Chicago's resident polar bear, Anana, was kept indoors Monday because of record-low temperatures from Polar Vortex.

Lincoln Park Zoo spokeswoman Sharon Dewar says that while the below zero weather might be comparable to what polar bears experience in the wild, the 14-year-old female bear Anana doesn't have a thick layer of fat that bears typically from eating seals and whale carcasses.

"We don't create that fat layer in zoo animals because that would normally not be something they would be comfortable with."

Anana has been mostly in her indoor enclosure, where temperatures are 40 F (4 C), and she will be allowed to venture outside Tuesday.