What's It Like to Manage 2,700 Picky Eaters? Guest: Mike Maslanka, Senior Nutritionist and Head of the Department of Nutrition Science, Smithsonian’s National Zoo  The Smithsonian’s National Zoo is home to 2,700 animals, and each one requires their own special diet. How do you juggle so many different diets?  Bringing Back the Northern White Rhino Guest: Barbara Durrant, Director, Reproductive Sciences, San Diego Zoo Global It might sound like Jurassic Park, but scientists at the San Diego Zoo are using cells from a frozen zoo to try to bring back the functionally extinct northern white rhino.