Freaky frogs.

If you found a onelegged frog, you'd probably feel bad for the frog. But David Hoppe, a scientist in Minnesota who's found hundreds of deformed frogs recently, is more worried about the environment--and how it might affect other living things.

"Frogs are sensitive enough [to environmental change] that they'll show its effects almost immediately," says Hoppe, a herpetologist, or scientist who studies amphibians. The deformed frogs may be a sign of increasing radiation from the Sun, water pollution, or even a bacterial epidemic.

Hoppe is particularly concerned because the number of deformed frogs is rising. In 1994, Hoppe found only a few in one or two areas in Minnesota. This past summer, the freaky frogs showed up in more than 100 sites.

"There's no evidence of chromosome damage," Hoppe explains. That means the frogs didn't inherit the defects from their parents. Instead, Hoppe thinks the defects developed while the frogs were still eggs or tadpoles.

The root of the problem, he suspects, is the water in which the frogs live. About 50 percent of mink frogs, which spend most of their time in water, have at least one abnormality. In contrast, he adds, "the land-dwelling frogs seem to be least affected."

Why would water matter? Frogs have thin, highly permeable skin. So contaminated water could easily enter their bodies. But so far, researchers haven't found excessive amounts of pollutants known to cause abnormalities. And only a few frogs have shown evidence of chemicals or parasites in their tissues.

It may be months, or even years, before scientists solve the frog mystery. Meanwhile, other researchers are on the hunt for more deformed frogs. If you find oddlooking amphibians in your area, contact the "Friends of Frogs" hotline at [phone].