This is scientific American 60 second science. I'm Christopher in Tagayata.

You might think frogs catch insects because their tongues are sticky.

But why is the tongue sticky? And how does it actually adhere to these insects at these very high accelerations?

Those are the questions Alexis Noel, a PhD candidate in mechanical engineering at Georgia Tech,

wanted to answer.

So she and her team got frog

tunks from a dissection lab, as one does, and tested their consistency, 10

times softer than human tongues, a texture more like brain tissue.

Their tongue is very much like a sponge.

It actually is infused with this very thick, very viscous saliva.

That saliva was their next study subject.

And in order to test the saliva, we had to get about a fifth of a teaspoon of fluid,

which is a lot of saliva in a frog's case.

They put the saliva in a rheometer, a tool that can measure viscosity, and they found that frog

saliva is what's called a shear-thining fluid.

It's viscosity changes depending on conditions.

You might be more familiar with a different shear thinning fluid.

Ketchup. When you smack the bottom of the ketchup bottle, you're actually invoking

sheer forces within the ketchup itself. And the ketchup, because it's sheer thinning, its viscosity actually drops and allows it to slide out of the bottle easily.

So back to our frogs. The tongue shoots out, hits the bug, and deforms around it.

That impacts like a smack on a ketchup bottle. It changes the saliva from thick and sticky to more watery, free to flow all over the bug.

Then the tongue bounces back like a bungee cord and the saliva thickens up again.

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