Flourishing frogs. (Life News).

While alarmed biologists struggle to understand why frogs, toads, and other cold-blooded, egg-laying amphibians are declining worldwide, one research team is scrambling to identify more than 100 just-found frog species. They were discovered in the last shreds of rainforest--a mere 750 square kilometer (290 sq mile) area--on the island of Sri Lanka. "This brings the number of frog species on the island to at least 140," says lead researcher Christopher Schneider of Boston University.

About 5,400 known amphibian species exist worldwide. "It's certainly not unusual to find new frog species," says Schneider's colleague Karen Warkentin. But finding so many at once is rare indeed. The Sri Lankan frogs range from long-toed tree frogs to bright marble-size specimens that dart about in leaf litter on the forest floor. They're stunning examples of adaptive radiation, or different species originating from a common ancestor, says Schneider. Over time, new species evolved as the frogs adapted new body shapes to survive in different habitats.

Why are these frogs flourishing while so many others are being decimated by environmental pollutants? The answer, says Schneider, might relate to the way they develop. Unlike most frogs, most of the Sri Lankan specimens lay eggs that incubate on land until the fully formed froglets hatch, entirely skipping the aquatic tadpole stage. Many of the factors--pollutants and lethal fungus--thought to be killing off frogs are most destructive to water-based young. Will other frogs catch on?--K.M.