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

A veiled chameleon (Chamaeleo calyptratus) at the Rolling Hills Wildlife Adventure outside Salina, Kan. Joel Sartore hide caption

itoggle caption Joel Sartore

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