To say that Jim Vlna (pronounced VUL-nuh) has spent his life in the zoo is really no exaggeration. Vlna has just retired as director of the Knoxville Zoo after almost 22 years. Prior to that, he spent 30 years with the Brookfield Zoo in Illinois, starting work there when he was 13 years old. WUOT's Morning Edition host Chrissy Keuper speaks with Vlna about some of the changes he’s seen in zoological parks over the years, including some fairly recent adjustments in philosophy.