Emperors, native to the Antarctic, are the tallest—they can reach nearly four feet—and heaviest of all penguins and can endure the harshest weather of any species. (The average temperature in Antarctica is minus sixty-two degrees Fahrenheit!) These flightless birds can dive as deep as 1,850 feet and remain underwater for up to twenty-two minutes. They only breed during the winter, unlike other birds, and their self-sacrifice, parenting skills, and loyalty to their mates is legendary. They keep warm during the winter by huddling together and take turns in the warm center of the group. After a brief courtship, male and female birds take turns keeping their eggs warm underneath a layer of feathered skin. (While one keeps the egg warm, the other makes the fifty-mile trek back to the ocean to feed in icy waters.) Emperor penguins usually just eat krill (shrimp-like crustaceans) but also like small fish and squid. They usually live twenty but sometimes make it to forty.