There are 18 species of penguins, all living in the Southern Hemisphere and all adapted to their particular conditions, habitats and lifestyles. The differences between them are small, size and colour patterns being the most significant. They are all recognisable as penguins though, with their short fat feet set well back on the body, stubby wings adapted to swimming rather than flying, bodies which are streamlined for swimming and encased in thick layers of fat and feathers to protect them from the cold. All penguins belong to the Avian Order Sphenisciformes. Because they are so similar and closely related, all eighteen species are classified in one family as well, the Spheniscidae.
All penguins have black backs and white stomachs. Differences in colouration occur mostly around the head. All penguins feed in the ocean on fish, squid and krill and all have to come ashore to breed, lay their eggs and raise their young. Usually the males are larger than the females. Because their feet are so far back for swimming, all penguins are rather clumsy and comical when walking on land. They are social birds and noisy, with loud, braying voices to help them locate mates and offspring in crowded rookeries. And all penguins must cope with fierce ocean predators such as sharks, killer whales and leopard seals in order to survive.
Most penguin species are found in the cold, food-rich waters surrounding Antarctica. Some breed on the ice while others make their rookeries on windswept Antarctic beaches and subantarctic islands. A few are found further north: jackass penguins of Africa, Little Blue penguins in Australia and the Galapagos Penguin, which due to the cold Antarctic currents is able to breed further north than any other penguin species. The oceans of the tropical regions are too barren to feed penguins and too hot for their fatty, densely feathered bodies to cope with and this has acted as a barrier to their migration to the Northern Hemisphere and the Arctic. That is the only reason that polar bears don't eat penguins. If they had the choice, they would certainly appreciate these fat little bundles of nutrition.
Penguins are grouped into six genera. Only one genus has a single species and that is Megadyptes antipodes, the Yellow-Eyed Penguin. On the basis of this classification, the Yellow-Eyed Penguin is the most different of all the penguins. It is found only in New Zealand and is the rarest penguin species. Its bright yellow eyes and light coloured head also set it apart from other penguin species.
The smallest penguins belong to the genus Eudyptula: the Little Blue or Fairy Penguin, Eudyptula minor and the White-Flippered Penguin, Eudyptula albosignata. These tiny penguins live in New Zealand and the Fairy Penguin also occurs in Australia. They nest in burrows and differ from other penguins by having no distinctive markings on their faces, which are bluish rather than black. They weigh in at only 1 -2 kg.
My favourite group of penguins are the Crested Penguins, genus Eudyptus. There are six species of Crested Penguins: the Fjordland Crested (E. pachyrhynchus), Snares Crested (E. robustus), Erect Crested ( E. sclateri), Rockhopper (E. chrysocome), Macaroni (E. chrysolophus) and the Royal (E. schlegeli). All are found on the subantarctic Islands that dot the great Southern Ocean and all are characterised by wonderful yellow-feathered eyebrows which they use expressively to show their emotions and moods. They are medium sized penguins weighing between 2.5 to 5 kg and are very social and gregarious.
The fourth group of Penguins are known as the Pygoscelids and there are only three species: the Adelie (Pygoscelis adeliae), the Gentoo (P. papua) and the Chinstrap (P. antarctica). These are medium-sized penguins of 4-5 kgs and they lack the distincive yellow eyebrows of the Eudyptes penguins. The Adelie is the most abundant and widely distributed penguin species found on the Antarctic continent and also the most photographed. Its most distinguishing feature is a white eye ring. The Gentoo penguin is also found on the Antarctic continent and it has white patches on the head and a yellow-orange bill to distinguish it from the Adelie. The Chinstrap, which has a black line along its chin that gives it its name also breads on the Antarctic Peninsula and also some of the subantarctic islands in the South Atlantic. It is often found in colonies of Gentoos and Adelies.
The fifth group of penguins are the Spheniscids or Four-ringed penguins. These medium-sized penguins, weighing 3-5 kg, are distinguished by white lines breaking up the black feathers of their heads and they are found further north than any of the other penguins. The African Black-footed or Jackass Penguin (Spheniscus demersus) was the first penguin to be seen by Europeans because it lives along the southern shores of Africa. It nests in burrows and has become accostumed to the presence of humans. The Magellanic Penguins (S. magellanicus) are the largest of the four-ringed penguins and live along the coast of Patagonia in Argentina. Like the African Jackass, they bray like donkeys so they are also known as Jackass Penguins. Further north, the Peruvian or Humbolt Penguin (S. humboldti) lives and breeds in small colonies along the west coast of South America. The last member of this group is the Galapagos Penguin (S. mendiculus) and it is the only penguin to be found in the equatorial regions, surviving there only because of the cold and fertile Humboldt Current, which keeps the Galapagos cool enough for this Antarctic immigrant and supplying it with enough fish to survive.
Last but certainly not least are the two largest penguins, the Emperor and the King. These two have distinctive yellow and orange patches on their necks and weigh in at 30-40 kg for the Emperor and 20 kg for the King. They belong to the genus Aptenodyptes. The Emperor (A. forsteri) is a truly Antarctic species and is known from the movie March of the Penguins for the incredible journeys the birds make to rear their young during the long, cold Antarctic night. They certainly have to be the toughest species of a very tough family of birds. King Penguins (A. patagonica), on the other hand, are found on subantarctic islands right around the Southern Ocean.
It is obvious that the differences between penguins are much smaller than their similarities. All species are immediately recognisable as penguins and differ only in size and some slight differences in colours and patterns. They are so different from other birds because they have committed themselves fully to life in the sea and have given up flight altogether. The only thing that ties them to the land is their need to lay their eggs and raise their chicks there.