February 29, 2008Valerie Clark does a "taste and toxicity test" on a green mantella frog at a mango plantation in northern Madagascar in December 2007.

The U.S. biologist, who studies the evolution of frogs' chemical defenses, often can't wait to get to the lab to do her researchso she relies on her tongue instead. (Read full story.)

"I don't recommend this," she cautioned, "because if you lick the wrong frog it can be very bad."

Her methods may be unconventional, but her research comes at a critical timemany frog species are in decline worldwide, victims of habitat destruction and a deadly fungus called chytrid. (Related news: "Frog Extinctions Linked to Global Warming" [January 12, 2006].)

The World Conservation Union estimates that a third of all amphibian species are currently threatened with extinction.

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