Monstars: Prophecy (1979)

The giant mutant bear from the 1979 environmental horror flick Prophecy. According to this movie mercury poisoning can make women give birth to fish or cats or other lower forms of animals, and bears turn into crazy tumor covered half-furred mutants that wander the woods doing things like this:





Decent movie even though the environmental message is pretty heavy handed and some of the science is hilarious (ie. those above discriptions of what exposure to mercury will do).