also known as a glottis, extends outward and shifts to the side of the mouth.
This effectively extends the pathway leading to the snake’s lungs. If you look into a snake’s mouth while it is eating, you will see a sort of hole or tube in the side of the mouth. That is the glottis.
The snake breathes through this stretched-out pathway until its mouth is clear of food again. Put simply, a snake is able to shift around and rearrange the organs inside its respiratory system to make sure it remains able to breathe no matter what’s in the way.
Not only does the glottis allow snakes to breathe while they eat, but it also helps create a snake’s most iconic vocalization. When a snake expels air from its lungs with a certain amount of force, a small piece of cartilage just inside of the glottis vibrates. This vibration creates the hissing sound that you hear from a snake.
Can Snakes Breathe Underwater?
Snakes that live and hunt in the water do not have gills. They cannot only derive oxygen from the water around them as a fish does. They still require oxygen from the air to breathe. These diving snakes are true prodigies of the breathing pause, able to hold their breath for a very long time.
According to Marine Biology, while a sea snake hunts, it usually will spend 5-30 minutes underwater. Some sea snakes have been clocked at keeping themselves voluntarily submerged for as long as an hour and a half or even two hours.
That doesn’t even begin to cover long how some water snakes stay below the surface while sleeping or hibernating. Exact dive time durations differ between species and can also vary based on the temperature, depth, and turbulence of the water.
When a sea snake comes up to the surface during the day, it takes several breaths in a brief moment. These breaths are known as ventilation cycles. The snake will get the oxygen it needs very quickly before going back under again. The deeper the snake dives, the more of these quick breaths it will need to take before it descends once more.
Snakes that hunt closer to the surface will come up to breathe much more frequently than snakes that hunt in deeper waters. Other factors in how long a snake will stay underwater include how active the snake is being, and how warm the water is.
A sea snake that is more actively hunting is expending more energy, and so it will need to replenish its oxygen sooner. Additionally, water snakes are observed surfacing for air more frequently in warmer waters.
Something else that helps a sea snake stay underwater for so long without getting a fresh gulp of air is a small air sac at the bottom of their right lung. In water snakes, this lung stretches all the way down a snake’s body and into its tail.
At the far end of the lung, a small air sac will retain an extra gulp of air even when the snake exhales. Snakes that dive deeper than other species have a more dense lining to this part of the lung, helping it more easily store that air for emergencies.
Cutaneous Respiration
During sleep or brumation, water snakes do not surface nearly as often. These snakes use a different method for breathing, known as cutaneous respiration. This is a process in which gases are exchanged through the snake’s skin, taking in oxygen from the water and releasing carbon dioxide into the water.
Cutaneous respiration allows some species of sea snake to survive without using their lungs for hours, days, or even months. It does not support the more active behavior of an awake and hunting snake, however. Additionally, not all sea snakes have the ability to perform cutaneous respiration at all.
How Do Snakes Breathe While Underground?
Many snakes live in underground burrows. If you have a burrowing snake, like a garter snake, you may have seen it bury itself beneath the substrate in its tank. How do these snakes manage to breathe when they have buried underground? Aren’t these snakes concerned about cave-ins?
Many snakes that live in burrows do not dig these burrows themselves. This includes rattlesnakes, who seek out cracks and caverns in stable surfaces, such as desert rock. These snakes choose a home with room to breathe in, and they do not need to fear a cave-in in their sturdy homes.
When a snake buries itself in substrate, it is not completely encasing or imprisoning itself in the earth. Snakes leave enough room as they dig around for them to move about as they need to.
They do not go too deep below the surface, instead hiding under shrubs, decaying tree stumps, or piles of leaves and grasses. Even snakes that brumate in underground burrows rarely go deeper than around a foot beneath the surface.
Additionally, there is a lot more space between particles of dirt, sand, or woodchips than you might notice by looking at it. Snakes can replenish their supply of oxygen from the air that comes down through the cracks.
