Have you ever wondered how turtles spend so much time underwater? Do they have superpowered lungs? Do they have some kind of hidden gill system?
While they don’t have superpowers, they do have a super-powered tail end. Reptiles, some fish, amphibians, and birds have an all-purpose anus called a cloaca. This funnily-named bum is an opening that empties the body of urine and feces, and is used for mating and laying eggs.
A few select species of turtle can also breathe through their cloaca. Well, breathing might be an exaggerated term; the correct term is cloacal respiration.
Turtles can only get a fraction of the oxygen through cloacal respiration that they can get through their lungs and regular breathing. Turtles “breathe” through their butts when they are going through periods of very limited activity such as hibernation.
Keep reading to find out more about this fascinating trait.
Turtles are unique because of their shell. Did you know that turtles and tortoises are fused to their shells? A turtle’s shell is as much a part of its body, as our skin is a part of ours. They can even feel through their shell.
The shell acts as the armor for the turtle but is made up of two parts that are fused together. The top part of the shell is called the carapace, while the bottom part is called the plastron.
The outer layer of the shell is made up of keratin. This is the same material that makes up the hair and nails of humans.
A turtle’s ribs are also fused to its carapace and are a part of the shell. Because of this, turtles are not able to expand their lungs as we can. Instead, they have to expand out the front and back of their shells.
Other than having to breathe through an immovable shell, turtles still breathe much the same way we do.
Turtles breathe air through their nostrils (external nares). From there the air passes through the glottis and into the trachea, into the bronchi, and then onward to the lungs.
Cloacal Respiration Isn’t Very Effective
Many adult turtles can hold their breath for an average of 45 minutes, but if they are being active, they will have to surface for a fresh breath of air more often. Most times you’ll probably see your pet turtle surface every few minutes for a breath.
Why do they come up for air if they could just stay submerged and breathe through their cloacas? That’s because cloacal respiration isn’t an effective process, and the longer they stay submerged using this process of respiration, the more dangerous it becomes for them.
Some aquatic turtles have small sacs called cloacal bursae in their vents. These are tissue sacs filled with blood vessels that circulate the water so they can absorb some oxygen from the water while getting rid of carbon dioxide.
Other species that don’t have bursal sacs have folds and ridges in their cloacas. This extra surface area does the same as bursal sacs, by allowing an exchange of gasses.
The high concentration of blood vessels located in the cloaca allows turtles (such as painted turtles and Japanese pond turtles) to absorb oxygen from the water.
Turtles can receive some oxygen this way, but it’s only about one-quarter of what they can receive when they come to the surface for lungfuls of air.
One turtle that can get nearly 70% of its oxygen needs through cloacal respiration is the Australian White-Throated snapping turtle, (Source University of Queensland Australia). Also called the “Bum-breathing turtle,” this snapper is critically endangered.
Water Doesn’t Have Much Oxygen
Another reason breathing through the anus isn’t very effective is that water contains very little oxygen. Sure fish can “breathe” underwater, but that’s because gills have evolved especially for underwater life.
Water is much denser than air and so contains nearly 200 times less oxygen than the same amount of atmospheric air. When a turtle is active underwater—searching for food, swimming away from predators—cloacal respiration can’t keep up with the body’s need for oxygen.
Cloacal Respiration Helps Protect Turtles From Predators
Sometimes it’s hard work to get from the bottom of the river or lake to the surface for a breath of air. Fast-flowing bodies of water can make a turtle work harder for a breath of air. So cloacal respiration can allow them to stay underwater longer and save some precious energy.
For ambush predators like the snapping turtle, cloacal respiration helps them stay down, motionless for a longer period. This can be the difference between getting a big, meaty fish, or going hungry.
Being able to stay submerged longer also helps to keep turtles away from predators. Larger turtles don’t have much to fear while underwater, except for alligators and crocodiles, but babies and smaller turtles often have many more predators.
While turtles are hiding in the muddy or sandy bottoms of rivers and lakes, they are protected from predators. When small turtles have to swim to the surface for air, they can become targets for large fish, other turtles, crocodiles and alligators, and even birds.
The less they have to surface for air, the fewer times they have to become exposed to potential predators.
When Do Turtles Breathe Through Their Butts?
Turtles use “butt breathing” while undergoing long periods of little to no activity, such as hibernation. Using this method as well as buccal pumping, and cutaneous respiration, turtles can sometimes stay submerged for months at a time.
Buccal pumping is the process of circulating water through their mouths. Most often this process is used to smell underwater, but in periods of limited movement, they can also absorb oxygen through the vascular lining of their throats.
Some turtles such as the musk turtle use buccal pumping to absorb oxygen into blood vessels located in the throat rather than in the cloaca.
Cutaneous respiration is the same way frogs and other amphibians can derive oxygen through their skin. Some turtles, the Softshell turtle, in particular, can use cutaneous respiration.
When temperatures drop, food becomes scarce, and the turtles start to get too cold to move, they will end up hibernating in the water. Ponds will often freeze over, meaning even if the turtle wanted to breathe air, it wouldn’t be able to.
This is when cloacal respiration is extremely beneficial for the turtle. While they are in a state of suspended animation, they can get enough oxygen through other means of respiration.
As they enter hibernation or brumation as it’s called for reptiles, turtles’ heart rates also slow down, and they use significantly less energy. Since activity and metabolism have slowed so much, they can use cloacal respiration to survive underwater for extended periods.
Turtles may be air-breathing reptiles but they can respire enough oxygen through their cloacal bursae to survive through months of brumation underwater.
Turtles are ectotherms, meaning they are cold-blooded. When the temperature of their environment changes, so does their internal temperature. When the water temperature drops from 70 degrees Fahrenheit to 40 degrees Fahrenheit, so does the turtle’s body.
When turtles start getting too cool, they will come out of the water and find a warm, sunny rock or log to bask upon. That’s why you’ll often see several turtles crowded together upon a single log, they are trying to warm themselves up.
A turtle’s metabolism is also affected by the weather. When temperatures start to drop, the turtle’s metabolism slows, and alternatively, it’s hot outside their metabolism increases. During this time the turtle is much more active, it needs more food and more oxygen.
Through extended periods of brumation, the oxygen in the water can start to diminish. Maybe the turtle isn’t getting enough oxygen through cloacal respiration to keep vital functions going.
At this stage, turtles such as painted turtles and snapping turtles can survive using anaerobic respiration & metabolism, as well as active chemical buffering processes.
Anaerobic respiration can lead to a dangerous buildup of lactic acid. To combat this buildup, some turtles such as the painted turtle mobilize calcium from their bodies to neutralize the acid.
When turtles start to accumulate a lot of lactic acid in their bloodstream they begin to use up stores of calcium and magnesium carbonate from their shells. This helps to buffer the lactic acid and helps the turtles survive long, cold periods of brumation (Source American Physiological Society).
If you have a turtle that goes through the brumation process, it’s important to feed it foods high in calcium when they’re active once again. This is so they can replenish their lost stores for the next time and help re-strengthen their shell.
How Long Can Turtles Go Without Breathing Air?
In North America, six turtle species are able to carry out cloacal respiration. While this process helps them survive during brumation and during times of very limited activity, it’s not something turtles do all the time.
Some aquatic turtles can get some oxygen through buccal pumping, and through cutaneous respiration, but none of these processes are as efficient as breathing air through their lungs. Turtles still need to come to the surface on occasion and breathe air.
How long a turtle can stay submerged depends on several factors. How old the turtle is, the species, how active they are, and the temperature of the water can determine how long a turtle can stay underwater.
For the most part, turtles typically come to the surface for a breath of air every 5 to 10 minutes. This is during a normal active routine.
Smaller, or younger turtles will have to come up more often, while some sea turtles have been known to dive for upwards of 10 hours at a time.
Healthy adult turtles can easily stay underwater for around 30 to 45 minutes before coming up for a breath. This amount of time is usually seen when they are either resting, hiding, or waiting for a meal to swim by.
During brumation, especially when the water the turtle is inhabiting freezes, turtles can remain submerged for months at a time. Sometimes up to six months longer if the cold season is especially long.
Can Turtles Drown?
We know that turtles can respire underwater and even go months without breathing, but can turtles drown? Yes, they can. Regardless of all the adaptations that allow turtles to stay underwater longer than almost all other reptiles, they can still drown under certain conditions.
Even with cloacal respiration, cutaneous respiration, and buccal pumping, turtles are not able to extract enough oxygen from all of these methods together to prevent drowning. These methods usually only sustain their life and oxygen needs when the turtles are inactive.
When turtles are active, the water is warm, and they are using a lot of energy, turtles have to come to the surface for air. While they are resting at the bottom of the water, sleeping, or going through brumation, turtles can stay submerged for much longer.
When a turtle is excited or active, it will need to surface for air frequently. Turtles that get trapped by fishing nets, or other means will stress out, panic, and go through their oxygen stores very quickly and can drown.
Pet turtles can drown also. They can get stuck in filters, especially if they are small and the water flow is powerful. They can get trapped in plants, or if they get flipped onto their backs in shallow water, a turtle can drown.
If you have a pet turtle at home, look for possible hazards. If you have a strong pump or filter and a small turtle, you may need to get a flow reducer.
Make sure any holes or drains aren’t big enough for your turtle to get a foot stuck, and you don’t have long, “rope-like” plants or accessories that could entangle your turtle.
If your turtle gets trapped, it will panic and get stressed out. This excited state will cause the turtle to burn through its breath of air and the stored oxygen quickly, leading to a tragic drowning.
If you’ve ever wondered how turtles can stay underwater for so long, and how they can hibernate (brumate) underwater, it’s because of cloacal respiration. This method of breathing through their butts isn’t very effective when they are active though.
Cloacal respiration is an effective way to get oxygen from the water while they remain inactive during the cold winter. Combined with buccal pumping, and cutaneous respiration, turtles can stay submerged for months at a time.
The oxygen supplied to the turtle with these types of respirations is minimal. Surviving on such limited oxygen supplies requires a slow metabolism which is achieved because of the drop in temperature during winter.
If the oxygen diffused in the pond or other body of water runs low, the turtle can always rely on anaerobic respiration. Anaerobic respiration refers to breathing without oxygen, which is something turtles can do for a short while.
Unfortunately, anaerobic respiration creates a dangerous buildup of lactic acid, making extended anaerobic respiration unsustainable. With the ability to extract minerals stored in their shells, they can mitigate some of the lactic acids, allowing turtles to survive harsh winters.
If you’re a reptile enthusiast and are interested in similar topics about turtles and their lifestyle, habitat, eating, and sleeping habits, we have several informative articles on our website. Feel free to check them out and leave us a comment below!