The keys for polar bear cages are seen at a polarland in Harbin, capital of northeast China's Heilongjiang Province, July 30, 2015. Polar bear trainers, joked as the most dangerous profession in town by their colleagues, have to live and work with the polar bears weighing more than 500 kilograms and run at over 40 kilometers per hour maximum. Their work consists of measuring the bear's temperature, feeding and transferring. Despite the danger, the trainers at Harbin Polarland has established affinities with the beasts. (Xinhua/Wang Kai)
