No one knew what to make of the phenomenon until a couple of 10-year-old schoolboys from Aloha, Ore., Fed-Ex'd one of the dime-sized frogs to Stan Sessions, an amphibian expert at Hartwick College in New York. Now, Sessions' close examination of the eight-legged specimen has yielded a few answers.
The growths weren't genetically caused, he says. Instead, a trematode parasite burrowed into the fleshy limb buds of tadpoles, disrupting normal cell growth. That rules out chemical pollutants and other human factors as primary causes, but the question remains: Why so many trematodes?
It could be a natural cycle, says Sessions, although pesticides may also be to blame. The biologist is looking for more clues in pond snails that often host the parasite's larvae.
* Sarah Dry