Eight-legged frogs give biologists the willies. They
say the deformed amphibians – like canaries in a mine – indicate
environmental problems that could affect the two-legged as well. So
when extra-legged Pacific tree frogs surfaced in three westside
Oregon communities last summer, researchers took
notice.
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
This article appeared in the print edition of the magazine with the headline Frogs sport too many legs.
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