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Penguins Temporal range: Paleocene-Recent
Gentoo Penguin, Pygoscelis papua
Scientific classification
Kingdom:	Animalia
Phylum:	Chordata
Class:	Aves
Order:	Sphenisciformes Sharpe, 1891
Family:	Spheniscidae Bonaparte, 1831
Modern genera
Aptenodytes Eudyptes Eudyptula Megadyptes Pygoscelis Spheniscus For prehistoric genera, see Systematics

Penguins (order Sphenisciformes, family Spheniscidae) are a group of aquatic, flightless birds living almost exclusively in the Southern Hemisphere.

The number of penguin species is debated. Depending on which authority is followed, penguin biodiversity varies between 17 and 20 living species, all in the subfamily Spheniscinae. Some sources consider the White-flippered Penguin a separate Eudyptula species, while others treat it as a subspecies of the Little Penguin (e.g. Williams, 1995; Davis & Renner, 2003); the actual situation seems to be more complicated (Banks et al. 2002). Similarly, it is still unclear whether the Royal Penguin is merely a color morph of the Macaroni penguin. Also eligible to be a separate species is the Northern population of Rockhopper penguins (Davis & Renner, 2003). Although all penguin species are native to the southern hemisphere, they are not, contrary to popular belief, found only in cold climates, such as Antarctica. In fact, only a few species of penguin actually live so far south. At least ten species live in the temperate zone; one lives as far north as the Galápagos Islands: the Galápagos Penguin.

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 (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 2000 km south of the Equator 35 mya, in a climate decidedy warmer than today.

Most penguins feed on krill, fish, squid, and other forms of sealife caught while swimming underwater. They spend half of their life on land and half in the oceans.

Penguins seem to have no special fear of humans and have approached groups of explorers without hesitation. This is probably on account of there being no land predators in Antarctica or the nearby offshore islands that prey on or attack penguins. Instead, penguins are at risk at sea from predators such as the leopard seal. Typically, penguins do not approach closer than about 3 meters (9 ft); they become nervous at about that distance. 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).

Penguins Are now an official extinct species in the wild. The only ones left are the ones in the zoos. This is all on your shoulders you people that drive big SUVs, and need a new can of hairspray every other hour.

                       The late Save The Penguin Society

Systematics and evolution

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 (Bertelli & Giannini 2005, Baker et al. 2006, Ksepka et al. 2006, Slack et al. 2006), the evolution of the living genera can be considered resolved by now.

According to the comprehensive review of the available evidence by Ksepka et al. (2006), 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. Due to plate tectonics, these areas were at that time less than Template:Km to mi apart rather than the Template:Km to mi of today. The most recent common ancestor of penguins and their sister clade can be roughly dated to the Campanian-Maastrichtian boundary, around 70-68 mya (Baker et al. 2006, Slack et al. 2006) 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 which follows the initial phase of mass extinctions because of their below-average dispersal capabilities (see also Flightless Cormorant).

Palaeëudyptines

During the Late Eocene and the Early Oligocene (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, 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. More recently, with new taxa being discovered and placed in the phylogeny if possible, it is becoming accepted that there were at least 2 major extinct lineages. One or two closely related ones occurred in Patagonia, and at least one other - which is or includes the paleeeudyptines as recognized today - occurred on most Antarctic and subantarctic coasts.

But size plasticity seems to have been great at this initial stage of penguin radiation: on Seymour Island, Antarctica, for example, around ten known species of penguins ranging from medium to huge size apparently coexisted some 35 mya during the Priabonian (Late Eocene) (Jadwiszczak 2006). 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 - were they 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) (Ksepka et al. 2006). The oldest well-described giant penguin, the 5-foot-tall Icadyptes salasi, actually occurred as far north as northern Peru about 36 mya.

In any case, the gigantic penguins had disappeared by the end of the Paleogene, around 25 mya. Interestingly, their decline and disappearance coincides with the spread of the Squalodontoidea and other primitive, fish-eating toothed whales, which certainly competed with them for food, and were ultimately more successful (Baker et al. 2006). A new lineage, the Paraptenodytes which includes smaller but decidedly stout-legged forms, had already arisen in southernmost South America by that time. The early Neogene saw the emergence of yet another morphotype in the same area, the similarly-sized but more gracile Palaeospheniscinae, as well as the radiation which gave rise to the penguin biodiversity of our time.

Origin and systematics of modern penguins

Modern penguins consititute two undisputed clades and another two more basal genera with more ambiguous relationships (Bertelli & Giannini 2005). 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 (Baker et al. 2006). Presumedly diverging from other penguins around 40 mya (Baker et al. 2006), it seems that the Spheniscinae were for quite some time limited to their ancestral area, as the well-researched deposits of the Antarctic Peninsula and Patagonia have not yielded Paleogene fossils of the subfamily. Also, the earliest spheniscine lineages are those with the most southern distribution.

The genus Aptenodytes 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, they 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 which lead to the present-day diversity probably did not occur until much later, around the Burdigalian stage of the Early Miocene, roughly 20-15 mya (Baker et al. 2006).

The genera Spheniscus and Eudyptula contain species with a mostly subantarctic distribution centered on South America; some, however, range quite far northwards. They all lack carotenoid coloration, and the former genus has a conspicuous banded head pattern; they are unique among living penguins in nesting in burrows. This group probably radiated eastwards with the Antarctic Circumpolar Current out of the ancestral range of modern penguins throughout the Chattian (Late Oligocene), starting approximately 28 mya (Baker et al. 2006). While the two genera separated during this time, the present-day diversity is the result of a Pliocene radiation, taking place some 4-2 mya (Baker et al. 2006).

The Megadyptes - Eudyptes clade occurs at similar latitudes (though not as far north as the Galapagos Penguin), 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, roughly 15-14 mya), but again, the living species of Eudyptes are the product of a later radiation, stretching from about the late Tortonian (Late Miocene, 8 mya) to the end of the Pliocene (Baker et al. 2006).

It is most interesting to note that the geographical and temporal pattern or spheniscine evolution corresponds closely to two episodes of global cooling documented in the paleoclimatic record (Baker et al. 2006). 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 ages 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 to South America and eventually beyond (Baker et al. 2006).

Later, an interspersed period of slight warming was ended by the Middle Miocene Climate Transition, a sharp drop in global average temperature from 14 to 12 mya, and similar abrupt cooling events followed at 8 mya and 4 mya; by the end of the Tortonian, the Antarctic ice sheet 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 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 grebes is almost certainly an error based on both groups' strong diving adaptations, which are homoplasies. On the other hand, different DNA sequence 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) which comprises what is sometimes called "higher waterbirds" to distinguish them from the more ancient waterfowl. This group contains such birds as storks, rails, and the seabirds, with the possible exception of the Charadriiformes (Fain & Houde 2004).

Inside this group, penguin relationships are far less clear. Depending on the analysis and dataset, a close relationship to Ciconiiformes (e.g. Slack et al. 2006) or to Procellariiformes (Baker et al. 2006) has been suggested. Some (e.g. Mayr 2005) think the penguin-like plotopterids (usually considered relatives of anhingas and cormorants) may actually be a sister group of the penguins, and that penguins may have ultimately shared a common ancestor with the Pelecaniformes 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.

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

Penguins and humans

Penguins in popular culture

Penguins are popular around the world, primarily for their unusually upright, waddling pace and (compared to other birds) lack of fear of humans. Their striking black and white plumage is often likened to a tuxedo suit. Perhaps in reaction to this cutesy stereotype, fictional penguins are occasionally presented as grouchy or even sinister. Penguins have also been the subject of many books and documentary films such as Happy Feet and Surf's Up, both CGI-Animated Animal Adventure Films, March of the Penguins, a documentary based on the migration process of Emperors, and a parody film entitled Farce of the Penguins. Mistakenly, some artists and writers have penguins based in the North Pole. This is incorrect as there are almost no wild penguins in the northern hemisphere, and those only barely (northernmost of the Galápagos). 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.

Gallery of living species

• Emperor Penguins
  Aptenodytes forsteri
• King Penguins
  Aptenodytes patagonicus
• Chinstrap Penguin
  Pygoscelis antarctica
• Gentoo Penguin
  Pygoscelis papua
• Royal Penguin
  Eudyptes schlegeli
• Southern Rockhopper Penguin
  Eudyptes chrysocome
• Fiordland Penguin
  Eudyptes pachyrhynchus
• Snares Penguin
  Eudyptes robustus
• Macaroni Penguin
  Eudyptes chrysolophus
• Yellow-eyed Penguin
  Megadyptes antipodes
• Little Penguin or Fairy Penguin
  Eudyptula minor
• African Penguin or Jackass Penguin Spheniscus demersus African Penguin or Jackass Penguin
  Spheniscus demersus
• Galapagos Penguins
  Spheniscus mendiculus
• Humboldt Penguin
  Spheniscus humboldti
• Magellanic Penguin
  Spheniscus magellanicus
• Adélie penguins
  Pygoscelis adeliae at iceberg in Ross Sea, Antarctica
• Emperor Penguins Aptenodytes forsteri (a parent with a chick) Emperor Penguins
  Aptenodytes forsteri (a parent with a chick)
• Emperor Penguins
  Aptenodytes forsteri (a parent with a chick and lonely chick behind)
• Emperor Penguins
  Aptenodytes forsteri - a chick
• Macaroni penguin at South Georgia Island
• Chinstrap Penguin feeding a chick in Antarctica
• Adélie chicks in Antarctica
• Southern Elephant Seal and King Penguins

References

• 2 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. doi:10.1098/rspb.2005.3260 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. doi:10.1111/j.1096-0031.2005.00065.x (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. doi:10.1554/04-235 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. doi:10.1111/j.1096-0031.2006.00116.x (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. doi:10.1111/j.1439-0469.2004.00291.x 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. doi:10.1093/molbev/msj124 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

Footnotes

1. The exact divergence dates according to Baker et al. (2006) mentioned in this section are not as precisely resolved as it appears to be due to uncertainties of the molecular clock used.
2. In fact, it is fairly likely that during the Bartonian, there was a near-synchronous but allopatric split between the ancestors of Aptenodytes, Pygoscelis, and the common ancestor of all remaining genera (Baker et al. 2006).
3. Convergence and divergence in the evolution of aquatic birds by Marcel Van Tuinen, Dave Brian Butvill, John A. W. Kirsch and S. Blair Hedges

External links

• Penguin World
• penguinpage.net - Penguin research projects on the web
• Penguin information on 70South
• Information about penguins at pinguins.info
• PBS Nature: The World of Penguins
• Integrated Taxonomic Information System
• Seaworld Penguin Information
• Penguin Videos on the Internet Bird Collection

Template:Link FA Template:Link FA

• Misplaced Pages articles needing factual verification from May 2007
• Antarctic birds
• Flightless birds
• Penguins
• Seabirds
• Bird families
• Spheniscidae
• Spheniscinae
• Sphenisciformes