Viscoelastic Tongue Helps Frogs to Catch Prey Easily: Research

Viscoelastic Tongue Helps Frogs to Catch Prey Easily: Research

Frogs use a viscoelastic tongue and non-Newtonian saliva to catch prey, as per a new research paper from researchers at Georgia Institute of Technology has informed. The research paper has been published in Journal of The Royal Society Interface. Frogs use their whip-like tongue and it hits the prey with a strong force. The tongue is very soft and a unique reversible saliva offers the stickiness to this action, which helps frogs to trap their prey. The swift action and stickiness doesn’t give a chance to the prey to escape. Before the prey knows it, it is already in mouth of the frog. The team of researchers at Georgia Institute of Technology filmed frogs in action in a slow-motion video.

Research team lead Alexis Noel informed that there are three phases of each attack. The tongue first hits the prey and the saliva is thin at this stage. It fills all the bug’s crevices. In the second phase, the tongue pulls back fast. During this stage, the research team noticed that the saliva thickens and becomes more viscous. The research team noticed that saliva was thicker than honey during this stage. In the third stage, the saliva turns watery again. By this time, the insect is already inside the mouth and the frog is ready to finish the meal.

The research team collected frog saliva samples and analyzed them. They also checked tongue tissue to check its softness. Research team lead, Alexis Noel, a Georgia Tech mechanical engineering Ph.D. student, said, “The tongue acts like a bungee cord once it latches onto its prey. It deforms itself as it pulls back toward the mouth, continually storing the intense applied forces in its stretchy tissue and dissipating them in its internal damping.”

The research team further informed, unlike water and honey, frog saliva can change its viscosity with shear rate, much like paint. Paint spreads easily when applied, but stays firmly on the wall once the brush is removed.

David Hu, a professor in the George W. Woodruff School of Mechanical Engineering, is Noel's advisor who has also studied how mosquitos fly in the rain, how dogs shake off water and why eyelashes need to be an ideal length. He says the frog study could help engineers design reversible adhesives at high speed.

"Most adhesives that have been created are stiff, especially tape," said Hu, who is also a faculty member in the School of Biological Sciences. "Frog tongues can attach and reattach with soft, special properties that are extremely stickier than typical materials. Perhaps this technology could be used for new Band-Aids. Or it could be used to create new materials in soft manufacturing."

The Georgia Tech team worked with Mark Mandica, the leading herpetologist at the Amphibian Foundation in Atlanta. The foundation brings together top researchers in the field of amphibian biology, conservation, and applied science to address the causes of global amphibian declines. Current research estimates that 38 percent of the world's amphibian populations are in decline or already extinct.

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