Polar Bears (Ursus maritimus) are one of the largest bears, weighing as much as 1,500 lbs. The Polar Bear is currently listed as threatened under the US Endangered Species Act. Because they are at the top of the arctic food chain and depend heavily on sea ice for their survival, they have become a key indicator species in the fight against climate change.
For more information go to:
http://animals.nationalgeographic.com/animals/mammals/polar-bear/
http://www.polarbearsinternational.org/