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5 December 2013 11:26 am ,
Vol. 342 ,
Researchers have been hot on the trail of the elusive Denisovans, a type of ancient human known only by their DNA and...
Thousands of scientists in the Russian Academy of Sciences (RAS) are about to lose their jobs as a result of the...
Dyslexia, a learning disability that hinders reading, hasn't been associated with deficits in vision, hearing, or...
Exotic, elusive, and dangerous, snakes have fascinated humankind for millennia. They can be hard to find, yet their...
Researchers have sequenced and analyzed the first two snake genomes, which represent two evolutionary extremes. The...
Snake venoms are remarkably complex mixtures that can stun or kill prey within minutes. But more and more researchers...
At age 30, Dutch biologist Freek Vonk has built up a respectable career as a snake scientist. But in his home country,...
Since arriving on the island of Guam in the 1940s, the brown tree snake ( Boiga irregularis ) has extirpated native...
- 5 December 2013 11:26 am , Vol. 342 , #6163
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Make Way for Superfrog
28 May 2008 (All day)
X-Men fans rejoice: Wolverine has come to life, as a frog. When the comic book warrior faces a fight, metallic blades spring forth from his hand. A new study concludes that certain African frogs are similarly equipped, having sharp, claw-shaped bones that pierce through their own fingertips when the animal is threatened.
More than 100 years ago, scientists observed the mysterious bony appendages in museum specimens of the Arthroleptidae frog family, but they had no idea what to make of them. Some speculated that the protrusions were an artifact of the preservation process. Harvard University biologists David Blackburn decided to solve the mystery once and for all after having the frequent misfortune of being injured by the amphibians while doing field research in Cameroon. "The frogs will start kicking and drag these claws against your skin," he says. "I've gotten bloody scratches from them many a time."
Due to strict government regulations on removing live animals from Cameroon, Blackburn's team had to do their anatomical studies on preserved museum specimens. In addition to the talon-shaped finger bones others had seen, the researchers found a small bony nodule nestled in the tissue just beyond the frog's fingertip. When sheathed, each claw is anchored to the nodule with tough strands of collagen, but, as Blackburn had discovered firsthand, when the frog is grabbed or attacked, the frog breaks the nodule connection and forces its sharpened bones through the skin.
This bizarre skeletal feature is found in only 12 species within the Arthroleptidae family, Blackburn's team reports online this week in Biology Letters. Why some members of this family developed such a dramatic form of defense is still a mystery, though the researchers speculate that because amphibians have a remarkable flair for regeneration, the African frogs may heal up afterward, just like Wolverine.
Amphibian researcher and biologist David Wake of the University of California, Berkeley, says that this type of weaponry appears to be unique in the animal kingdom. But David Cannatella, a herpetologist at the University of Texas, Austin, questions whether the bony protrusions are meant for fighting. They could allow a frog's feet "to get a better grip on whatever rocky habitat they might be in," he says.