On a hot Friday at the Pittsburgh Zoo and Aquarium, both animals and visitors found ways to stay cool, from shady spots to frozen treats.For Snowflake, the zoo's polar bear, cooling off meant taking a swim in her pool, which is kept at a crisp 58 degrees."She has an air-conditioned den in the back if she so chooses to use that," Zoo President Dr. Jeremy Goodman said.He said that most of the zoo's animals have options to stay cool, and their bodies are well-adapted to handle the heat."Their...