An iceberg is pictured in the western Antarctic peninsula, on March 04, 2016.
Like seals and whales, penguins eat krill, an inch-long shrimp-like crustacean that forms the basis of the Southern Ocean food chain. But penguin-watchers say the krill are getting scarcer in the western Antarctic peninsula, under threat from climate change and fishing. / AFP / EITAN ABRAMOVICH (Photo credit should read EITAN ABRAMOVICH/AFP via Getty Images)