Business Insider Edition

Watch: Turtles can breathe with their butt underwater thanks to their shell - here's how

Uma Sharma , Business Insider US
 Aug 11, 2019, 04:57 PM
  • A turtle can't crawl out of its shell, just like we can't crawl out of our own skeletons.
  • In fact, the shell is actually part of a turtle's skeleton, comprised of the ribcage, vertebrae, and sternum.
  • But if you could peer inside a turtle shell, you'd find some of the most unusual features in the animal kingdom.
  • For one, they’re some of the only animals that can breathe with their butts.
  • For more stories, go to 

A turtle's shell is as much a part of its body as our rib cage is of ours. In fact, it is their rib cage, and their spine, and their vertebrae, and their sternum. Basically, a turtle's skeleton is inside out. And just like you can't take a skeleton out of a person, right, you can't take a turtle out of its shell either.

Business Insider spoke with Maria Wojakowski, a biologist who's been studying turtle ecology for more than a decade, to explain how it’s anatomy works including how it can breath through its butt. 

A turtle’s hips and shoulders are inside the turtle's rib cage. Turtles are one of the only land animals on the planet with this feature.

They're also some of the only animals that can breathe with their butts.

Inside a turtle shell is a very particular respiratory system. Most land animals breathe by expanding and contracting their ribs, which creates a natural pump that guides air in and out of their lungs. But turtles can't do this because their rigid shells don't expand. So instead they rely on sheets of muscles within their shell to pump in oxygen through their mouths, most of the time.

Then there are other times when turtles breathe out the other end, more specifically, through what scientists call the cloaca. It's the same opening that turtles use to urinate, defecate, and lay eggs. And in some cases, it can double as a set of gills, sucking in water and absorbing the oxygen within. Scientists think that turtles do this when they're spending long periods of time underwater, like when they're hibernating.

And if you look closely at the inside of a shell, you'd discover another feature that helps with hibernating underwater: a scaffold-like structure that can store and release chemicals. That structure helps turtles breathe without any oxygen at all.

Watch also: Indian temple helps nurture 'extinct' turtle back to life

Many turtles hibernate in frozen ponds that are starved of oxygen, and to survive, their metabolism switches over from aerobic to anaerobic. That means they stop using oxygen for energy and start using glucose instead via a process called anaerobic respiration. And the byproduct of that is lactic acid. Now, theoretically, this acid could build up in a turtle's body and kill it.

That's where the shell's structure comes in. It can absorb the lactic acid as well as release a bicarbonate to neutralize that acid. It's essentially Tums, but for turtles.

So, as it turns out, having a shell is pretty handy for certain situations. In fact, scientists think that turtles originally got their shells for digging, likely more than 200 million years ago.

Receive a single WhatsApp every morning with all our latest news: click here.

Also from Business Insider South Africa:

  • Indicators
  • JSE Indexes

Get the best of our site delivered to your inbox every day.

Sign Up