Supernatural spit is the frog's secret weapon for catching bugs

February 2, 2017, 8:03 a.m.
A bullfrog tries to capture an insect
Photo: Martin Hejzlar/Shutterstock

Frogs are famous for the long sticky tongue they use to snag prey. But what is it about this tongue that allows a frog to nab an insect, pull the insect back to its mouth with lightening speed, and eat it — yet the stickiness doesn't glue the frog's mouth shut?

The secret is super sticky saliva that's reversible. A new study from the Georgia Institute of Technology demonstrates that the saliva can turn from a honey-like viscosity to one more like water and back again, and all within a few seconds.

Lead author on the study Alexis Noel explains: “There are actually three phases. When the tongue first hits the insect, the saliva is almost like water and fills all the bug’s crevices. Then, when the tongue snaps back, the saliva changes and becomes more viscous — thicker than honey, actually — gripping the insect for the ride back. The saliva turns watery again when the insect is sheared off inside the mouth.”

Meanwhile, the sticky spit needs a way to get over to an insect to snag it. Here's how that works:

"The tongue, which was found to be as soft as brain tissue and 10 times softer than a human's tongue, stretches and stores energy much like a spring," Eurekalert explains. "This combination of spit and softness is so effective that it provides the tongue 50 times greater work of adhesion than synthetic polymer materials such as sticky-hand toys."

Super-special spit and a trippy tongue make capturing insects a snap.