- Turtles don’t technically have butts to breathe out of.
- The “butts” that turtles do have, don’t technically breathe out of it, but it’s close.
- A turtle “butt” helps to filter oxygen into the red blood cells.
- Turtles have what is known as a cloaca and use don’t a digestive system like humans do.
If there’s something that you commonly believe to be a rule of nature, chances are that there’s an animal that breaks it. Octopi have nine brains to control their eight legs and three hearts to effectively circulate out to their extremities. Star-nosed moles are effectively blind, but the bizarre tentacles protruding from their noses can actually create a sophisticated map of the world around them through touch alone.
And a jelly located in the cheeks of sharks makes them incredibly sensitive to the electric fields of other creatures. But not every bizarre animal fact is true, and the claim that turtles can breathe from their butts seems among the most preposterous. But it’s true, at least to an extent.
The process is cloacal respiration, and it makes for one of nature’s more fascinating examples of natural selection at work.
What’s a Cloaca?
Technically, turtles don’t even have butts — and the cloaca serves a similar function for their bodies, though it’s broader in its utility. As the endpoint of both the urinary and digestive tract, it evacuates all body waste. The cloaca is also a reproductive opening for females, and males of some species use it in lieu of a phallic sex organ. The concept of the cloaca can seem alien to humans, but it’s more the rule than the exception in the animal kingdom. Reptiles, birds, and amphibians all manifest cloaca instead of distinct urinary and digestive systems — as do many types of fish.
Most mammals have evolved waste systems more sophisticated than the cloaca, though there are rare exceptions like the golden mole. And while the scientific community isn’t in agreement on exactly how these separate waste systems developed, we can still see its presence in the development of human embryos and traces where it once existed in marsupials.
How Does Cloacal Respiration Work?
In the same way that the cloaca technically isn’t a butt, what turtles do with it isn’t technically breathing. Despite that, it supplies the same basic resources all animals need — oxygen. Essentially, it’s just one other way the cloaca serves as an all-purpose waste disposal system. By contracting their cloacal muscles, they can inhale water in much the same way our breathing inhales air. The water is then carried to a pair of organs known as bursae that function in a similar way to lungs — with the unique tissues extracting the oxygen from water and expelling the unwanted hydrogen. The oxygen then filters through the tissue into the bloodstream where it’s carried to the rest of the body. The scenery may seem unfamiliar, but the path is still the same.
Why Do Turtles Use Cloacal Respiration?
The simple answer is that turtles need to breathe while underwater and that the development of cloacal bursae has proven the most effective solution short of growing gills — but not all turtles are even capable of cloacal respiration. Its presence in reptiles that has it tells us a lot about their habits and about their complicated relationship with breathing. The average turtle species will spend roughly 60% of their time in the water and the rest on land, and most of them face the same dilemma as dolphins in that they need to surface to breathe. Surfacing could make them easy prey for predatory birds like gulls and herons as well as aquatic predators that prowl the surface like crocodiles and sharks.
When breathing air, a turtle’s lungs are functionally a little different from a human’s, although the fact that they wear their ribs on the outside requires them to possess special muscles for breathing. A respiration process called buccopharyngeal pumping allows turtles to filter the oxygen from water using specialized membranes built into their mouths. But turtles have an advantage over aquatic mammals like whales and dolphins simply because they’re reptiles. Without a need to regulate body temperature, oxygen is needed in much lower volumes. Sea turtles can hold their breath for up to two hours while active and three to four times that while sleeping.
In every case, cloacal respiration is a supplement rather than a replacement for more traditional respiration. Any turtle will eventually need to come up for air, but cloacal breathing can help them extend the time underwater for significant lengths of time. This is at its most useful during colder months. When rivers and lakes freeze over, many turtles will simply retreat underwater into a state of brumation — which is equivalent to the hibernation that bears, squirrels, and other mammals go through.
The colder temperatures cause the metabolism and energy needs of the turtle to plummet considerably, and that allows some species to stay underwater for months at a time relying solely or primarily on their cloaca for oxygen. But cloacal breathing doesn’t seem to have developed exclusively for this purpose. In less extreme climates and seasons, turtles can rely on this breathing method as a sort of reserve tank so they can avoid surface predators or forage in deeper waters.
What Turtles Are Capable of Cloacal Respiration?
A Cloacal Respiration isn’t as effective compared to normal aerobic respiration, and all species of turtles are capable of breathing air from their lungs. However, Cloacal Respiration is seen only in a small number of freshwater turtles that rely on this unusual breathing to overcome breathing challenges they may face while swimming in uniquely filtered ponds such as fast-flowing waters or frozen ponds.
Regardless of how it’s employed, this unique form of respiration has been useful enough to develop in a number of different species. Here are some of the more well-known ones:
- The Eastern painted turtle is one of the most successful turtle species in North America, with a habitat range that stretches from Canada‘s eastern coast all the way down to the state of Georgia. They rely on cloacal respiration to hibernate and even absorb calcium from their shell as a way to offset toxicity from the low oxygen levels in their blood.
- The white-throated snapping turtle is an Australian species that’s also one of the largest turtles in the world. This Queensland turtle is endangered, but it can stay submerged in fresh water for up to three hours at a time. It’s believed that nearly half of this turtle’s oxygen while underwater comes from its cloacal bursae.
- The Fitzroy River turtle is also found in Queensland, albeit in the much smaller habitat of the same-named river and its tributaries. These turtles spend almost all of their lives in the water, and up to 70% of their oxygen can be derived from cloacal respiration.
- Are Turtles Reptiles or Amphibians? – Are turtles a reptile or amphibian? Learn everything you need to know about turtles here!
- Types of Pond Turtles – What species of turtles live in a pond? Check out this content!
- Turtle Lifespan: How Long Do Turtles Live? – Turtles are known to live for hundreds of years, but exactly how old can they live up to? Keep reading to find out!
The photo featured at the top of this post is © Jesus Cobaleda/Shutterstock.com
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