Is a polar bear an extremophile?

No, a polar bear is not classified as an extremophile. Extremophiles are organisms that thrive in extreme environmental conditions, such as extreme temperatures, acidity, or salinity. While polar bears are well adapted to their cold Arctic habitat and possess unique physiological traits to survive in such conditions, they do not inhabit environments that are extreme in the same way that extremophiles do. Instead, they are specialized mammals adapted to a specific ecological niche.