A curious paradox has befallen the world's amphibians, and UC Berkeley scientists are tracking it day by day.

New species of frogs and toads, newts and salamanders, and wormlike critters called caecilians are being discovered all the time as biologists take to the field in the world's last unexplored places.

At the same time, naturalists say, more and more species of amphibians are dying off in what appears to be an oncoming mass extinction - particularly for frogs.

"In all the doom and gloom about the species that are threatened and the populations that are declining, we're finding new ones at an even faster rate," said David Wake, a UC Berkeley biologist who has long combed the continents discovering new amphibians - particularly salamanders - and was among the first to warn that many species are going extinct.

Wake and his colleagues have created an online catalog of the lives and fates of all amphibians, called AmphibiaWeb. The site reported with fanfare this week that 7,000 amphibian species have been recorded in the world, up from about 5,000 a dozen years ago.

In the past two weeks alone, biologists reported the discovery of 18 new species, said Wake, director of AmphibiaWeb.org. One of them is a little green glass frog, Centrolene sabini, discovered in Peru by a young naturalist from San Francisco State, Alessandro Catenazzi.

"It was a rainy night in January," Catenazzi wrote in an e-mail from his exploration site 10,000 feet high in the cloud forest of the Andes, "and I was just walking along a road looking for frogs when I heard C. sabini's intriguing call. This calling male was perched over a precipice above the stream, but luckily I was able to reach the branch and record the call."

Frogs dominate the Berkeley-based project, with 6,179 frog species reported. Newts and salamanders trail, with 631 species reported, and the caecilians come last, with only 190 species known to biologists.

The caecilians are obscure critters indeed: legless and nearly blind, they travel like worms and snakes, use their bony heads to burrow underground, and reproduce in varied bizarre ways. Three of the species are considered at risk of vanishing.

The International Union for the Conservation of Nature in Switzerland, which tracks the status of all the world's plants and animals, reported on its Red List this year that 41 percent of the world's amphibians are threatened with extinction.

Fifteen years ago, the organization reported that only 18 species of amphibians were "critically endangered." This year the count is 507 species.

"It's deeply ironical and paradoxical that so many amphibians are going extinct right in front of our eyes, while at the same time, more and more biologists are taking the last chance to explore in the last wild places and discovering more and more new species of amphibians," Wake said.

The disappearance of many frogs has been documented in the Sierra, due primarily to an epidemic of the toxic chytrid fungus that is spreading across every continent in the world.

Other threats to amphibians include development on habitat lands, pollution, pesticides and the introduction of species that overwhelm existing populations, the AmphibiaWeb scientists say.
