Penguin

Penguin

Overview
Penguins are a group of aquatic
Aquatic animal
An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...

, flightless
Flightless bird
Flightless birds are birds which lack the ability to fly, relying instead on their ability to run or swim. They are thought to have evolved from flying ancestors. There are about forty species in existence today, the best known being the ostrich, emu, cassowary, rhea, kiwi, and penguin...

 bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s living almost exclusively in the southern hemisphere
Southern Hemisphere
The Southern Hemisphere is the part of Earth that lies south of the equator. The word hemisphere literally means 'half ball' or "half sphere"...

, especially in Antarctica. Highly adapted for life in the water, penguins have countershaded
Countershading
Countershading, or Thayer's Law, is a form of camouflage. Countershading, in which an animal’s pigmentation is darker dorsally, is often thought to have an adaptive effect of reducing conspicuous shadows cast on the ventral region of an animal’s body...

 dark and white plumage, and their wings have become flippers
Flipper (anatomy)
A flipper is a typically flat limb evolved for movement through water. Various creatures have evolved flippers, for example penguins , cetaceans A flipper is a typically flat limb evolved for movement through water. Various creatures have evolved flippers, for example penguins (also called...

. Most penguins feed on krill
Krill
Krill is the common name given to the order Euphausiacea of shrimp-like marine crustaceans. Also known as euphausiids, these small invertebrates are found in all oceans of the world...

, fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

, squid
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...

, and other forms of sealife caught while swimming underwater. They spend about half of their lives on land and half in the oceans.

Although all penguin species are native to the southern hemisphere, they are not found only in cold climates, such as Antarctica.
Discussion
Ask a question about 'Penguin'
Start a new discussion about 'Penguin'
Answer questions from other users
Full Discussion Forum
 
Unanswered Questions
Encyclopedia
Penguins are a group of aquatic
Aquatic animal
An aquatic animal is an animal, either vertebrate or invertebrate, which lives in water for most or all of its life. It may breathe air or extract its oxygen from that dissolved in water through specialised organs called gills, or directly through its skin. Natural environments and the animals that...

, flightless
Flightless bird
Flightless birds are birds which lack the ability to fly, relying instead on their ability to run or swim. They are thought to have evolved from flying ancestors. There are about forty species in existence today, the best known being the ostrich, emu, cassowary, rhea, kiwi, and penguin...

 bird
Bird
Birds are feathered, winged, bipedal, endothermic , egg-laying, vertebrate animals. Around 10,000 living species and 188 families makes them the most speciose class of tetrapod vertebrates. They inhabit ecosystems across the globe, from the Arctic to the Antarctic. Extant birds range in size from...

s living almost exclusively in the southern hemisphere
Southern Hemisphere
The Southern Hemisphere is the part of Earth that lies south of the equator. The word hemisphere literally means 'half ball' or "half sphere"...

, especially in Antarctica. Highly adapted for life in the water, penguins have countershaded
Countershading
Countershading, or Thayer's Law, is a form of camouflage. Countershading, in which an animal’s pigmentation is darker dorsally, is often thought to have an adaptive effect of reducing conspicuous shadows cast on the ventral region of an animal’s body...

 dark and white plumage, and their wings have become flippers
Flipper (anatomy)
A flipper is a typically flat limb evolved for movement through water. Various creatures have evolved flippers, for example penguins , cetaceans A flipper is a typically flat limb evolved for movement through water. Various creatures have evolved flippers, for example penguins (also called...

. Most penguins feed on krill
Krill
Krill is the common name given to the order Euphausiacea of shrimp-like marine crustaceans. Also known as euphausiids, these small invertebrates are found in all oceans of the world...

, fish
Fish
Fish are a paraphyletic group of organisms that consist of all gill-bearing aquatic vertebrate animals that lack limbs with digits. Included in this definition are the living hagfish, lampreys, and cartilaginous and bony fish, as well as various extinct related groups...

, squid
Squid
Squid are cephalopods of the order Teuthida, which comprises around 300 species. Like all other cephalopods, squid have a distinct head, bilateral symmetry, a mantle, and arms. Squid, like cuttlefish, have eight arms arranged in pairs and two, usually longer, tentacles...

, and other forms of sealife caught while swimming underwater. They spend about half of their lives on land and half in the oceans.

Although all penguin species are native to the southern hemisphere, they are not found only in cold climates, such as Antarctica. In fact, only a few species of penguin live so far south. Several species are found in the temperate
Temperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...

 zone, and one species, the Galápagos Penguin
Galapagos Penguin
The Galapagos Penguin is a penguin endemic to the Galapagos Islands. It is the only penguin that lives north of the equator in the wild; it can survive due to the cool temperatures resulting from the Humboldt Current and cool waters from great depths brought up by the Cromwell Current...

, lives near the equator.

The largest living species is the Emperor Penguin
Emperor Penguin
The Emperor Penguin is the tallest and heaviest of all living penguin species and is endemic to Antarctica. The male and female are similar in plumage and size, reaching in height and weighing anywhere from . The dorsal side and head are black and sharply delineated from the white belly,...

 (Aptenodytes forsteri): adults average about 1.1 m (3 ft 7 in) tall and weigh 35 kg (75 lb) or more. The smallest penguin species is the Little Blue Penguin
Little Penguin
The Little Penguin is the smallest species of penguin. The penguin, which usually grows to an average of in height and in length , is found on the coastlines of southern Australia and New Zealand, with possible records from Chile.Apart from Little Penguins, they have several common names...

 (Eudyptula minor), also known as the Fairy Penguin, which stands around 40 cm tall (16 in) and weighs 1 kg (2.2 lb). Among extant penguins, larger penguins inhabit colder regions, while smaller penguins are generally found in temperate or even tropical climates (see also Bergmann's Rule
Bergmann's Rule
Bergmann's rule is an ecogeographic principle that states that within a broadly distributed genus, species of larger size are found in colder environments, and species of smaller size are found in warmer regions. Although originally formulated in terms of species within a genus, it has often been...

). Some prehistoric species attained enormous sizes, becoming as tall or as heavy as an adult human. These were not restricted to Antarctic regions; on the contrary, subantarctic
Subantarctic
The Subantarctic is a region in the southern hemisphere, located immediately north of the Antarctic region. This translates roughly to a latitude of between 46° – 60° south of the Equator. The subantarctic region includes many islands in the southern parts of the Indian Ocean, Atlantic Ocean and...

 regions harboured high diversity, and at least one giant penguin occurred in a region not quite 2,000 km south of the equator
Equator
An equator is the intersection of a sphere's surface with the plane perpendicular to the sphere's axis of rotation and containing the sphere's center of mass....

 35 mya, in a climate decidedly warmer than today.

Etymology


The etymology of the word "penguin" is highly disputed. The English word is not apparently of French
French language
French is a Romance language spoken as a first language in France, the Romandy region in Switzerland, Wallonia and Brussels in Belgium, Monaco, the regions of Quebec and Acadia in Canada, and by various communities elsewhere. Second-language speakers of French are distributed throughout many parts...

, nor of Breton
Breton language
Breton is a Celtic language spoken in Brittany , France. Breton is a Brythonic language, descended from the Celtic British language brought from Great Britain to Armorica by migrating Britons during the Early Middle Ages. Like the other Brythonic languages, Welsh and Cornish, it is classified as...

 or Spanish
Spanish language
Spanish , also known as Castilian , is a Romance language in the Ibero-Romance group that evolved from several languages and dialects in central-northern Iberia around the 9th century and gradually spread with the expansion of the Kingdom of Castile into central and southern Iberia during the...

 origin (both attributed to the French word pingouin "auk
Auk
An auk is a bird of the family Alcidae in the order Charadriiformes. Auks are superficially similar to penguins due to their black-and-white colours, their upright posture and some of their habits...

"), but first appears in English or Dutch.

Some dictionaries suggest a derivation from Welsh
Welsh language
Welsh is a member of the Brythonic branch of the Celtic languages spoken natively in Wales, by some along the Welsh border in England, and in Y Wladfa...

 pen "head" and gwyn "white", including the Oxford English Dictionary
Oxford English Dictionary
The Oxford English Dictionary , published by the Oxford University Press, is the self-styled premier dictionary of the English language. Two fully bound print editions of the OED have been published under its current name, in 1928 and 1989. The first edition was published in twelve volumes , and...

, the American Heritage Dictionary, the Century Dictionary
Century Dictionary
The Century Dictionary and Cyclopedia was one of the largest encyclopedic dictionaries of the English language. The first edition was published from 1889 to 1891 by The Century Company of New York, in six, eight, or ten volume versions in 7,046 pages with some 10,000 wood-engraved illustrations...

 and Merriam-Webster
Merriam-Webster
Merriam–Webster, which was originally the G. & C. Merriam Company of Springfield, Massachusetts, is an American company that publishes reference books, especially dictionaries that are descendants of Noah Webster’s An American Dictionary of the English Language .Merriam-Webster Inc. has been a...

, on the basis that the name was originally applied to the great auk
Great Auk
The Great Auk, Pinguinus impennis, formerly of the genus Alca, was a large, flightless alcid that became extinct in the mid-19th century. It was the only modern species in the genus Pinguinus, a group of birds that formerly included one other species of flightless giant auk from the Atlantic Ocean...

, which had white spots in front of its eyes (although its head was black).

An alternative etymology, found in a few English dictionaries, links the word to Latin pinguis "fat", from its perceived appearance. This etymology would be improbable if "penguin" were found to have been originally applied to the great auk, as some sources suggest.

A third theory states that the word is an alteration of “pen-wing”, with reference to the rudimentary wings of great auks. This has been criticised for the unexplained nature of the alteration of the word.

Living species and recent extinctions



The number of extant penguin species
Species
In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 is debated. Depending on which authority is followed, penguin biodiversity
Biodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...

 varies between 17 and 20 living species, all in the subfamily Spheniscinae. Some sources consider the White-flippered Penguin
White-flippered Penguin
The White-flippered Penguin is a small penguin about 30 cm tall and weighing 1.5 kg. It gains its name from the white markings on its flippers, unique to the subspecies...

 a separate Eudyptula
Eudyptula
The genus Eudyptula contains two species of penguin. It is found in southern Australia, Tasmania, New Zealand and the Chatham Islands....

 species, while others treat it as a subspecies of the Little Penguin
Little Penguin
The Little Penguin is the smallest species of penguin. The penguin, which usually grows to an average of in height and in length , is found on the coastlines of southern Australia and New Zealand, with possible records from Chile.Apart from Little Penguins, they have several common names...

; the actual situation seems to be more complicated. Similarly, it is still unclear whether the Royal Penguin
Royal Penguin
The Royal Penguin inhabits the waters surrounding Antarctica. Royals look very much like Macaroni Penguins, but have a white face and chin instead of the Macaronis' black visage. They are long and weigh . Males are larger than females...

 is merely a color morph of the Macaroni penguin
Macaroni Penguin
The Macaroni Penguin is a species of penguin found from the Subantarctic to the Antarctic Peninsula. One of six species of crested penguin, it is very closely related to the Royal Penguin, and some authorities consider the two to be a single species...

. The status of the Rockhopper penguins
Rockhopper penguin
The rockhopper penguins are three closely related taxa of crested penguins that have been traditionally treated as a single species and are sometimes split into two or three species. Not all experts agree on the classification of these penguins...

 is also unclear.

Updated after Marples (1962), Acosta Hospitaleche (2004), and Ksepka et al. (2006).

Subfamily Spheniscinae – Modern penguins
  • Aptenodytes
    Aptenodytes
    The genus Aptenodytes contains two extant species of penguins collectively known as "the great penguins".-Taxonomy:...

     – Great penguins
    • King Penguin
      King Penguin
      The King Penguin is the second largest species of penguin at about , second only to the Emperor Penguin. There are two subspecies—A. p. patagonicus and A. p...

      , Aptenodytes patagonicus
    • Emperor Penguin
      Emperor Penguin
      The Emperor Penguin is the tallest and heaviest of all living penguin species and is endemic to Antarctica. The male and female are similar in plumage and size, reaching in height and weighing anywhere from . The dorsal side and head are black and sharply delineated from the white belly,...

      , Aptenodytes forsteri
  • Pygoscelis
    Pygoscelis
    The genus Pygoscelis contains three living species of penguins collectively known as "The Brush-Tailed Penguins". Their appearance - black above, white below - is the stereotypical image of penguins, and so what most people think of when they think of penguins.-Taxonomy:Mitochondrial and nuclear...

     – Brush-tailed penguins
    • Adélie Penguin
      Adelie Penguin
      The Adélie Penguin, Pygoscelis adeliae, is a species of penguin common along the entire Antarctic coast. They are among the most southerly distributed of all seabirds, as are the Emperor Penguin, the South Polar Skua, the Wilson's Storm Petrel, the Snow Petrel, and the Antarctic Petrel...

      , Pygoscelis adeliae
    • Chinstrap Penguin
      Chinstrap Penguin
      The Chinstrap Penguin is a species of penguin which is found in the South Sandwich Islands, Antarctica, the South Orkneys, South Shetland, South Georgia, Bouvet Island and Balleny...

      , Pygoscelis antarctica
    • Gentoo Penguin
      Gentoo penguin
      The Gentoo Penguin , Pygoscelis papua, is easily recognized by the wide white stripe extending like a bonnet across the top of its head and its bright orange-red bill. The gentoo penguin has pale whitish-pink webbed feet and a fairly long tail - the most prominent tail of all penguins. Chicks have...

      , Pygoscelis papua
  • Eudyptula
    Eudyptula
    The genus Eudyptula contains two species of penguin. It is found in southern Australia, Tasmania, New Zealand and the Chatham Islands....

     – Little penguins
    • Little Blue Penguin, Eudyptula minor
    • White-flippered Penguin
      White-flippered Penguin
      The White-flippered Penguin is a small penguin about 30 cm tall and weighing 1.5 kg. It gains its name from the white markings on its flippers, unique to the subspecies...

      , Eudyptula albosignata (provisional)
  • Spheniscus
    Spheniscus
    The banded penguins are the penguins of the Spheniscus genus. There are four living species of penguins known as banded penguins, and all have similar coloration. They are sometimes also known as "Jack-ass penguins" due to their loud locator calls sounding similar to a donkey braying...

     – Banded penguins
    • Magellanic Penguin
      Magellanic Penguin
      The Magellanic Penguin, Spheniscus magellanicus, is a South American penguin, breeding in coastal Argentina, Chile and the Falkland Islands, with some migrating to Brazil where they are occasionally seen as far north as Rio de Janeiro. It is the most numerous of the Spheniscus penguins. Its nearest...

      , Spheniscus magellanicus
    • Humboldt Penguin
      Humboldt Penguin
      The Humboldt Penguin is a South American penguin, that breeds in coastal Peru and Chile. Its nearest relatives are the African Penguin, the Magellanic Penguin and the Galápagos Penguin...

      , Spheniscus humboldti
    • Galapagos Penguin
      Galapagos Penguin
      The Galapagos Penguin is a penguin endemic to the Galapagos Islands. It is the only penguin that lives north of the equator in the wild; it can survive due to the cool temperatures resulting from the Humboldt Current and cool waters from great depths brought up by the Cromwell Current...

      , Spheniscus mendiculus
    • African Penguin
      African Penguin
      The African Penguin , also known as the Black-footed Penguin is a species of penguin, confined to southern African waters. It is known as Brilpikkewyn in Afrikaans, Inguza or Unombombiya in Xhosa, Manchot Du Cap in French and Pingüino Del Cabo in Spanish...

      , Spheniscus demersus
  • Megadyptes
    Megadyptes
    Megadyptes is a genus of penguin which consists of two species, Megadyptes antipodes and the extinct Megadyptes waitaha ....

    • Yellow-eyed Penguin
      Yellow-eyed Penguin
      The Yellow-eyed Penguin or Hoiho is a penguin native to New Zealand. Previously thought closely related to the Little Penguin , molecular research has shown it more closely related to penguins of the genus Eudyptes...

      , Megadyptes antipodes
    • Waitaha Penguin
      Waitaha Penguin
      The Waitaha Penguin is an extinct species of New Zealand penguin discovered in November 2008.The new species was discovered by University of Otago and University of Adelaide scientists comparing the foot bones of 500-year-old, 100-year-old and modern specimens of penguins...

      , Megadyptes waitaha (extinct)
  • Eudyptes
    Eudyptes
    The term crested penguin is the name given to several species of penguin of the genus Eudyptes. The exact number varies between four and seven depending on the authority, and a Chatham Islands species may have become extinct in the 19th century...

     – Crested penguins
    • Fiordland Penguin
      Fiordland Penguin
      The Fiordland Crested Penguin , also known as Tawaki , is a species of crested penguin from New Zealand...

      , Eudyptes pachyrynchus
    • Snares Penguin
      Snares Penguin
      The Snares Penguin , also known as the Snares Crested Penguin and the Snares Islands Penguin, is a penguin from New Zealand...

      , Eudyptes robustus
    • Erect-crested Penguin
      Erect-crested Penguin
      The Erect-crested Penguin is a penguin from New Zealand. It breeds on the Bounty and Antipodes Islands.This is a small-to-medium-sized, yellow-crested, black-and-white penguin, at and weighing . As in all penguin species, the male is slightly larger than the female and the birds weigh the most...

      , Eudyptes sclateri
    • Western Rockhopper Penguin, Eudyptes chrysocome
    • Eastern Rockhopper Penguin
      Eastern Rockhopper Penguin
      The Eastern Rockhopper Penguin although genetically differnt is still often considered as a subspecies of the Southern Rockhopper Penguin.-Distribution:...

      , Eudyptes filholi
    • Northern Rockhopper Penguin
      Northern Rockhopper Penguin
      The Northern Rockhopper Penguin, Eudyptes c. moseleyi, is usually considered a subspecies of rockhopper penguin, although fairly recent studies show evidence of distinction from the Southern Rockhopper Penguin group Eudyptes c. chrysocome/E. c. filholi.A study published in 2009 showed that the...

      , Eudyptes moseleyi
    • Royal Penguin
      Royal Penguin
      The Royal Penguin inhabits the waters surrounding Antarctica. Royals look very much like Macaroni Penguins, but have a white face and chin instead of the Macaronis' black visage. They are long and weigh . Males are larger than females...

      , Eudyptes schlegeli (disputed)
    • Macaroni Penguin
      Macaroni Penguin
      The Macaroni Penguin is a species of penguin found from the Subantarctic to the Antarctic Peninsula. One of six species of crested penguin, it is very closely related to the Royal Penguin, and some authorities consider the two to be a single species...

      , Eudyptes chrysolophus
    • Chatham Penguin, Eudyptes sp. (extinct)

Fossil genera


Order Sphenisciformes
  • Basal
    Basal (phylogenetics)
    In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...

     and unresolved taxa (all fossil
    Fossil
    Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

    )
    • Waimanu
      Waimanu
      Waimanu is a genus of early penguin which lived soon after the Cretaceous-Paleogene extinction event. Its discovery helped support the idea that the radiation of the Neoaves either took place before the extinction of the dinosaurs, or that it must have been extremely rapid in geological terms...

       – basal (Middle-Late Paleocene)
    • Perudyptes (Middle Eocene of Atacama Desert, Peru) – basal?
    • Spheniscidae gen. et sp. indet. CADIC P 21 (Leticia Middle Eocene of Punta Torcida, Argentina)
    • Delphinornis (Middle/Late Eocene? – Early Oligocene of Seymour Island, Antarctica) – Palaeeudyptinae, basal, new subfamily 1?
    • Archaeospheniscus
      Archaeospheniscus
      Archaeospheniscus is an extinct genus of large penguins. It currently contains three species, known from somewhat fragmentary remains. A...

       (Middle/Late Eocene – Late Oligocene) – Palaeeudyptinae? New subfamily 2?
    • Marambiornis (Late Eocene –? Early Oligocene of Seymour Island, Antarctica) – Palaeeudyptinae, basal, new subfamily 1?
    • Mesetaornis (Late Eocene –? Early Oligocene of Seymour Island, Antarctica) – Palaeeudyptinae, basal, new subfamily 1?
    • Tonniornis (Late Eocene –? Early Oligocene of Seymour Island, Antarctica)
    • Wimanornis (Late Eocene –? Early Oligocene of Seymour Island, Antarctica)
    • Duntroonornis (Late Oligocene of Otago, New Zealand) – possibly Spheniscinae
    • Korora (Late Oligocene of S Canterbury, New Zealand)
    • Platydyptes (Late Oligocene of New Zealand) – possibly not monophyletic; Palaeeudyptinae, Paraptenodytinae or new subfamily?
    • Spheniscidae gen. et sp. indet. (Late Oligocene/Early Miocene of Hakataramea, New Zealand)
    • Madrynornis (Puerto Madryn Late Miocene of Argentina) – possibly Spheniscinae
    • Pseudaptenodytes
      Pseudaptenodytes
      The extinct penguin genus Pseudaptenodytes contains the type species P. macraei; smaller bones have been assigned to P. minor, although it is not certain whether they are really from a different species or simply of younger individuals; both taxa are known by an insufficient selection of bones...

       (Late Miocene/Early Pliocene)
    • Dege (Early Pliocene of South Africa) – possibly Spheniscinae
    • Marplesornis (Early Pliocene) – possibly Spheniscinae
    • Nucleornis (Early Pliocene of Duinfontain, South Africa) – possibly Spheniscinae
    • Inguza (Late Pliocene) – probably Spheniscinae; formerly Spheniscus predemersus

  • Family Spheniscidae
    • Subfamily Palaeeudyptinae
      Palaeeudyptinae
      The New Zealand Giant Penguins, Palaeeudyptinae, are an extinct subfamily of penguins. It includes several genera of medium-sized to very large species - including Palaeeudyptes marplesi and Anthropornis nordenskjoeldi which grew tall or even larger, and the massive Pachydyptes ponderosus which...

       – Giant penguins (fossil
      Fossil
      Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

      )
      • Crossvallia (Cross Valley Late Paleocene of Seymour Island, Antarctica) – tentatively assigned to this subfamily
      • Anthropornis (Middle Eocene? – Early Oligocene of Seymour Island, Antarctica) – tentatively assigned to this subfamily
        • Nordenskjoeld's Giant Penguin, Anthropornis nordenskjoeldi
          Anthropornis nordenskjoeldi
          Anthropornis is a genus of giant penguin that lived 37-45 million years ago, during the Late Eocene and the earliest part of the Oligocene. It reached in height and in weight. Fossils of it have been found on Seymour Island off the coast of Antarctica and in New Zealand...

      • Icadyptes (Late Eocene of Atacama Desert, Peru)
      • Palaeeudyptes
        Palaeeudyptes
        Palaeeudyptes is an extinct genus of large penguins, currently containing four accepted species. They were probably larger than almost all living penguins, with the smaller species being about the size of an Emperor Penguin and the largest ones having stood about 1.5 meters tall.Of the four...

         (Middle/Late Eocene – Late Oligocene) – polyphyletic; some belong in other subfamilies
      • Pachydyptes
        Pachydyptes
        Pachydyptes is an extinct genus of penguin. It contains the single species Pachydyptes ponderosus, the New Zealand Giant Penguin...

         (Late Eocene)
      • Anthropodyptes
        Anthropodyptes
        -References:* Simpson, George Gaylord : A review of the pre-Pleistocene penguins of New Zealand. Bulletin of the American Museum of Natural History 144: 319–378....

         (Middle Miocene) – tentatively assigned to this subfamily
    • Subfamily Paraptenodytinae – Stout-footed penguins (fossil
      Fossil
      Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

      )
      • Arthrodytes (San Julian Late Eocene/Early Oligocene – Patagonia Early Miocene of Patagonia, Argentina)
      • Paraptenodytes
        Paraptenodytes
        Paraptenodytes is an extinct genus of penguins which contains two or three species sized between a Magellanic Penguin and an Emperor Penguin . They are known from fossil bones ranging from a partial skeleton and some additional material in the case of P. antarcticus, and a single humerus in the...

         (Early – Late Miocene/Early Pliocene)
    • Subfamily Palaeospheniscinae – Slender-footed penguins (fossil
      Fossil
      Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

      )
      • Eretiscus (Patagonia Early Miocene of Patagonia, Argentina)
      • Palaeospheniscus
        Palaeospheniscus
        Palaeospheniscus is an extinct genus of penguins which contains three species at present. They are all known from one or two handful of bones. All specimens were found in Santa Cruz and Chubut Provinces of Patagonia, Argentina...

         (Early? – Late Miocene/Early Pliocene) – includes Chubutodyptes


The Early Oligocene genus Cruschedula
Cruschedula
Cruschedula is an enigmatic bird genus considered to be nomen dubium which consists of the single species Cruschedula revola....

 was formerly thought to belong to Spheniscidae, however reexamination of the holotype in 1943 resulted in the genus being placed in Accipitridae
Accipitridae
The Accipitridae, one of the two major families within the order Accipitriformes , are a family of small to large birds with strongly hooked bills and variable morphology based on diet. They feed on a range of prey items from insects to medium-sized mammals, with a number feeding on carrion and a...

. Further examination in 1980 resulted in placement as Aves incertae sedis.

Taxonomy


Some recent sources apply the phylogenetic taxon  to what here is referred to as Spheniscinae. Furthermore, they restrict the phylogenetic taxon Sphenisciformes to flightless taxa, and establish the phylogenetic taxon as equivalent to the Linnean taxon Sphenisciformes, i.e., including any flying basal "proto-penguins" to be discovered eventually. Given that neither the relationships of the penguin subfamilies to each other nor the placement of the penguins in the avian phylogeny is presently resolved, this is confusing, so the established Linnean system is thus followed here.

Evolution


The evolution
Evolution
Evolution is any change across successive generations in the heritable characteristics of biological populations. Evolutionary processes give rise to diversity at every level of biological organisation, including species, individual organisms and molecules such as DNA and proteins.Life on Earth...

ary history of penguins is well-researched and represents a showcase of evolutionary biogeography
Biogeography
Biogeography is the study of the distribution of species , organisms, and ecosystems in space and through geological time. Organisms and biological communities vary in a highly regular fashion along geographic gradients of latitude, elevation, isolation and habitat area...

; though as penguin bones of any one species vary much in size and few good specimens are known, the alpha taxonomy
Alpha taxonomy
Alpha taxonomy is the discipline concerned with finding, describing and naming species of living or fossil organisms. This field is supported by institutions holding collections of these organisms, with relevant data, carefully curated: such institutes include natural history museums, herbaria and...

 of many prehistoric forms still leaves much to be desired. Some seminal articles about penguin prehistory have been published since 2005, the evolution of the living genera can be considered resolved by now.

The basal
Basal (phylogenetics)
In phylogenetics, a basal clade is the earliest clade to branch in a larger clade; it appears at the base of a cladogram.A basal group forms an outgroup to the rest of the clade, such as in the following example:...

 penguins lived around the time of the Cretaceous–Tertiary extinction event somewhere in the general area of (southern) New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

 and Byrd Land, Antarctica. Due to plate tectonics
Plate tectonics
Plate tectonics is a scientific theory that describes the large scale motions of Earth's lithosphere...

, these areas were at that time less than 1500 kilometres (932.1 mi) apart rather than the 4000 kilometres (2,485.5 mi) of today. The most recent common ancestor
Most recent common ancestor
In genetics, the most recent common ancestor of any set of organisms is the most recent individual from which all organisms in the group are directly descended...

 of penguins and their sister clade
Cladistics
Cladistics is a method of classifying species of organisms into groups called clades, which consist of an ancestor organism and all its descendants . For example, birds, dinosaurs, crocodiles, and all descendants of their most recent common ancestor form a clade...

 can be roughly dated to the Campanian
Campanian
The Campanian is, in the ICS' geologic timescale, the fifth of six ages of the Late Cretaceous epoch . The Campanian spans the time from 83.5 ± 0.7 Ma to 70.6 ± 0.6 Ma ...

Maastrichtian
Maastrichtian
The Maastrichtian is, in the ICS' geologic timescale, the latest age or upper stage of the Late Cretaceous epoch or Upper Cretaceous series, the Cretaceous period or system, and of the Mesozoic era or erathem. It spanned from 70.6 ± 0.6 Ma to 65.5 ± 0.3 Ma...

 boundary, around 70–68 mya.
What can be said as certainly as possible in the absence of direct (i.e., fossil) evidence is that by the end of the Cretaceous
Cretaceous
The Cretaceous , derived from the Latin "creta" , usually abbreviated K for its German translation Kreide , is a geologic period and system from circa to million years ago. In the geologic timescale, the Cretaceous follows the Jurassic period and is followed by the Paleogene period of the...

, the penguin lineage must have been evolutionarily well distinct, though much less so morphologically
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....

; it is fairly likely that they were not yet entirely flightless at that time, as flightless birds have generally low resilience to the breakdown of trophic webs that follows the initial phase of mass extinctions because of their below-average dispersal capabilities (see also Flightless Cormorant
Flightless Cormorant
The Flightless Cormorant , also known as the Galapagos Cormorant, is a cormorant native to the Galapagos Islands, and an example of the highly unusual fauna there. It is unique in that it is the only cormorant that has lost the ability to fly...

).

The basal fossils


The oldest known fossil
Fossil
Fossils are the preserved remains or traces of animals , plants, and other organisms from the remote past...

 penguin species is Waimanu manneringi, which lived in the early Paleocene
Paleocene
The Paleocene or Palaeocene, the "early recent", is a geologic epoch that lasted from about . It is the first epoch of the Palaeogene Period in the modern Cenozoic Era...

 epoch of New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

, or about 62 mya. While they were not as well-adapted to aquatic life as modern penguins, Waimanu
Waimanu
Waimanu is a genus of early penguin which lived soon after the Cretaceous-Paleogene extinction event. Its discovery helped support the idea that the radiation of the Neoaves either took place before the extinction of the dinosaurs, or that it must have been extremely rapid in geological terms...

 were generally loon
Loon
The loons or divers are a group of aquatic birds found in many parts of North America and northern Eurasia...

-like birds but already flightless, with short wings adapted for deep diving. They swam on the surface using mainly their feet, but the wings were – as opposed to most other diving birds, living and extinct – already adapting to underwater locomotion.

Perudyptes from northern Peru was dated to 42 mya. An unnamed fossil from Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...

 proves that by the Bartonian
Bartonian
The Bartonian is, in the ICS's geological timescale, a stage or age in the middle Eocene epoch or series. The Bartonian age spans the time between and . It is preceded by the Lutetian and is followed by the Priabonian age.-Stratigraphic definition:...

 (Middle Eocene
Eocene
The Eocene Epoch, lasting from about 56 to 34 million years ago , is a major division of the geologic timescale and the second epoch of the Paleogene Period in the Cenozoic Era. The Eocene spans the time from the end of the Palaeocene Epoch to the beginning of the Oligocene Epoch. The start of the...

), some 39–38 mya,
primitive penguins had spread to South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

 and were in the process of expanding into Atlantic waters.

Palaeeudyptines


During the Late Eocene and the Early Oligocene
Oligocene
The Oligocene is a geologic epoch of the Paleogene Period and extends from about 34 million to 23 million years before the present . As with other older geologic periods, the rock beds that define the period are well identified but the exact dates of the start and end of the period are slightly...

 (40–30 mya), some lineages of gigantic penguins existed. Nordenskjoeld's Giant Penguin was the tallest, growing nearly 1.80 meters (6 ft) tall. The New Zealand Giant Penguin was probably the heaviest, weighing 80 kg or more. Both were found on New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

, the former also in the Antarctic farther eastwards.

Traditionally, most extinct species of penguins, giant or small, had been placed in the paraphyletic subfamily called Palaeeudyptinae
Palaeeudyptinae
The New Zealand Giant Penguins, Palaeeudyptinae, are an extinct subfamily of penguins. It includes several genera of medium-sized to very large species - including Palaeeudyptes marplesi and Anthropornis nordenskjoeldi which grew tall or even larger, and the massive Pachydyptes ponderosus which...

. More recently, with new taxa being discovered and placed in the phylogeny if possible, it is becoming accepted that there were at least two major extinct lineages. One or two closely related ones occurred in Patagonia
Patagonia
Patagonia is a region located in Argentina and Chile, integrating the southernmost section of the Andes mountains to the southwest towards the Pacific ocean and from the east of the cordillera to the valleys it follows south through Colorado River towards Carmen de Patagones in the Atlantic Ocean...

, and at least one other—which is or includes the paleeudyptines as recognized today – occurred on most Antarctic
Antarctic
The Antarctic is the region around the Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica and the ice shelves, waters and island territories in the Southern Ocean situated south of the Antarctic Convergence...

 and subantarctic
Subantarctic
The Subantarctic is a region in the southern hemisphere, located immediately north of the Antarctic region. This translates roughly to a latitude of between 46° – 60° south of the Equator. The subantarctic region includes many islands in the southern parts of the Indian Ocean, Atlantic Ocean and...

 coasts.

But size plasticity seems to have been great at this initial stage of penguin radiation
Adaptive radiation
In evolutionary biology, adaptive radiation is the evolution of ecological and phenotypic diversity within a rapidly multiplying lineage. Starting with a recent single ancestor, this process results in the speciation and phenotypic adaptation of an array of species exhibiting different...

: on Seymour Island
Seymour Island
Seymour Island is an island in the chain of 16 major islands around the tip of the Graham Land on the Antarctic Peninsula. Graham Land is closer to continental land mass than any other part of that Antarctica. It lies within the section of the island chain that resides off the west side of the...

, Antarctica, for example, around 10 known species of penguins ranging in size from medium to huge apparently coexisted some 35 mya during the Priabonian
Priabonian
The Priabonian is, in the ICS's geologic timescale, the latest age or the upper stage of the Eocene epoch or series. It spans the time between and...

 (Late Eocene). It is not even known whether the gigantic palaeeudyptines constitute a monophyletic lineage, or whether gigantism was evolved independently in a much restricted Palaeeudyptinae and the Anthropornithinae – whether they were considered valid, or whether there was a wide size range present in the Palaeeudyptinae as delimited as usually done these days (i.e., including Anthropornis nordenskjoeldi
Anthropornis nordenskjoeldi
Anthropornis is a genus of giant penguin that lived 37-45 million years ago, during the Late Eocene and the earliest part of the Oligocene. It reached in height and in weight. Fossils of it have been found on Seymour Island off the coast of Antarctica and in New Zealand...

). The oldest well-described giant penguin, the 5 feet (1.5 m)-tall Icadyptes salasi
Icadyptes salasi
Icadyptes salasi was a giant penguin species from the late Eocene period, in the tropics of South America. "Ica" for the Peruvian region where it was found, "dyptes" from the Greek word for diver, and "salasi" for Rodolfo Salas, a noted Peruvian paleontologist.The fossilised remains of the penguin,...

, actually occurred as far north as northern Peru
Peru
Peru , officially the Republic of Peru , is a country in western South America. It is bordered on the north by Ecuador and Colombia, on the east by Brazil, on the southeast by Bolivia, on the south by Chile, and on the west by the Pacific Ocean....

 about 36 mya.

In any case, the gigantic penguins had disappeared by the end of the Paleogene
Paleogene
The Paleogene is a geologic period and system that began 65.5 ± 0.3 and ended 23.03 ± 0.05 million years ago and comprises the first part of the Cenozoic Era...

, around 25 mya. Their decline and disappearance coincided with the spread of the Squalodontoidea and other primitive, fish-eating toothed whale
Toothed whale
The toothed whales form a suborder of the cetaceans, including sperm whales, beaked whales, dolphins, and others. As the name suggests, the suborder is characterized by the presence of teeth rather than the baleen of other whales.-Anatomy:Toothed whales have a single blowhole on the top of the head...

s, which certainly competed with them for food, and were ultimately more successful. A new lineage, the Paraptenodytes
Paraptenodytes
Paraptenodytes is an extinct genus of penguins which contains two or three species sized between a Magellanic Penguin and an Emperor Penguin . They are known from fossil bones ranging from a partial skeleton and some additional material in the case of P. antarcticus, and a single humerus in the...

, which includes smaller but decidedly stout-legged forms, had already arisen in southernmost South America by that time. The early Neogene
Neogene
The Neogene is a geologic period and system in the International Commission on Stratigraphy Geologic Timescale starting 23.03 ± 0.05 million years ago and ending 2.588 million years ago...

 saw the emergence of yet another morphotype in the same area, the similarly sized but more gracile Palaeospheniscinae, as well as the radiation that gave rise to the penguin biodiversity
Biodiversity
Biodiversity is the degree of variation of life forms within a given ecosystem, biome, or an entire planet. Biodiversity is a measure of the health of ecosystems. Biodiversity is in part a function of climate. In terrestrial habitats, tropical regions are typically rich whereas polar regions...

 of our time.

Origin and systematics of modern penguins


Modern penguins consititute two undisputed clade
Clade
A clade is a group consisting of a species and all its descendants. In the terms of biological systematics, a clade is a single "branch" on the "tree of life". The idea that such a "natural group" of organisms should be grouped together and given a taxonomic name is central to biological...

s and another two more basal genera with more ambiguous relationships. The origin of the Spheniscinae lies probably in the latest Paleogene, and geographically it must have been much the same as the general area in which the order evolved: the oceans between the Australia-New Zealand region and the Antarctic. Presumedly diverging from other penguins around 40 mya, it seems that the Spheniscinae were for quite some time limited to their ancestral area, as the well-researched deposits of the Antarctic Peninsula
Antarctic Peninsula
The Antarctic Peninsula is the northernmost part of the mainland of Antarctica. It extends from a line between Cape Adams and a point on the mainland south of Eklund Islands....

 and Patagonia
Patagonia
Patagonia is a region located in Argentina and Chile, integrating the southernmost section of the Andes mountains to the southwest towards the Pacific ocean and from the east of the cordillera to the valleys it follows south through Colorado River towards Carmen de Patagones in the Atlantic Ocean...

 have not yielded Paleogene fossils of the subfamily. Also, the earliest spheniscine lineages are those with the most southern distribution.

The genus Aptenodytes
Aptenodytes
The genus Aptenodytes contains two extant species of penguins collectively known as "the great penguins".-Taxonomy:...

 appears to be the basalmost divergence among living penguins they have bright yellow-orange neck, breast, and bill patches; incubate by placing their eggs on their feet, and when they hatch the chicks are almost naked. This genus has a distribution centered on the Antarctic coasts and barely extends to some subantarctic islands today.

Pygoscelis
Pygoscelis
The genus Pygoscelis contains three living species of penguins collectively known as "The Brush-Tailed Penguins". Their appearance - black above, white below - is the stereotypical image of penguins, and so what most people think of when they think of penguins.-Taxonomy:Mitochondrial and nuclear...

 contains species with a fairly simple black-and-white head pattern; their distribution is intermediate, centered on Antarctic coasts but extending somewhat northwards from there. In external morphology
Morphology (biology)
In biology, morphology is a branch of bioscience dealing with the study of the form and structure of organisms and their specific structural features....

, these apparently still resemble the common ancestor of the Spheniscinae, as Aptenodytes autapomorphies are in most cases fairly pronounced adaptations related to that genus' extreme habitat
Habitat
* Habitat , a place where a species lives and grows*Human habitat, a place where humans live, work or play** Space habitat, a space station intended as a permanent settlement...

 conditions. As the former genus, Pygoscelis seems to have diverged during the Bartonian,
but the range expansion and radiation that led to the present-day diversity probably did not occur until much later; around the Burdigalian
Burdigalian
The Burdigalian is, in the geologic timescale, an age or stage in the early Miocene. It spans the time between 20.43 ± 0.05 Ma and 15.97 ± 0.05 Ma...

 stage of the Early Miocene
Miocene
The Miocene is a geological epoch of the Neogene Period and extends from about . The Miocene was named by Sir Charles Lyell. Its name comes from the Greek words and and means "less recent" because it has 18% fewer modern sea invertebrates than the Pliocene. The Miocene follows the Oligocene...

, roughly 20–15 mya.

The genera
Genus
In biology, a genus is a low-level taxonomic rank used in the biological classification of living and fossil organisms, which is an example of definition by genus and differentia...

 Spheniscus
Spheniscus
The banded penguins are the penguins of the Spheniscus genus. There are four living species of penguins known as banded penguins, and all have similar coloration. They are sometimes also known as "Jack-ass penguins" due to their loud locator calls sounding similar to a donkey braying...

 and Eudyptula
Eudyptula
The genus Eudyptula contains two species of penguin. It is found in southern Australia, Tasmania, New Zealand and the Chatham Islands....

 contain species with a mostly subantarctic distribution centered on South America
South America
South America is a continent situated in the Western Hemisphere, mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere. The continent is also considered a subcontinent of the Americas. It is bordered on the west by the Pacific Ocean and on the north and east...

; some, however, range quite far northwards. They all lack carotenoid
Carotenoid
Carotenoids are tetraterpenoid organic pigments that are naturally occurring in the chloroplasts and chromoplasts of plants and some other photosynthetic organisms like algae, some bacteria, and some types of fungus. Carotenoids can be synthesized fats and other basic organic metabolic building...

 coloration, and the former genus has a conspicuous banded head pattern; they are unique among living penguins by nesting in burrows. This group probably radiated eastwards with the Antarctic Circumpolar Current
Antarctic Circumpolar Current
The Antarctic Circumpolar Current is an ocean current that flows from west to east around Antarctica. An alternative name for the ACC is the West Wind Drift. The ACC is the dominant circulation feature of the Southern Ocean and, at approximately 125 Sverdrups, the largest ocean current...

 out of the ancestral range of modern penguins throughout the Chattian
Chattian
The Chattian is, in the geologic timescale, the youngest of two ages or upper of two stages of the Oligocene epoch/series. It spans the time between and . The Chattian is preceded by the Rupelian and is followed by the Aquitanian .-Stratigraphic definition:The Chattian was introduced by Austrian...

 (Late Oligocene), starting approximately 28 mya. While the two genera separated during this time, the present-day diversity is the result of a Pliocene
Pliocene
The Pliocene Epoch is the period in the geologic timescale that extends from 5.332 million to 2.588 million years before present. It is the second and youngest epoch of the Neogene Period in the Cenozoic Era. The Pliocene follows the Miocene Epoch and is followed by the Pleistocene Epoch...

 radiation, taking place some 4–2 mya.

The Megadyptes–Eudyptes clade occurs at similar latitude
Latitude
In geography, the latitude of a location on the Earth is the angular distance of that location south or north of the Equator. The latitude is an angle, and is usually measured in degrees . The equator has a latitude of 0°, the North pole has a latitude of 90° north , and the South pole has a...

s (though not as far north as the Galapagos Penguin
Galapagos Penguin
The Galapagos Penguin is a penguin endemic to the Galapagos Islands. It is the only penguin that lives north of the equator in the wild; it can survive due to the cool temperatures resulting from the Humboldt Current and cool waters from great depths brought up by the Cromwell Current...

), has its highest diversity in the New Zealand region, and represent a westward dispersal. They are characterized by hairy yellow ornamental head feathers; their bills are at least partly red. These two genera diverged apparently in the Middle Miocene (Langhian
Langhian
The Langhian is, in the ICS geologic timescale, an age or stage in the middle Miocene epoch/series. It spans the time between 15.97 ± 0.05 Ma and 13.65 ± 0.05 Ma . The Langhian was a continuing warming period defined by Lorenzo Pareto in 1864, it was originally established in the Langhe area north...

, roughly 15–14 mya), but again, the living species of Eudyptes are the product of a later radiation, stretching from about the late Tortonian
Tortonian
The Tortonian is in the geologic timescale an age or stage of the late Miocene that spans the time between 11.608 ± 0.005 Ma and 7.246 ± 0.005 Ma . It follows the Serravallian and is followed by the Messinian....

 (Late Miocene, 8 mya) to the end of the Pliocene.

The geographical and temporal pattern or spheniscine evolution corresponds closely to two episodes of global cooling
Global cooling
Global cooling was a conjecture during the 1970s of imminent cooling of the Earth's surface and atmosphere along with a posited commencement of glaciation...

 documented in the paleoclimatic record
Paleoclimatology
Paleoclimatology is the study of changes in climate taken on the scale of the entire history of Earth. It uses a variety of proxy methods from the Earth and life sciences to obtain data previously preserved within rocks, sediments, ice sheets, tree rings, corals, shells and microfossils; it then...

. The emergence of the subantarctic lineage at the end of the Bartonian corresponds with the onset of the slow period of cooling that eventually led to the ice age
Ice age
An ice age or, more precisely, glacial age, is a generic geological period of long-term reduction in the temperature of the Earth's surface and atmosphere, resulting in the presence or expansion of continental ice sheets, polar ice sheets and alpine glaciers...

s some 35 million years later. With habitat on the Antarctic coasts declining, by the Priabonian more hospitable conditions for most penguins existed in the subantarctic regions rather than in Antarctica itself. Notably, the cold Antarctic Circumpolar Current also started as a continuous circumpolar flow only around 30 mya, on the one hand forcing the Antarctic cooling, and on the other facilitating the eastward expansion of Spheniscus
Spheniscus
The banded penguins are the penguins of the Spheniscus genus. There are four living species of penguins known as banded penguins, and all have similar coloration. They are sometimes also known as "Jack-ass penguins" due to their loud locator calls sounding similar to a donkey braying...

 to South America and eventually beyond. Despite this, there is no fossil evidence to support the idea of a crown radiation from the antarctic continent in the Paleogene.

Later, an interspersed period of slight warming was ended by the Middle Miocene Climate Transition, a sharp drop in global average temperature from 14–12 mya, and similar abrupt cooling events followed at 8 mya and 4 mya; by the end of the Tortonian, the Antarctic ice sheet
Antarctic ice sheet
The Antarctic ice sheet is one of the two polar ice caps of the Earth. It covers about 98% of the Antarctic continent and is the largest single mass of ice on Earth. It covers an area of almost 14 million square km and contains 30 million cubic km of ice...

 was already much like today in volume and extent. The emergence of most of today's subantarctic penguin species almost certainly was caused by this sequence of Neogene climate shifts.

Relationship to other bird orders


Penguin ancestry beyond Waimanu
Waimanu
Waimanu is a genus of early penguin which lived soon after the Cretaceous-Paleogene extinction event. Its discovery helped support the idea that the radiation of the Neoaves either took place before the extinction of the dinosaurs, or that it must have been extremely rapid in geological terms...

 remains unknown and not well-resolved by molecular or morphological analyses. The latter tend to be confounded by the strong adaptive autapomorphies of the Sphenisciformes; a sometimes perceived fairly close relationship between penguins and grebe
Grebe
A grebe is a member of the Podicipediformes order, a widely distributed order of freshwater diving birds, some of which visit the sea when migrating and in winter...

s is almost certainly an error based on both groups' strong diving adaptations, which are homoplasies. On the other hand, different DNA sequence
DNA sequence
The sequence or primary structure of a nucleic acid is the composition of atoms that make up the nucleic acid and the chemical bonds that bond those atoms. Because nucleic acids, such as DNA and RNA, are unbranched polymers, this specification is equivalent to specifying the sequence of...

 datasets do not agree in detail with each other either.


What seems clear is that penguins belong to a clade of Neoaves (living birds except paleognaths and fowl
Fowl
Fowl is a word for birds in general but usually refers to birds belonging to one of two biological orders, namely the gamefowl or landfowl and the waterfowl...

) that comprises what is sometimes called "higher waterbirds" to distinguish them from the more ancient waterfowl
Waterfowl
Waterfowl are certain wildfowl of the order Anseriformes, especially members of the family Anatidae, which includes ducks, geese, and swans....

. This group contains such birds as stork
Stork
Storks are large, long-legged, long-necked wading birds with long, stout bills. They belong to the family Ciconiidae. They are the only family in the biological order Ciconiiformes, which was once much larger and held a number of families....

s, rail
Rallidae
The rails, or Rallidae, are a large cosmopolitan family of small to medium-sized birds. The family exhibits considerable diversity and the family also includes the crakes, coots, and gallinules...

s, and the seabird
Seabird
Seabirds are birds that have adapted to life within the marine environment. While seabirds vary greatly in lifestyle, behaviour and physiology, they often exhibit striking convergent evolution, as the same environmental problems and feeding niches have resulted in similar adaptations...

s, with the possible exception of the Charadriiformes
Charadriiformes
Charadriiformes is a diverse order of small to medium-large birds. It includes about 350 species and has members in all parts of the world. Most Charadriiformes live near water and eat invertebrates or other small animals; however, some are pelagic , some occupy deserts and a few are found in thick...

.

Inside this group, penguin relationships are far less clear. Depending on the analysis and dataset, a close relationship to Ciconiiformes
Ciconiiformes
Traditionally, the order Ciconiiformes has included a variety of large, long-legged wading birds with large bills: storks, herons, egrets, ibises, spoonbills, and several others. Ciconiiformes are known from the Late Eocene...

 or to Procellariiformes
Procellariiformes
Procellariiformes is an order of seabirds that comprises four families: the albatrosses, petrels and shearwaters, storm petrels, and diving petrels...

 has been suggested. Some think the penguin-like plotopterids
Plotopteridae
Plotopteridae is the name of an extinct family of flightless seabirds from the order Pelecaniformes. Related to the gannets and boobies, they exhibited remarkable convergent evolution with the penguins, particularly with the now extinct giant penguins...

 (usually considered relatives of anhinga
Anhinga
The Anhinga , sometimes called Snakebird, Darter, American Darter, or Water Turkey, is a water bird of the warmer parts of the Americas. The word "anhinga" comes from the Brazilian Tupi language and means devil bird or snake bird.It is a cormorant-like bird with an average body length of , a...

s and cormorant
Cormorant
The bird family Phalacrocoracidae is represented by some 40 species of cormorants and shags. Several different classifications of the family have been proposed recently, and the number of genera is disputed.- Names :...

s) may actually be a sister group of the penguins, and that penguins may have ultimately shared a common ancestor with the Pelecaniformes
Pelecaniformes
The Pelecaniformes is a order of medium-sized and large waterbirds found worldwide. As traditionally—but erroneously—defined, they encompass all birds that have feet with all four toes webbed. Hence, they were formerly also known by such names as totipalmates or steganopodes...

 and consequently would have to be included in that order, or that the plotopterids were not as close to other pelecaniforms as generally assumed, which would necessitate splitting the traditional Pelecaniformes in three.

Anatomy and physiology


Penguins are superbly adapted to aquatic
Aquatic ecosystem
An aquatic ecosystem is an ecosystem in a body of water. Communities of organisms that are dependent on each other and on their environment live in aquatic ecosystems. The two main types of aquatic ecosystems are marine ecosystems and freshwater ecosystems....

 life. Their vestigial wing
Wing
A wing is an appendage with a surface that produces lift for flight or propulsion through the atmosphere, or through another gaseous or liquid fluid...

s have become flippers, useless for flight in the air. In the water, however, penguins are astonishingly agile. Penguins' swimming looks very similar to bird's flight in the air. Within the smooth plumage
Plumage
Plumage refers both to the layer of feathers that cover a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage vary between species and subspecies and can also vary between different age classes, sexes, and season. Within species there can also be a...

 a layer of air is preserved, ensuring buoyancy. The air layer also helps insulate the birds in cold waters.
On land, penguins use their tail
Tail
The tail is the section at the rear end of an animal's body; in general, the term refers to a distinct, flexible appendage to the torso. It is the part of the body that corresponds roughly to the sacrum and coccyx in mammals, reptiles, and birds...

s and wings to maintain balance for their upright stance.

All penguins are countershaded
Countershading
Countershading, or Thayer's Law, is a form of camouflage. Countershading, in which an animal’s pigmentation is darker dorsally, is often thought to have an adaptive effect of reducing conspicuous shadows cast on the ventral region of an animal’s body...

 for camouflage
Camouflage
Camouflage is a method of concealment that allows an otherwise visible animal, military vehicle, or other object to remain unnoticed, by blending with its environment. Examples include a leopard's spotted coat, the battledress of a modern soldier and a leaf-mimic butterfly...

 – that is, they have black backs and wing
Wing
A wing is an appendage with a surface that produces lift for flight or propulsion through the atmosphere, or through another gaseous or liquid fluid...

s with white fronts. A predator looking up from below (such as an orca
Orca
The killer whale , commonly referred to as the orca, and less commonly as the blackfish, is a toothed whale belonging to the oceanic dolphin family. Killer whales are found in all oceans, from the frigid Arctic and Antarctic regions to tropical seas...

 or a leopard seal
Leopard Seal
The leopard seal , also referred to as the sea leopard, is the second largest species of seal in the Antarctic...

) has difficulty distinguishing between a white penguin belly and the reflective water surface. The dark plumage on their backs camouflages them from above.

Diving penguins reach 6 to 12 km/h (3.7 to 7.5 mph), though there are reports of velocities of 27 km/h (17 mph) (which are more realistic in the case of startled flight). The small penguins do not usually dive deep; they catch their prey near the surface in dives that normally last only one or two minutes. Larger penguins can dive deep in case of need. Dives of the large Emperor Penguin have been recorded reaching a depth of 565 m (1,870 ft) for up to 22 minutes.

Penguins either waddle on their feet or slide on their bellies across the snow, a movement called "tobogganing", which conserves energy while moving quickly. They also jump with both feet together if they want to move more quickly or cross steep or rocky terrain.

Penguins have an average sense of hearing
Hearing (sense)
Hearing is the ability to perceive sound by detecting vibrations through an organ such as the ear. It is one of the traditional five senses...

 for birds; this is used by parents and chicks to locate one another in crowded colonies. Their eyes are adapted for underwater vision, and are their primary means of locating prey and avoiding predators; in air it has been suggested that they are nearsighted, although research has not supported this hypothesis.

Penguins have a thick layer of insulating feathers that keeps them warm in water (heat loss in water is much greater than in air). The Emperor Penguin (the largest penguin) has the largest body mass of all penguins, which further reduces relative surface area and heat loss. They also are able to control blood flow to their extremities, reducing the amount of blood that gets cold, but still keeping the extremities from freezing. In the extreme cold of the Antarctic winter, the females are at sea fishing for food leaving the males to brave the weather by themselves. They often huddle together to keep warm and rotate positions to make sure that each penguin gets a turn in the center of the heat pack.

They can drink salt water because their supraorbital gland
Supraorbital gland
The supraorbital gland is a type of lateral nasal gland found in some species of marine birds, particularly penguins, which removes sodium chloride from the bloodstream. The gland's function is similar to that of the kidneys, though it is much more efficient at removing salt, allowing Penguins to...

 filters excess salt from the bloodstream. The salt is excreted in a concentrated fluid from the nasal passages.

The Auk
Auk
An auk is a bird of the family Alcidae in the order Charadriiformes. Auks are superficially similar to penguins due to their black-and-white colours, their upright posture and some of their habits...

 of the Northern Hemisphere
Northern Hemisphere
The Northern Hemisphere is the half of a planet that is north of its equator—the word hemisphere literally means “half sphere”. It is also that half of the celestial sphere north of the celestial equator...

 is superficially similar to penguins. They are not related to the penguins at all, but considered by some to be a product of moderate convergent evolution
Convergent evolution
Convergent evolution describes the acquisition of the same biological trait in unrelated lineages.The wing is a classic example of convergent evolution in action. Although their last common ancestor did not have wings, both birds and bats do, and are capable of powered flight. The wings are...

.

Isabelline penguins



Perhaps one in 50,000 penguins (of most species) are born with brown rather than black plumage. These are called isabelline
Isabelline (colour)
Isabelline , sometimes called Isabella, is a colour, variously described as pale grey-yellow, pale fawn, pale cream-brown or parchment....

 penguins, possibly in reference to the legend that the archduchess Isabella of Austria
Infanta Isabella Clara Eugenia of Spain
Isabella Clara Eugenia of Austria was sovereign of the Spanish Netherlands in the Low Countries and the north of modern France, together with her husband Albert. In some sources, she is referred to as Clara Isabella Eugenia...

 vowed not to change her undergarments until her husband's siege of Ostend
Ostend
Ostend  is a Belgian city and municipality located in the Flemish province of West Flanders. It comprises the boroughs of Mariakerke , Stene and Zandvoorde, and the city of Ostend proper – the largest on the Belgian coast....

 was successful—which took over three years to accomplish. Isabellinism is different from albinism. Isabelline penguins tend to live shorter lives than normal penguins, as they are not well-camouflaged against the deep, and are often passed over as mates.

Distribution and habitat


Although all penguin species are native to the southern hemisphere, they are not found only in cold climates, such as Antarctica. In fact, only a few species of penguin actually live so far south. At least 10 species live in the temperate
Temperate
In geography, temperate or tepid latitudes of the globe lie between the tropics and the polar circles. The changes in these regions between summer and winter are generally relatively moderate, rather than extreme hot or cold...

 zone; one, the Galápagos Penguin
Galapagos Penguin
The Galapagos Penguin is a penguin endemic to the Galapagos Islands. It is the only penguin that lives north of the equator in the wild; it can survive due to the cool temperatures resulting from the Humboldt Current and cool waters from great depths brought up by the Cromwell Current...

, lives as far north as the Galápagos Islands
Galápagos Islands
The Galápagos Islands are an archipelago of volcanic islands distributed around the equator in the Pacific Ocean, west of continental Ecuador, of which they are a part.The Galápagos Islands and its surrounding waters form an Ecuadorian province, a national park, and a...

, but this is only made possible by the cold, rich waters of the Antarctic Humboldt Current
Humboldt Current
The Humboldt Current , also known as the Peru Current, is a cold, low-salinity ocean current that flows north-westward along the west coast of South America from the southern tip of Chile to northern Peru. It is an eastern boundary current flowing in the direction of the equator, and can extend...

 that flows around these islands.

Several authors have suggested that penguins are a good example of Bergmann's Rule
Bergmann's Rule
Bergmann's rule is an ecogeographic principle that states that within a broadly distributed genus, species of larger size are found in colder environments, and species of smaller size are found in warmer regions. Although originally formulated in terms of species within a genus, it has often been...

  where larger bodied populations live at higher latitudes than smaller bodied populations. There is some disagreement about this, and several other authors have noted that there are fossil penguin species that contradict this hypothesis and that ocean currents and upwellings are likely to have had a greater effect on species diversity than latitude alone.

Major populations of penguins are found in:
Antarctica, Argentina
Argentina
Argentina , officially the Argentine Republic , is the second largest country in South America by land area, after Brazil. It is constituted as a federation of 23 provinces and an autonomous city, Buenos Aires...

, Australia
Australia
Australia , officially the Commonwealth of Australia, is a country in the Southern Hemisphere comprising the mainland of the Australian continent, the island of Tasmania, and numerous smaller islands in the Indian and Pacific Oceans. It is the world's sixth-largest country by total area...

, Chile
Chile
Chile ,officially the Republic of Chile , is a country in South America occupying a long, narrow coastal strip between the Andes mountains to the east and the Pacific Ocean to the west. It borders Peru to the north, Bolivia to the northeast, Argentina to the east, and the Drake Passage in the far...

, New Zealand
New Zealand
New Zealand is an island country in the south-western Pacific Ocean comprising two main landmasses and numerous smaller islands. The country is situated some east of Australia across the Tasman Sea, and roughly south of the Pacific island nations of New Caledonia, Fiji, and Tonga...

, and South Africa
South Africa
The Republic of South Africa is a country in southern Africa. Located at the southern tip of Africa, it is divided into nine provinces, with of coastline on the Atlantic and Indian oceans...

.

Behaviour



Breeding


Penguins for the most part breed in large colonies, the exceptions being the Yellow-eyed and Fiordland species; these colonies may range in size from as few as a 100 pairs for Gentoo Penguins, to several hundred thousand in the case of King, Macaroni and Chinstrap Penguins. Living in colonies results in a high level of social interaction between birds, which has led to a large repertoire of visual as well as vocal displays in all penguin species. Agonistic displays are those intended to confront or drive off, or alternately appease and avoid conflict with, other individuals.

Penguins form monogamous pairs for a breeding season, though the rate the same pair recouples varies drastically. Most penguins lay two eggs in a clutch, although the two largest species, the Emperor and the King Penguin
King Penguin
The King Penguin is the second largest species of penguin at about , second only to the Emperor Penguin. There are two subspecies—A. p. patagonicus and A. p...

s, lay only one. With the exception of the Emperor Penguin, where the male does it all, all penguins share the incubation
Avian incubation
Incubation refers to the process by which certain oviparous animals hatch their eggs, and to the development of the embryo within the egg. The most vital factor of incubation is the constant temperature required for its development over a specific period. Especially in domestic fowl, the act of...

 duties. These incubation shifts can last days and even weeks as one member of the pair feeds at sea.

Penguins generally only lay one brood; the exception is the Little Penguin, which can raise two or three broods in a season.

Penguin eggs are smaller than any other bird species when compared proportionally to the weight of the parent birds; at 52 g (2 oz), the Little Penguin egg is 4.7% of its mothers' weight, and the 450 g (0.992080179831949 lb) Emperor Penguin egg is 2.3%. The relatively thick shell forms between 10 and 16 % of the weight of a penguin egg, presumably to minimise risk of breakage in an adverse nesting environment. The yolk, too, is large, and comprises 22–31 % of the egg. Some yolk often remains when a chick is born, and is thought to help sustain it if parents are delayed in returning with food.

When mothers lose a chick, they sometimes attempt to "steal" another mother's chick, usually unsuccessfully as other females in the vicinity assist the defending mother in keeping her chick. In some species, such as Emperor Penguin
Emperor Penguin
The Emperor Penguin is the tallest and heaviest of all living penguin species and is endemic to Antarctica. The male and female are similar in plumage and size, reaching in height and weighing anywhere from . The dorsal side and head are black and sharply delineated from the white belly,...

s, young penguins assemble in large groups called crèche
Crèche (zoology)
The Crèche in zoology refers to care of another's offspring, for instance in a colony. This term is used in the study of bird colonies...

s.

Penguins and humans



Penguins seem to have no special fear of humans, and have approached groups of explorers without hesitation. This is probably because penguins have no land predators in Antarctica or the nearby offshore islands. Instead, penguins are at risk at sea from predators such as the leopard seal
Leopard Seal
The leopard seal , also referred to as the sea leopard, is the second largest species of seal in the Antarctic...

. Typically, penguins do not approach closer than about 3 meters (10 ft) at which point they become nervous. This is also the distance that Antarctic tourists are told to keep from penguins (tourists are not supposed to approach closer than 3 meters, but are not expected to withdraw if the penguins come closer).

In popular culture




Penguins are popular around the world, primarily for their unusually upright, waddling gait and (compared to other birds) lack of fear of humans. Their striking black-and-white plumage is often likened to a tuxedo
Black tie
Black tie is a dress code for evening events and social functions. For a man, the main component is a usually black jacket, known as a dinner jacket or tuxedo...

 suit. Mistakenly, some artists and writers have penguins based at the North Pole
North Pole
The North Pole, also known as the Geographic North Pole or Terrestrial North Pole, is, subject to the caveats explained below, defined as the point in the northern hemisphere where the Earth's axis of rotation meets its surface...

. This is incorrect, as there are almost no wild penguins in the northern hemisphere
Northern Hemisphere
The Northern Hemisphere is the half of a planet that is north of its equator—the word hemisphere literally means “half sphere”. It is also that half of the celestial sphere north of the celestial equator...

, except the small group on the northernmost of the Galápagos. The cartoon series Chilly Willy
Chilly Willy
Chilly Willy is a cartoon character, a diminutive anthropomorphic penguin living in Alaska, although the species is native only to the southern hemisphere. He was created by Paul J. Smith for the Walter Lantz studio in 1953...

 helped perpetuate this myth, as the title penguin would interact with northern-hemisphere species such as polar bears and walruses.

Penguins have been the subject of many books and films such as Happy Feet
Happy Feet
Happy Feet is a 2006 American-Australian computer-animated family film with music, directed and co-written by George Miller. It was produced at Sydney-based visual effects and animation studio Animal Logic for Warner Bros., Village Roadshow Pictures and Kingdom Feature Productions and was released...

, Surf's Up
Surf's Up (film)
Surf's Up is a 2007 American computer-animated mockumentary family comedy film directed by Ash Brannon and Chris Buck. It stars the voices of Shia LaBeouf, Jeff Bridges, Zooey Deschanel and Jon Heder among others....

 and The Penguins of Madagascar
The Penguins of Madagascar
The Penguins of Madagascar is an American CGI animated television series airing on Nickelodeon. It stars nine characters from the DreamWorks Animation animated film Madagascar: The penguins Skipper , Kowalski , Private , and Rico ; the lemurs King Julien , Maurice , and Mort...

, all CGI
Computer-generated imagery
Computer-generated imagery is the application of the field of computer graphics or, more specifically, 3D computer graphics to special effects in art, video games, films, television programs, commercials, simulators and simulation generally, and printed media...

 films; March of the Penguins
March of the Penguins
March of the Penguins is a 2005 French nature documentary film. It was directed and co-written by Luc Jacquet, and co-produced by Bonne Pioche and the National Geographic Society. The film depicts the yearly journey of the emperor penguins of Antarctica...

, a documentary based on the migration
Bird migration
Bird migration is the regular seasonal journey undertaken by many species of birds. Bird movements include those made in response to changes in food availability, habitat or weather. Sometimes, journeys are not termed "true migration" because they are irregular or in only one direction...

 process of the Emperor Penguin
Emperor Penguin
The Emperor Penguin is the tallest and heaviest of all living penguin species and is endemic to Antarctica. The male and female are similar in plumage and size, reaching in height and weighing anywhere from . The dorsal side and head are black and sharply delineated from the white belly,...

; and a parody titled Farce of the Penguins
Farce of the Penguins
Farce of the Penguins is a 2007 American direct-to-video parody of the 2005 documentary March of the Penguins. The motion picture features Samuel L. Jackson as narrator, with the two main characters being voiced by Bob Saget, who also wrote and directed the film, and Lewis Black...

. Mr. Popper's Penguins
Mr. Popper's Penguins
Mr. Popper's Penguins is a children's book written by Richard and Florence Atwater, originally published in 1938. It tells the story of a poor house painter named Mr. Popper and his family, who live in the small town of Stillwater in the 1930s...

 is a children's book written by Richard & Florence Atwater; it was named a Newbery Honor Book in 1939. Penguins have also found their way into a number of cartoons and television dramas; perhaps the most notable of these is Pingu
Pingu
Pingu is a British-Swiss stop-motion claymated television series created by Otmar Gutmann. The series was produced by The Pygos Group and Trickfilmstudio for Swiss television. The show is about a family of anthropomorphic penguins at the South Pole. The main character is the family's son and title...

, created by Silvio Mazzola in 1986 and covering more than 100 short episodes. Entertainment Weekly
Entertainment Weekly
Entertainment Weekly is an American magazine, published by the Time division of Time Warner, that covers film, television, music, broadway theatre, books and popular culture...

 put it on its end-of-the-decade, "best-of" list, saying, "Whether they were walking (March of the Penguins), dancing (Happy Feet), or hanging ten (Surf's Up), these oddly adorable birds took flight at the box office all decade long."

The tendency of penguins to form large groups feeds the stereotype that they all look exactly alike, a popular notion exploited by cartoonists such as Gary Larson
Gary Larson
Gary Larson is the creator of The Far Side, a single-panel cartoon series that was syndicated internationally to newspapers for 15 years. The series ended with Larson's retirement on January 1, 1995. His 23 books of collected cartoons have combined sales of more than 45 million...

.

Penguins featured regularly in the cartoons of UK cartoonist Steve Bell
Steve Bell (cartoonist)
Steve Bell is an English political cartoonist, whose work appears in The Guardian and other publications. He is known for his left-wing views and distinctive caricatures.-Early life:...

 in his strip in The Guardian
The Guardian
The Guardian, formerly known as The Manchester Guardian , is a British national daily newspaper in the Berliner format...

 Newspaper, particularly during and following the Falklands War
Falklands War
The Falklands War , also called the Falklands Conflict or Falklands Crisis, was fought in 1982 between Argentina and the United Kingdom over the disputed Falkland Islands and South Georgia and the South Sandwich Islands...

.

In the mid-2000s, penguins became one of the most publicized species of animals that form lasting homosexual couples. A children's book
Children's literature
Children's literature is for readers and listeners up to about age twelve; it is often defined in four different ways: books written by children, books written for children, books chosen by children, or books chosen for children. It is often illustrated. The term is used in senses which sometimes...

, And Tango Makes Three
And Tango Makes Three
And Tango Makes Three is a 2005 children's book written by Peter Parnell and Justin Richardson and illustrated by Henry Cole. The book is based on the true story of Roy and Silo, two male Chinstrap Penguins in New York's Central Park Zoo...

, was written about one such penguin family
Roy and Silo
Roy and Silo are Chinstrap Penguins who were a male-male pair in New York City's Central Park Zoo.Roy and Silo met at the zoo and they began their relationship in 2004. The pair were observed trying to hatch a rock as if it were an egg. They also attempted to steal eggs from other penguin couples...

 in the New York Zoo
Central Park Zoo
The Central Park Zoo is a small zoo located in Central Park in New York City. It is part of an integrated system of four zoos and the New York Aquarium managed by the Wildlife Conservation Society , and is accredited by the Association of Zoos and Aquariums .The zoo began in the 1860s as a...

.

External links