Special spit helps frogs get a grip on insects
Let’s get this out of the way. Frogs are cool. They jump. They thrive in water. They thrive on land. Their tongues are capable of sticking to bugs. Their tongues are like glue. This is true even of insects that are heavier than they are. Now the mysteries behind those incredible tongues are being revealed. What is the secret sauce that makes frog tongues so deadly to insects? It turns out to be something simple. It's spit. That's according Ben Guarino. He was reporting for The Washington Post.
A new study reveals that frog saliva is more fascinating than previously thought. It was published in the Journal of the Royal Society Interface. Tests showed that it’s uniquely sticky. And they showed that it's physically astonishing. It can actually change physical properties.
Researchers examined frog saliva. They looked at it in combination with the frog’s soft and elastic tongue. Fluid tests of the spit showed that it’s a non-Newtonian fluid. That means that it has properties different from normal liquids.
Your average Newtonian fluid (as described by Sir Isaac Newton) has the same properties as other such fluids. They freeze at the same temperatures. They move into containers in the same ways. And they flow with the same characteristics.
But then there are the non-Newtonian fluids—liquids. These fluids seem to have a mind of their own. Ketchup is one example. Another is melted chocolate. Lava is a third. And apparently so is frog saliva. These fluids take on different properties. They take them on at different times. And they don’t behave the same way. Just think of how the face of a cliff can turn to water during the sudden movement of an earthquake.
They studied the non-Newtonian frog spit. Researchers learned that it's reversible. That's right. It can change from a glue-like substance into a very thin fluid. And then it can change back again.
But the tongue's important, too. Researchers studied frozen frog tongues. They found that they are ten times softer than the human tongue. What happens when they are combined with the non-Newtonian spit? The uniquely soft tongues have two functions.
The thin spit is still 50,000 times more viscous than human saliva. It helps the tongue hit and release from bugs. The tongue deforms. Its contact area becomes bigger. This happens when it hits a bug. The force of this impact against the bug turns the spit into a thin liquid. This allows it to ooze around its prey. But then the tongue retracts. The saliva thickens. It sticks to the bug. This makes it easier to get the critter into its mouth.
What’s the point of studying frog spit? Why did they press on frog tongues? And why did they videotape eating frogs? Researchers talked to Guarino. They said the research could one day inspire new, resealable adhesives. The future could very well contain Post-its or envelopes with frog spit-inspired glues. There may be devices that capitalize on the frogs’ unique ability to grab bugs. For now the amazement of the little amphibians make it well worth trying to figure out what makes their tongues tick.