Asian elephant Shanthi plays in an enclosure at the Elephant Community Center during the unveiling of the major expansion of the elephant house at the Smithsonian's National Zoo in 2013.
Manuel Balce Ceneta/AP
Giant panda Mei Xiang, together with her cub Bao Bao at the National Zoo in 2014. As of Saturday, Bao Bao now has another sibling: Her mother just gave birth to a cub.
Chip Somodevilla/Getty Images