A new study in has revealed for the first time how horned frogs are able to catch, lift and eat enormous preys weighing almost 400-lb, with their tongue.
An article published in Christian Science Monitor (CSM) based on research conducted by Thomas Kleinteich and Stanislav N. Gorb, of the Christian-Albrechts-Universität-Kiel in Germany, says that the tongues of certain horned frogs can adhere to an object with enough force to pull prey three times its own weight. Every predator uses hands, jaws or beaks to catch its prey but frogs use something much stranger: their tongue.
An experiment was designed to analyze how frogs snatch their prey. Just before meal times, four frogs were taken in a terrarium behind pressure sensitive glass set up and were shown a cricket situated behind the glass slide attached to a force sensor. The frogs were filmed flicking out their tongues to seize the prey, while the sensor measured the force as the tongue hit the slide. Afterwards, the researchers studied the tongue prints left on the slides and measured the contact area.
The first and strongest pulling forces averaged about 1.45 times the body weight of the frogs, and the duration of this adhesive phase was much longer compared to the impact phase. They found that certain frogs can lift meals up to three times heavier than their body weight using a sticking mechanism of their tongue similar to the tacky glue on Post-It notes. The study was published Thursday in the journal Scientific Reports.
Thomas Kleinteich, lead author of the study and a zoologist said, “I knew these frogs could eat large things, but I didn’t really expect that the forces would be that high.” “What we actually found was that the tongue adhesive forces were well beyond the body weight of these frogs,” he said. “And, another thing which we found, which I did not expect, was that the mucus or the slime on top of their tongues does not seem to be that important as people always assumed.”
Research on sticky gecko feet has already yielded new technologies. Recently, a US Military tech development program produced paddles for soldiers to scale walls easily based on the same research. Kleinteich plans to continue the project with different species of frogs to identify the mechanism that makes frog tongues stick. “Once we know this, we can think about developing new adhesives for technical applications,” he said.