These frogs don't turn into princes.

A disturbing wildlife phenomenon has turned up throughout the Great Lakes region, from Minnesota to Quebec: deformed frogs. Since August of 1995, researchers have found malformed frogs at more than 174 sites in 54 of Minnesota's 87 counties, prompting researchers to try and solve the mystery.

Last summer, after record reports of leopard frog abnormalities by Le Sueur elementary school students studying wildlife on nearby wetlands, University of Minnesota researchers and state pollution officials conducted some of their own studies and also found "hideously deformed" frogs with missing eyes and legs, misshapen or extra legs, or rearranged organs or extremities. Some specimens were found with eyes in their throat, webbed legs or legs which split into two sections midway down. Early evidence is pointing toward water contaminants located near frog breeding sites.

Dr. Robert McKinnell of the University of Minnesota, who's been studying frogs since 1958, says the discovery of such deformities is important to humans because frogs are a "sentinel" species, meaning they have metabolic functions similar to our own and may be indicating potential trouble ahead for humans.

According to hepetologist David Wake of the University of California, Berkeley, "Amphibians are excellent indicators of environmental stress. Since they live in both aquatic and terrestrial systems, they might tell us faster that something is wrong. They're an early warning system?

Overall, frog populations have been dwindling at an alarming rate in the last 10 years, due mainly to decreasing habitat, ozone depletion (frog skin is acutely sensitive to ultraviolet rays), acid rain and an increase in predators. But scientists say these factors cause death in the species, not deformities, forcing researchers to ponder which of the numerous chemicals or heavy metals polluting American waterways are the culprit.

So far, scientists have yet to pinpoint a cause. Some biologists, like Dr. Stan Sessions of Hartwick College, attribute the deformities to a reptilian parasite which burrows into tadpole bodies while they're developing, sometimes causing multiple legs to form. But researchers, like Judy Helgin, lead researcher at the Minnesota Pollution Control Agency, doubt the explanation, saying that the abnormalities were inconsistent and too numerous and varied to be attributed to parasites. Mike Lanoo of the Declining Amphibian Population Task Force suspects methporene, used in mosquito control.

McKinnell wasn't alarmed by early reports, because he says frogs have a small number of birth defects naturally - until he found one site with a 96 percent frog deformity rate. Herpetologists like McKinnell agree that frogs are enormously vulnerable during early life cycle changes to hormonal variations, which may be triggered by pesticides and other toxins, creating an estrogen-mimicking effect which disturbs a frog's development.

The students who discovered the deformities near the Minnesota River have since created A Thousand Friends of Frogs, and are trying to get others involved in documenting frog deformities in hopes that researchers will find an answer. CONTACTS: A Thousand Friends of Frogs, Center for Global Environmental Education, Hamlin University, 1536 Hewitt Avenue, St. Paul, MN 55104/[phone]; Minnesota Pollution Control Agency, 520 Lafayette Road, St. Paul, MN 55155/[phone].