Overview/Amphibian Ailments" data-pin-do="buttonBookmark">
ALARMING LEGS: Ecologist Andrew R. Blaustein eyes malformed Pacific tree frogs collected from farm ponds in northwestern Oregon.
Overview/Amphibian Ailments Image: FRANS LANTING Minden Pictures
One hot summer day in 1995 eight middle school children planning a simple study of wetland ecology began collecting leopard frogs from a small pond near Henderson, Minn. To their astonishment, one captured frog after another had five or more hind legs, some twisted in macabre contortions. Of the 22 animals they caught that day, half were severely deformed. A follow-up search by pollution-control officials added to the gruesome inventory. Occasional frogs in the pond had no hind limbs at all or had mere nubbins where legs should be; others had one or two legs sprouting from the stomach. A few lacked an eye.
The story seized national media attention and raised many questions--among them, was this an isolated occurrence or one facet of a widespread trend? And what caused the deformities? As researchers elsewhere in the country began investigating their local amphibian populations, it became clear that this bizarre collection of ailments was not confined to Minnesota. Since 1995, malformations have been reported in more than 60 species, including salamanders and toads, in 46 states. In some local populations 80 percent of the animals are afflicted. International reports show that this phenomenon extends beyond the U.S. Surprising numbers of deformed amphibians have been found in Asia, Europe and Australia as well. Worldwide, extra legs and missing legs are most common.