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Scientists (Finally) Discover How Dogs Use Their Tongues to Drink

"The motions are precise, even mathematical," says one researcher. Just the same, it ain't pretty.

Michael Leaverton  |  May 29th 2013

Here’s a question you’ve probably never had the good sense to ask yourself: What is the mechanism by which a dog drinks? In other words: How does a dog’s tongue work?

Throughout history, this riddle has been left largely unanswered, because dogs drink so damn fast. Then someone invented the high-speed video camera, and civilization cleaved into pre-HSVC and post-HSVC worlds. One of the neat things we could do in this post-HSVC world was watch crocodiles take down wildebeest crossing a river in super-slow mo (so cool). The other thing we could do was figure out how a dog’s tongue works, according to NPR.

Behold: A dog’s tongue becomes a ladle! An inverted ladle, to be precise.

“It dips down, scoops up some water, using its tongue as a pulley,” writes Robert Krulwich. “This was a revelation.”

However! Once scientists put down the high-speed video camera and took up their measurement tools, they discovered that all the water that the dog had scooped up with this tongue-as-ladle fell out when the dog actually brought the damn thing to his mouth.


In short, the dog is basically a toddler eating soup for the first time. So, why aren’t all dogs dead of thirst? Scientists entered a conclave and promised not to emerge till they had the answer. Eventually, they had the answer. The world waited.

The dog’s tongue is a sticky wick! OF COURSE THAT MAKES PERFEC — huh? A dog’s tongue is a sticky wick? That’s what we’re paying you for? What does that mean? Let’s hand this off to Krulwich:

“A dog will extend — no, that’s too polite a word — the dog will thrust its tongue into the water and then whip it back up, very, very fast. A stream of water attaches to and follows the tongue upward (adhesion and cohesion) — but only for a fraction of a second. Then gravity kicks in. The rising stream of water loses its upward momentum, and just as it’s about to fall back into the bowl, at exactly the point where gravity is about to win, the dog snaps its mouth shut and swallows. Done. The motions are precise, even mathematical.”

Don’t argue. It’s math. It’s physics.

(As for cats, they drink the same way, only “more carefully, more elegantly, more efficiently.” Harumph.)