Orca or killer whales are the largest members of the dolphin family. They are a cosmopolitan species, found in all of the world’s oceans. This dramatic photo shows an orca hunting a Weddell seal in the Southern Ocean. The seal has attempted to save itself by hiding on an ice floe, but orcas, one of the most intelligent of mammals, are adept at tipping or flipping floes. Photo courtesy of the National Science Foundation Office of Polar Programs / Robert Pitman.