Penguin

Penguins (order Sphenisciformes, family Spheniscidae) are a group of aquatic, flightless birds living almost exclusively in the southern hemisphere, especially in Antarctica. Highly adapted for life in the water, penguins have countershaded dark and white plumage, and their wings have become flippers. Most penguins feed on krill, fish, squid, 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 zone, and one species, the Galápagos Penguin, lives near the equator.

The largest living species is the Emperor Penguin (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 (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). Some prehistoric species attained enormous sizes, becoming as tall or as heavy as an adult human (see below for more). These were not restricted to Antarctic regions; on the contrary, subantarctic regions harboured high diversity, and at least one giant penguin occurred in a region not quite 2,000 km south of the equator 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, nor of Breton or Spanish origin (both attributed to the French word pingouin "auk"), but first appears in English or Dutch. the American Heritage Dictionary, the Century Dictionary and Merriam-Webster, on the basis that the name was originally applied to the great auk, 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. the actual situation seems to be more complicated. Similarly, it is still unclear whether the Royal Penguin is merely a color morph of the Macaroni penguin. The status of the Rockhopper penguins is also unclear.

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

Subfamily Spheniscinae – Modern penguins

Aptenodytes – Great penguins

* King Penguin, Aptenodytes patagonicus

* Emperor Penguin, Aptenodytes forsteri

Pygoscelis – Brush-tailed penguins

* Adélie Penguin, Pygoscelis adeliae

* Chinstrap Penguin, Pygoscelis antarctica

* Gentoo Penguin, Pygoscelis papua

Eudyptula – Little penguins

* Little Blue Penguin, Eudyptula minor

* White-flippered Penguin, Eudyptula albosignata (provisional)

Spheniscus – Banded penguins

* Magellanic Penguin, Spheniscus magellanicus

* Humboldt Penguin, Spheniscus humboldti

* Galapagos Penguin, Spheniscus mendiculus

* African Penguin, Spheniscus demersus

Megadyptes

* Yellow-eyed Penguin, Megadyptes antipodes

* Waitaha Penguin, Megadyptes waitaha (extinct)

Eudyptes – Crested penguins

* Fiordland Penguin, Eudyptes pachyrynchus

* Snares Penguin, Eudyptes robustus

* Erect-crested Penguin, Eudyptes sclateri

* Western Rockhopper Penguin, Eudyptes chrysocome

* Eastern Rockhopper Penguin, Eudyptes filholi

* Northern Rockhopper Penguin, Eudyptes moseleyi

* Royal Penguin, Eudyptes schlegeli (disputed)

* Macaroni Penguin, Eudyptes chrysolophus

* Chatham Islands Penguin, Eudyptes sp. (extinct)

Fossil genera

Order Sphenisciformes

Basal and unresolved taxa (all fossil)

* Waimanu – 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 (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 (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

of the prehistoric Narrow-flippered Penguin (Palaeeudyptes antarcticus).]]

Family Spheniscidae

* Subfamily Palaeeudyptinae – Giant penguins (fossil)

** 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

** Icadyptes (Late Eocene of Atacama Desert, Peru)

** Palaeeudyptes (Middle/Late Eocene – Late Oligocene) – polyphyletic; some belong in other subfamilies

** Pachydyptes (Late Eocene)

** Anthropodyptes (Middle Miocene) – tentatively assigned to this subfamily

Subfamily Paraptenodytinae – Stout-footed penguins (fossil)

* Arthrodytes (San Julian Late Eocene/Early Oligocene – Patagonia Early Miocene of Patagonia, Argentina)

** Paraptenodytes (Early – Late Miocene/Early Pliocene)

* Subfamily Palaeospheniscinae – Slender-footed penguins (fossil)

* Eretiscus (Patagonia Early Miocene of Patagonia, Argentina)

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

The Early Oligocene genus Cruschedula was formerly thought to belong to Spheniscidae, however reexamination of the holotype in 1943 resulted in the genus being placed in Accipitridae. 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 evolutionary history of penguins is well-researched and represents a showcase of evolutionary biogeography; though as penguin bones of any one species vary much in size and few good specimens are known, the alpha taxonomy 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 penguins lived around the time of the Cretaceous–Tertiary extinction event somewhere in the general area of (southern) New Zealand and Byrd Land, Antarctica. 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, the penguin lineage must have been evolutionarily well distinct, though much less so morphologically; 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).

The basal fossils

The oldest known fossil penguin species is Waimanu manneringi, which lived in the early Paleocene epoch of New Zealand, or about 62 mya. primitive penguins had spread to South America and were in the process of expanding into Atlantic waters. 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). 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 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, 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 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 stage of the Early Miocene, roughly 20–15 mya. 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 to South America and eventually beyond.

Inside this group, penguin relationships are far less clear. Depending on the analysis and dataset, a close relationship to Ciconiiformes

Anatomy and physiology

s swim by an iceberg with Adelie Penguins in the Ross Sea, Antarctica. The Drygalski ice tongue is visible in the background.|thumb|250px]]

Penguins are superbly adapted to aquatic life. Their vestigial wings 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 a layer of air is preserved, ensuring buoyancy. The air layer also helps insulate the birds in cold waters. On land, penguins use their tails and wings to maintain balance for their upright stance.

All penguins are countershaded for camouflage – that is, they have black backs and wings with white fronts. A predator looking up from below (such as an orca or a leopard seal) 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 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. swimming underwater at Nagasaki Penguin Aquarium.]] 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 filters excess salt from the bloodstream. The salt is excreted in a concentrated fluid from the nasal passages.

The Auk of the Northern Hemisphere 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.

Isabelline penguins

Adélie Penguin on Gourdin Island.]] Perhaps one in 50,000 penguins (of most species) are born with brown rather than black plumage. These are called isabelline penguins, possibly in reference to the legend that the archduchess Isabella of Austria vowed not to change her undergarments until her husband united the northern and southern Low Countries by taking the city of Ostend—which took 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 zone; one, the Galápagos Penguin, lives as far north as the Galápagos Islands, but this is only made possible by the cold, rich waters of the Antarctic Humboldt Current that flows around these islands.

Several authors have suggested that penguins are a good example of Bergmann's Rule 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, Australia, New Zealand, South America, and South Africa.

Behaviour

s in Antarctica.]]

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. With the exception of the Emperor Penguin, all penguins share the incubation 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 , the Little Penguin egg is 4.7% of its mothers' weight, and the Emperor Penguin egg is 2.3%.

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 Penguins, young penguins assemble in large groups called crèches.

Penguins and humans

preparing a penguin for consumption]] 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. 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

during Antarctic summer.]] the Linux kernel mascot.]]

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 suit. Mistakenly, some artists and writers have penguins based at the North Pole. This is incorrect, as there are almost no wild penguins in the northern hemisphere, except the small group on the northernmost of the Galápagos. The cartoon series Chilly Willy 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 and Surf's Up, both CGI films; March of the Penguins, a documentary based on the migration process of the Emperor Penguin; and a parody titled Farce of the Penguins. Mr. Popper's Penguins 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, created by Silvio Mazzola in 1986 and covering more than 100 short episodes. Entertainment Weekly 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.

Penguins featured regularly in the cartoons of UK cartoonist Steve Bell in his strip in The Guardian Newspaper, particularly during and following the Falklands War.

In the mid-2000s, penguins became one of the most publicized species of animals that form lasting homosexual couples. A children's book, And Tango Makes Three, was written about one such penguin family in the New York Zoo.

References

Footnotes

Bibliography

Two new fossil penguin species found in Peru

Acosta Hospitaleche, Carolina (2004): Los pingüinos (Aves, Sphenisciformes) fósiles de Patagonia. Sistemática, biogeografía y evolución. Doctoral thesis, Department of Natural Sciences and Museum, Universidad Nacional de La Plata. La Plata, Argentina. PDF fulltext Baker, Allan J.; Pereira, Sergio Luiz; Haddrath, Oliver P. & Edge, Kerri-Anne (2006): Multiple gene evidence for expansion of extant penguins out of Antarctica due to global cooling. Proc. R. Soc. B 273: 11-17. PDF fulltext

Banks, Jonathan C.; Mitchell, Anthony D.; Waas, Joseph R. & Paterson, Adrian M. (2002): An unexpected pattern of molecular divergence within the blue penguin (Eudyptula minor) complex. Notornis 49(1): 29–38. PDF fulltext

Bertelli, Sara & Giannini, Norberto P. (2005): A phylogeny of extant penguins (Aves: Sphenisciformes) combining morphology and mitochondrial sequences. Cladistics 21(3): 209–239. (HTML abstract)

Clarke, Julia A.; Olivero, Eduardo B. & Puerta, Pablo (2003): Description of the earliest fossil penguin from South America and first Paleogene vertebrate locality of Tierra Del Fuego, Argentina. American Museum novitates 3423: 1-18. PDF fulltext

Davis; Lloyd S. & Renner; M. (1995). Penguins . London: T & A D Poyser. ISBN 0-7136-6550-5

Fain, Matthew G. & Houde, Peter (2004): Parallel radiations in the primary clades of birds. Evolution 58(11): 2558-2573. PDF fulltext

Jadwiszczak, Piotr (2006): Eocene penguins of Seymour Island, Antarctica: taxonomy. Polish Polar Research 27(1), 3–62. PDF fulltext

Jouventin, P; Aubin, T. & T Lengagne (1999) "Finding a parent in a king penguin colony: the acoustic system of individual recognition" Animal Behaviour 57: 1175–1183

Ksepka, Daniel T., Bertelli, Sara & Giannini, Norberto P. (2006): The phylogeny of the living and fossil Sphenisciformes (penguins). Cladistics 22(5): 412–441. (HTML abstract)

Marples, B. J. (1962): Observations on the history of penguins. In: Leeper, G. W. (ed.), The evolution of living organisms. Melbourne, Melbourne University Press: 408-416.

Mayr, G. (2005): Tertiary plotopterids (Aves, Plotopteridae) and a novel hypothesis on the phylogenetic relationships of penguins (Spheniscidae). Journal of Zoological Systematics and Evolutionary Research 43(1): 61-71. PDF fulltext

Sivak, J.; Howland, H. & McGill-Harelstad, P. (1987) "Vision of the Humboldt Penguin (Spheniscus humboldti) in Air and Water" Proceedings of the Royal Society of London. Series B, Biological Sciences. 229(1257): 467-472

Slack, Kerryn E.; Jones, Craig M.; Ando, Tatsuro; Harrison G. L. "Abby"; Fordyce R. Ewan; Arnason, Ulfur & Penny, David (2006): Early Penguin Fossils, plus Mitochondrial Genomes, Calibrate Avian Evolution. Molecular Biology and Evolution 23(6): 1144-1155. PDF fulltext Supplementary Material

Wever, E.; Herman, P.; Simmons, J. & Hertzler D (1969) "Hearing in the Blackfooted Penguin, Spheniscus demersus, as Represented by the Cochlear Potentials" PNAS 63(3): 676-680

Williams; Tony D. (1995). The Penguins - Spheniscidae . Oxford: Oxford University Press. ISBN 0-19-854667-X

External links

Information about penguins at pinguins.info

Integrated Taxonomic Information System

Penguin information on 70South

Penguin research projects on the web

Penguin videos and photos on the Internet Bird Collection

Penguin World

Penguins in Te Ara the Encyclopedia of New Zealand

Seaworld Penguin Information

National Wildlife Magazine 1/15/2010">"Lessons in a Land of Wind and Ice" from National Wildlife Magazine 1/15/2010

Category:Antarctic birds Category:Articles containing video clips Category:Flightless birds Category:Seabirds