The Outrageous Way That Turtles Breathe in Ice-Covered Waters

Fagjun | Published 2017-12-07 14:11

Turtles breathe through their butts to ensure that they’ll live through the winter in frozen ponds.


How do turtles survive when freshwater bodies are frozen over?

 

 

How do freshwater turtles breathe when their habitats have frozen over? It’s probably not a question that we’ve wondered about a lot--or at all--but it is somewhat interesting to think about. When the winter months come and the temperatures drop, lakes and ponds in certain areas of the world freeze over. How, then, would an animal like a turtle survive in freezing waters that have a layer of ice covering them?

 

Like other animals that need to live through a cold winter, turtles hibernate. Because a turtle is an ectotherm, its body temperature merely mimics the temperature of its environment. If waters are, let’s say, three degrees Celsius, the turtle’s body temperature will be the same. Thus, when the turtle’s body temperature drops, it goes into hibernation in the water. However, one question remains: how do turtles breathe when there’s a layer of ice covering the water?



Surviving the Winter


Painted turtles are one particular turtle species that can survive on little oxygen. [Photo by Greg Schechter]

 

 

Most turtles will not be able to survive freezing temperatures, and they will not be able to survive having ice in their bodies. Thus, when winter comes, the turtles will not be hanging around out of the water. Water functions like some sort of a temperature buffer, shielding turtles from the worst of the cold. If the turtles stay in the water, even though they’re under a layer of ice, their body temperatures will not go lower than freezing.

 

Obviously, when a pond is covered in ice, a turtle will not be able to swim to the surface in order to breathe in oxygen. Very little oxygen will also be able to get into the water, and it’s not just that--there are other organisms in the water that also need to breathe. Thus, there can only be so much oxygen for turtles.

 

Fortunately, hibernating turtles actually don’t need much oxygen. As a turtle’s body temperature drops, so does its metabolism. When that happens, the turtle begins to need less and less oxygen. Snapping and painted turtles in particular have the amazing ability to recalibrate their metabolisms in such a way that they won’t need much oxygen. The problem with this is that if the turtles go for too long with this kind of metabolism, acids may build up in their tissue. Lab tests have shown that turtles can live in this state for up to 100 days.



Cloacal Respiration


When spring comes along, turtles emerge to finally bask in the sun.

 

 

While the turtles remain underwater for the duration of their winter hibernation, they breathe by using a process called cloacal respiration. That’s the technical term for “butt-breathing”. Birds and reptiles have a multi-purpose part of their body called a cloaca, which enables urination, defecation, reproduction, and egg-laying. Turtles add another use to this body part: respiration. Water, which contains oxygen, enters the cloaca. Then, the blood vessels in the cloaca absorb the oxygen. Et voilà, respiration.

 

Turtles are deeply interesting and amazing creatures. They live long lives, and they’ve been around for hundreds of millions of years. The fact that freshwater turtles breathe through their butts in the winter is basically just icing on the cake.

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