It sounds like a joke. It is not. Some turtles really can extract oxygen from water through their cloaca — the same multi-purpose opening used for excretion and reproduction. The technique is called cloacal respiration, and it has been studied in detail since the 1970s.
But here is the part most articles get wrong: not all turtles can do it, and the ones that can do not rely on it the way fish rely on gills. This guide covers what cloacal respiration actually is, how it works, which species can do it, and what it means for the turtle in your tank.
What Cloacal Respiration Actually Is
The cloaca is a single opening at the base of a turtle's tail that serves three functions: excretion of waste, reproduction, and — in some species — respiration. It is the "multi-purpose exit" that most keepers know from anatomy diagrams.
Cloacal respiration is the process by which dissolved oxygen in the surrounding water diffuses through the cloacal lining into the turtle's bloodstream. It is not the same as breathing air with lungs. It is closer to the way a fish's gills extract oxygen from water — but happening in the rear end rather than the head.
The technique is sometimes called "anal respiration" or "rectal respiration" in older literature, but "cloacal respiration" is the correct scientific term.
How It Works: Bursae and Papillae
The mechanism depends on two structures inside the cloaca:
Cloacal bursae. These are two sac-like diverticula that branch off the cloaca. They are highly vascularized — meaning they have a rich blood supply — and can expand and contract to pump water in and out.
Papillae. The inner lining of the bursae is covered in tiny, finger-like projections called papillae. Each papilla contains a dense network of capillaries. The papillae increase the surface area of the bursae dramatically, which increases the amount of oxygen that can be absorbed.
When the turtle is submerged, it periodically pumps water in and out of the bursae. Oxygen in the water diffuses across the thin walls of the papillae into the bloodstream. Carbon dioxide diffuses the other way, out into the water.
This process is passive — the turtle does not need to actively "breathe" through the cloaca the way it breathes with its lungs. It just needs to keep water moving through the bursae.
Which Turtles Can Do It
Cloacal respiration is not a general turtle ability. It is documented in only a handful of species, most of them highly aquatic.
| Species | Cloacal Respiration? | Notes |
|---|---|---|
| Fitzroy River turtle (Rheodytes leukops) | Yes, primary | The best-studied example. Can remain submerged for weeks. |
| Florida softshell (Apalone ferox) | Yes, supplementary | Uses bursae to extend dive times, especially during winter. |
| Other softshells | Yes, limited | Many have well-developed bursae but rely mostly on lungs. |
| Red-eared slider | No | Must surface for air. Can hold breath 30–60 minutes when active. |
| Painted turtle | Marginal | Absorbs some oxygen through skin during winter brumation, but not primarily through the cloaca. |
| Musk turtle | No | Must surface to breathe, though it can stay submerged for hours when resting. |
| Snapping turtle | No | Highly aquatic but still needs to surface to breathe. |
| Sea turtles | No | Hold breath for hours, but rely on lungs and blood oxygen storage. |
The Fitzroy River turtle is the extreme case. It lives in fast-flowing rivers in Queensland, Australia, where the water is highly oxygenated. It can remain submerged for weeks at a time by relying almost entirely on cloacal respiration, surfacing only occasionally to top up its lungs.
Why It Matters for Survival
Cloacal respiration gives turtles two important advantages:
1. Extended dive times. A turtle that can absorb oxygen from water does not need to surface as often. This reduces exposure to predators, especially birds of prey and crocodilians, and allows the turtle to remain in deep water where food is more abundant.
2. Winter survival. During brumation (the reptile equivalent of hibernation), many turtles spend months at the bottom of a pond or river. Cloacal respiration — along with oxygen absorption through the skin — allows them to survive without surfacing through ice.
Without these adaptations, temperate turtles would not be able to overwinter underwater, which is essential for their survival in frozen lakes and rivers.
What About Your Pet Turtle?
The turtle in your tank almost certainly cannot breathe through its cloaca. Red-eared sliders, painted turtles, musk turtles, cooters, and Chinese pond turtles all have lungs and must surface to breathe air.
This has practical implications for tank setup:
- Water depth is fine, but the turtle must be able to reach the surface easily. Deep water is not a problem for strong swimmers, but hatchlings can tire and drown if the water is too deep and the climb to the surface is too far.
- Do not rely on "they can breathe underwater." They cannot. A turtle trapped under a tank decoration or wedged behind a filter can drown.
- Resting underwater does not mean breathing underwater. A sleeping turtle can stay submerged for a long time by slowing its metabolism, but it will still surface to breathe every so often.
- Water quality matters more than you think. Because turtles surface to breathe, they spend less time underwater than fish. But they still need clean water for skin, shell, and eye health.
Other Turtle Breathing Adaptations
Cloacal respiration is only one of several adaptations turtles use to survive in water. Others include:
- Skin respiration. Many aquatic turtles can absorb some oxygen through the skin, especially in areas with thin, highly vascularized tissue like the cloaca, throat, and limbs.
- Blood oxygen storage. Turtles have a high tolerance for lactic acid buildup and can store large amounts of oxygen in their blood and tissues. This allows them to hold their breath far longer than mammals of similar size.
- Metabolic depression. During brumation, metabolic rate drops dramatically — sometimes to less than 10% of normal — which reduces oxygen demand.
- Buccal pumping. Some turtles pump water in and out of their mouths to increase oxygen extraction from the water around their throat.
Together, these adaptations make turtles one of the most breath-hold-capable vertebrate groups. Even species that cannot breathe through their cloaca can survive long dives that would kill a mammal.
Frequently Asked Questions
Can turtles really breathe through their butts?
Some species can — but not all, and not the way most people imagine. The technique is called cloacal respiration, and it allows certain aquatic turtles to absorb dissolved oxygen from water through the cloaca. The Fitzroy River turtle of Australia is the best-studied example. Most common pet turtles, including red-eared sliders and painted turtles, cannot do this.
How does cloacal respiration actually work?
The cloaca has two diverticula called cloacal bursae, which are lined with small, finger-like projections called papillae. These papillae are packed with blood vessels. When the turtle is submerged, it pumps water in and out of the bursae, and oxygen diffuses directly from the water into the bloodstream. This allows the turtle to stay submerged for weeks at a time without surfacing for air.
Which turtles can breathe through their cloaca?
The ability is rare and well-documented in only a few species. The Fitzroy River turtle (Rheodytes leukops) of Australia is the most famous. Some softshell turtles, particularly the Florida softshell, also have well-developed cloacal bursae and use them to supplement lung breathing during long dives. Common pet turtles like red-eared sliders, painted turtles, and musk turtles do not have this ability.
How long can a turtle stay underwater without breathing air?
It varies enormously by species. Red-eared sliders can stay submerged for 30 to 60 minutes during normal activity and up to several hours when resting or hibernating. Painted turtles can survive underwater for months during winter brumation, absorbing oxygen through the skin and cloaca. The Fitzroy River turtle can remain submerged for weeks thanks to cloacal respiration.
Do pet turtles need to come up for air?
Yes. Most common pet turtles — red-eared sliders, painted turtles, musk turtles, cooters, and Chinese pond turtles — must surface to breathe air. They have lungs and cannot extract enough oxygen from water to survive indefinitely submerged. If you see a pet turtle staying underwater for extended periods, it is usually resting or sleeping, but it will still surface regularly to breathe.
Final Thoughts
Cloacal respiration is one of the strangest and most fascinating adaptations in the animal kingdom. It shows how far evolution will go to solve a simple problem: how to stay underwater longer.
For pet turtle keepers, the practical takeaway is simple. Your turtle almost certainly cannot breathe through its cloaca. It needs to surface regularly for air. Provide a tank where the turtle can easily reach the surface, a basking platform where it can dry off, and clean water. That is what it actually needs.
For more on turtle anatomy, see our vocal cords guide and our tank setup guide.
Sources & References
- Priest, T. E., & Franklin, C. E. (2002). Effect of water temperature on the cloacal respiration of the Fitzroy River turtle. Journal of Experimental Biology, 205(8), 1037–1046.
- King, P., & Heatwole, H. (1994). Partitioning of aquatic oxygen uptake among different respiratory surfaces in a freely diving pleurodiran turtle, Emydura macquarii. Copeia, 1994(1), 151–160.
- Ernst, C. H., & Lovich, J. E. (2009). Turtles of the United States and Canada (2nd ed.). Johns Hopkins University Press.
- Bonin, F., Devaux, B., & Dupré, A. (2006). Turtles of the World. Johns Hopkins University Press.
- Jackson, D. C. (2000). Living without oxygen: lessons from the freshwater turtle. Comparative Biochemistry and Physiology Part A, 125(3), 299–315.
