Early Antarctic explorers actually thought penguins were fish and classified them accordingly. In fact, as birds, they are superbly designed for their job, flying underwater with great skill. Their compact bodies have a breastbone that makes an excellent keel and they have massive paddle muscles to propel them at speeds up to 25 miles per hour.
Of the 17 species of penguins, only four breed on the Antarctic continent itself: the Adelie, the Emperor, the Chinstrap and the Gentoo penguins. Most other species are found within the subantarctic regions which includes many coastal islands. Penguins are also found as far north as the Galapagos Islands, straddling the Equator.
Penguins are true flightless birds. Some species spend as much as 75% of their lives at sea, yet they all breed on land or sea-ice attached to land. To withstand the harsh conditions of the Antarctic, their bodies are insulated by a thick layer of blubber and a dense network of waterproof plumage.
Penguins’ bones are solid and heavy, which help them to remain submerged and reduce the energy needed for pursuit diving. Some species can reach depths of 1000 feet or more and stay submerged for up to 25 minutes, though most prefer shorter, shallower dives.
Penguins are now enjoying a population boom. Their increasing numbers can be partly attributed to the over-fishing of baleen whales in the past which has resulted in a super-abundance of krill, a key species in the Antarctic ecosystem. In addition to krill, penguins feed heavily on fish, squid, and other small crustaceans.
Penguins generally breed in large, dense colonies called ‘rookeries’, some with 180,000 or more birds. The sights, smells, and noise of one of these huge colonies are unforgettable. Most penguins build nests of stone and there they incubate one or two eggs.
Natural enemies of the penguin include seals, Killer whales, and, in the case of young chicks and eggs, several species of seabirds. Healthy adult penguins have no predators on land, so they have no natural fear of humans.