Salamanders have recently been struck by a dangerous new fungus, but they are not the only amphibians facing challenges to their very existence as a species.

European and American salamanders are being wiped out by a fungus from Asia, which has recently arrived on the European continent. Every red-eyed Newt exposed to the fungus perishes from the infection, which biologists believe may have reached Europe through the international pet trade. Batrachochytrium salamandrivorans may have traveled with Asian newts, popular with salamander owners.

Amphibians worldwide are threatened with emerging diseases, as well as loss of habitats. A total of 1,856 amphibian species are currently considered threatened around the globe, nearly one-third of all varieties.

Iridoviridae viruses have been implicated in the deaths of common frogs and Sonora tiger salamanders around the globe. Yellow-legged frogs are suffering from the effects of a metazoan agent, and researchers are uncertain how common the parasitic animals are in nature. Boreal toads are seeing their population decimated by the bacteria Aeromonas hydrophila, which may have been responsible for a massive die-off of the animals in 1979.

Ranaviruses have been shown to be responsible for dieoffs of several amphibian species. Symptoms of infection include lethargy and organ failure, making the virus difficult to track and manage. These organisms can be transmitted through cannibalism, among other paths to infection.

"Amphibians have existed on earth for over 300 million years, yet in just the last two decades there have been an alarming number of extinctions, nearly 168 species are believed to have gone extinct and at least 2,469 (43%) more have populations that are declining. This indicates that the number of extinct and threatened species will probably continue to rise," Amphibiaweb, a group dedicated to protecting amphibians around the world, reported on their Web site.

Diseases are not even the most dangerous threat to amphibians around the globe, according to the International Union for Conservation of Nature and Natural Resources (IUCN).

"Habitat loss and degradation are by far the greatest threat to amphibians at present, affecting nearly 4,000 species. The number of species impacted by habitat loss and degradation is almost four times greater than the next most common threat, pollution," the IUCN Red List of Threatened Species reported.

Not all challenges to amphibians result in death to the animals. A trematode infestation is the likely cause of massive leg deformities among Pacific treefrogs, as well as other species of amphibians.

Amphibian diversity is greatest in the tropics, with 932 species living in Brazil. In the United States, that number is a mere 297. As habitat there is lost to human encroachment and development, the diversity of amphibians could continue to decline.

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