Nonnative pythons, like this one, are invading the Florida Everglades. As a top predator, the snakes have crippled the populations of rabbits, raccoons and other animals. Joe Raedle/Getty Images hide caption

itoggle caption Joe Raedle/Getty Images

New advice on housing lab rodents has left research centers confused about compliance and worried about the costs. Tom Gannam/AP hide caption

itoggle caption Tom Gannam/AP