Penguins are a group of aquatic, flightless birds living almost exclusively in the Southern Hemisphere. Most penguins feed on krill, fish, squid, and other forms of sealife caught while swimming underwater. They spend half of their life on land and half in the oceans. Penguins are popular around the world for their unusually upright, waddling pace and lack of fear of humans. Their striking black and white plumage is often likened to a tuxedo suit.