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How boa constrictors breathe to kill

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A snake winding around a stick.

These snakes can grow up to 4 metres long, and squeeze their prey to death
Image: ©iStock.com/jbmake

Instead of biting with poison, boa constrictors wrap themselves around their prey and squeeze them to death. But if a boa constrictor’s squeeze can kill, how does the snake survive the pressure without suffocating themselves?

Snakes are long and skinny compared to most animals. And on the inside, their organs are relatively long and skinny too!

Most animals have 2 lungs. We humans have one on each side of our chests. But snakes have one main long lung. Their second lung is either small or absent depending on the species, and it isn’t used for very much at all!

How does breathing work?

Diagram of snake anatomy.

A snake’s organs are elongated to fit in their long, thin bodies
Image: Wikimedia Commons/Uwe Gille, David Shaw Remix CC-BY 2.5

When humans breathe, a muscle under our lungs, called the diaphragm, pulls down. This makes our lungs bigger, and air is sucked in through the nose and mouth to fill them. Snakes breathe a bit differently – they make their lung bigger by expanding their ribs instead.

Recently, scientists from Australia and the United States took a closer look at how boa constrictors breathe. They squeezed small sections of these snakes while taking videos and scans, including X-rays. That way, they could see how the snakes’ ribs moved as they breathed.

So what happens when a boa constrictor gets squeezed? The snake will expand their lung using only some of their ribs. If a part is getting squeezed, they breathe with ribs higher up or further down instead. And when scientists measured nerve signals, they discovered the squeezed bits of snake weren’t even trying to breathe!

Surviving the squeeze

Boa constrictors have some helpful tricks when it comes to breathing under pressure. When they’re constricting their prey to death, they probably aren’t using their entire body to squeeze. And the bits that aren’t squeezing can be used to breathe instead.

But this research helps explain how snakes survive other squishes too. Snakes are famous for swallowing their prey whole, even when the meal weighs more than the predator! A big dinner will squeeze a snake hard from the inside. But snakes don’t suffocate on their snacks – they just breathe around them!

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3 comments

  1. Now I want to be a snake, I feel like being able to breathe with different parts of my lungs would be really useful.

      Reply
  2. As an asthmatic person who uses a number of breathing techniques to cope, I have absolute respect for this manoeuvre

      Reply
  3. How do they do that?! Snakes are the coolest!!!!!!!!!!!!!!!!!!!!!!!!!!!!:)

      Reply

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