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The sticky, slimy tongues of chameleons and salamanders may not sound like a great inspiration for engineering projects or medical innovations. But according to researchers at the University of South Florida, the same biological mechanics used to capture and devour bugs could accomplish similar feats inside your bloodstream—and even in outer space.
Chameleons and salamanders don’t encounter one another in the wild. Chameleons prefer to stick to warmer climates amid branchy trees and bushes, while salamanders mostly keep to moist, shaded environments such as decaying leaf debris and dark caves. But being total ecological strangers doesn’t mean they have nothing in common. All you need to do is watch them eat to see the striking similarity.
“They evolved the same architecture in their bodies to fire their tongues at high speed,” University of South Florida biologist Yu Zeng said in a statement. “What’s surprising is that they achieve this using the same ordinary tissues, tendons, and bone that other vertebrates have.”
For years, Zeng has focused on ways to adapt the mechanics of insect flight to technology. More recently, however, he became interested in the animals that use their tongues to hunt them. Zeng partnered with USF animal physiology expert Stephen Deban on an interdisciplinary project aimed at better understanding the unique tongues of these specialized reptiles and amphibians.
The resulting study, published on September 8 in the journal Current Biology analyzes over a decade’s worth of video documentation of salamander and chameleon tongue utilization. Zeng and Deban’s work is the first side-by-side comparison between the two species, and shows that the animals remarkably share a “unifying mechanical model.”
What they found is that both a chameleon and salamander use this “ballistic tongue” like a slingshot. After spotting their prey and taking aim, the animals squeeze musculature inside their mouths to propel a tapered skeletal rod inside their tongues. Each species is capable of projecting their tongues as fast as 16 feet per second.
“This design decouples muscle action from skeletal movement,” the authors explained in their study, adding that the 30-fold range in body size represents “some of the most efficient energy transfer in vertebrate movements.”
The researchers believe this shared biological mechanism can provide a scalable blueprint using soft or flexible materials across a range of applications.
“Nature has already solved these problems, now we’re learning how to adapt those solutions for us,” said Deban.
Deban and Zeng say they are already having discussions with engineers about biomedical applications, including tiny devices armed with artificial ballistic tongues that clear blood clots. The same underlying principles could theoretically work for retrieving inaccessible targets in a disaster zone, or possibly even snatching the ever-growing blanket of space junk orbiting above Earth.
“It is gratifying to have a unifying story about these amazing tongues, as well as potential engineering applications after so many years of focusing on the biology of these animals,” said Deban.
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