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Salamander Tongue Is World's Most Explosive Muscle

Scott Norris
for National Geographic News
March 9, 2007
 
The greatest burst of power from any animal muscle comes from the tongue of a tropical salamander, scientists have announced.

The giant palm salamander of Central America (Bolitoglossa dofleini) captures fast-moving bugs with an explosive tongue thrust that releases over 18,000 watts of power per kilogram of muscle.

That shatters the previous record of 9,600 watts per kilogram, held by the Colorado River toad.

Stephen Deban of the University of South Florida in Tampa said the secret to the tiny salamander's strength lies in its "ballistic" tongue-firing mechanism.

His team used high-speed video and implanted electrodes to study the prey-catching behavior of several related salamander species.

Much like an arrow shot from a bow, Deban said, the giant palm salamander's bony tongue is launched with an initial burst of energy and flies forward under its own momentum.

The "bow" is provided by elastic fibers in the salamander's mouth that stretch to store muscular energy and then release it all at once.

"You can pull the string back as slowly as you like, but when you let it go, the arrow achieves a much higher rate of energy release," Deban said.

The team's findings appeared in the February 15 issue of the Journal of Experimental Biology.

Built for Speed

The salamander's ballistic firing permits the tongue's sticky-padded tip to reach prey in just a few thousandths of a second, Deban's team said.

Such speed is critical for overcoming the countermeasures evolved by some insects.

Crickets and cockroaches have sensors capable of detecting tiny air currents generated by an incoming tongue. Those sensors are linked directly to muscles used in escape, Deban explained.

But salamanders aren't the only creatures that add a "spring-loaded" charge to their raw muscle power.

Similar mechanisms have been found in the legs of turkeys and frogs and in the tongues of chameleons.

(Read a related story about chameleon tongues and other "evolutionary oddities.")

Deban noted that the greatest power output from muscle acting alone has been measured in quail as they flap their wings in vertical takeoff.

"The salamander muscle produces 16 times the peak instantaneous power output of the quail, albeit by using the trick of elastic storage," Deban said, referring to the mechanism that fires the salamander's muscular "bow."

Kiisa Nishikawa, of Northern Arizona University in Flagstaff, has studied ballistic prey capture in toads.

She noted that the giant palm salamander's record-setting power is partly a matter of its size—despite its name, the salamander is only a few inches long—since smaller animals tend to be proportionally stronger.

"A toad with the same body mass as Bolitoglossa would have a similarly high power output," she said.

Nishikawa said that an added feature of the salamander's quick tongue is the lizard's habit of sitting tight until an insect wanders by, rather than chasing after prey and risking the attention of larger predators.

Study leader Deban agreed.

"They are slow-moving animals in every way except with regard to their tongues," he said.

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