Inhale, Exhale

Look: Scientists finally discover how boa constrictors can eat giant meals without suffocating

Henrik Sorensen/DigitalVision/Getty Images

Henrik Sorensen/DigitalVision/Getty Images

The boa constrictor may be non-venomous, but the 10-foot-long snake is known for its lethality in other ways.

Boas are known to wrap their thick bodies around animals and squeeze them to death.

Then, they swallow their prey whole — fur, skin, bones, and all — and let their digestive systems do the work.

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Mark Lui

But their ability to devour carcasses whole puts extreme strain on the snakes’ ability to breathe.

Their stomachs press against their lungs, making it difficult to expand their ribcages and suck in air after a big meal.

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Researchers set out to answer the question of how boa constrictors can kill and eat without suffocating in a study published Thursday the Journal of Experimental Biology.

“When you kill something really big [and eat it], you fill yourself up in this immense way. You’re completely full to the gills, literally.”

John Capano, organismal biologist and study co-author, tells Inverse.

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For the study, the researchers recruited several boa constrictors and took X-rays of their bodies under different conditions.

Mark Lui

The snakes were fitted with a blood pressure cuff around a section of their bodies to mimic the squeeze of a big meal or the act of constriction.

When one part of the boa’s rib cage is restricted (right), it can still use another part to continue breathing (left).

John Capano

Even when the boa’s rib movement is restricted while resting on a table, it can expand and contract its lungs in the suspended areas.

Scott Boback and John Capano

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The researchers learned that the snakes are able to alternate which part of the ribs they expand to breathe during different activities, an act known as modular ventilation.

This diagram shows the different parts of the ribs that the boa will expand when doing different activities.

Scott Boback

This ability was likely an important part of the snake’s evolution, helping it adapt to hunt down large prey and be able to digest it without cutting off airflow.

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Combined with constriction and extremely flexible jaws, modular ventilation adds to the adaptations that make the boa a fearsome predator.

Capano says it’s unclear when these traits evolved, but likely that they developed in tandem, building off of each other.

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“I think that [these traits] all kind of evolved in concert. They were all probably extant in some form, and then just kind of kept growing over time.”

Capano tells Inverse.

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Read more about this study here.

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