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Penguins (
order Order, ORDER or Orders may refer to: * Categorization, the process in which ideas and objects are recognized, differentiated, and understood * Heterarchy, a system of organization wherein the elements have the potential to be ranked a number of d ...
Sphenisciformes Penguins ( order Sphenisciformes , family Spheniscidae ) are a group of aquatic flightless birds. They live almost exclusively in the Southern Hemisphere: only one species, the Galápagos penguin, is found north of the Equator. Highly adapt ...
,
family Family (from la, familia) is a Social group, group of people related either by consanguinity (by recognized birth) or Affinity (law), affinity (by marriage or other relationship). The purpose of the family is to maintain the well-being of its ...
Spheniscidae ) are a group of aquatic
flightless bird Flightless birds are birds that through evolution lost the ability to fly. There are over 60 extant species, including the well known ratites (ostriches, emu, cassowaries, rheas, and kiwi) and penguins. The smallest flightless bird is the In ...
s. They live almost exclusively in the Southern Hemisphere: only one
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
, the
Galápagos penguin The Galápagos penguin (''Spheniscus mendiculus'') is a penguin endemic to the Galápagos Islands, Ecuador. It is the only penguin found north of the equator. Most inhabit Fernandina Island and the west coast of Isabela Island. The cool waters ...
, is found north of the
Equator The equator is a circle of latitude, about in circumference, that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the North and South poles. The term can als ...
. Highly adapted for life in the water, penguins have
countershaded Countershading, or Thayer's law, is a method of camouflage in which an animal's coloration is darker on the top or upper side and lighter on the underside of the body. This pattern is found in many species of mammals, reptiles, birds, fish, and ...
dark and white
plumage Plumage ( "feather") is a layer of feathers that covers a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage differ between species and subspecies and may vary with age classes. Within species, ...
and flippers for swimming. Most penguins feed on
krill Krill are small crustaceans of the order Euphausiacea, and are found in all the world's oceans. The name "krill" comes from the Norwegian Norwegian, Norwayan, or Norsk may refer to: *Something of, from, or related to Norway, a country in n ...
,
fish Fish are aquatic, craniate, gill-bearing 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. Approximately 95% of li ...
,
squid True squid are molluscs with an elongated soft body, large eyes, eight arms, and two tentacles in the superorder Decapodiformes, though many other molluscs within the broader Neocoleoidea are also called squid despite not strictly fitting t ...
and other forms of
sea life Sea Life is a chain of commercial sea life-themed aquarium attractions. there are 53 Sea Life attractions (including standalone Sea Life centres, mini Sea Life features within resort theme parks, and Legoland submarine rides) around the world ...
which they catch with their bills and swallow it whole while swimming. A penguin has a spiny tongue and powerful jaws to grip slippery prey. They spend roughly half of their lives on land and the other half in the sea. The largest living species is the
emperor penguin The emperor penguin (''Aptenodytes forsteri'') 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 length and weighing from . Feathers of th ...
(''Aptenodytes forsteri''): on average, adults are about tall and weigh . The smallest penguin species is the
little blue penguin The little penguin (''Eudyptula minor'') is a species of penguin from New Zealand. They are commonly known as little blue penguins or blue penguins owing to their slate-blue plumage and are also known by their Māori name . The Australian lit ...
(''Eudyptula minor''), also known as the fairy penguin, which stands around tall and weighs . Today, larger penguins generally inhabit colder regions, and smaller penguins inhabit regions with temperate or
tropical climate Tropical climate is the first of the five major climate groups in the Köppen climate classification identified with the letter A. Tropical climates are defined by a monthly average temperature of 18 °C (64.4 °F) or higher in the cool ...
s. Some
prehistoric Prehistory, also known as pre-literary history, is the period of human history between the use of the first stone tools by hominins 3.3 million years ago and the beginning of recorded history with the invention of writing systems. The use of ...
penguin species were enormous: as tall or heavy as an adult human. There was a great diversity of species in
subantarctic The sub-Antarctic zone is a region in the Southern Hemisphere, located immediately north of the Antarctic region. This translates roughly to a latitude of between 46° and 60° south of the Equator. The subantarctic region includes many islands ...
regions, and at least one giant species in a region around 2,000 km south of the
equator The equator is a circle of latitude, about in circumference, that divides Earth into the Northern and Southern hemispheres. It is an imaginary line located at 0 degrees latitude, halfway between the North and South poles. The term can als ...
35 
mya Mya may refer to: Brands and product names * Mya (program), an intelligent personal assistant created by Motorola * Mya (TV channel), an Italian Television channel * Midwest Young Artists, a comprehensive youth music program Codes * Burmese ...
, during the Late
Eocene The Eocene ( ) Epoch is a geological epoch (geology), epoch that lasted from about 56 to 33.9 million years ago (mya). It is the second epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), Era. The name ''Eocene' ...
, a climate decidedly warmer than today.


Etymology

The word ''penguin'' first appears in literature at the end of the 16th century. When European explorers discovered what are today known as penguins in the Southern Hemisphere, they noticed their similar appearance to the
great auk The great auk (''Pinguinus impennis'') is a species of flightless alcid that became extinct in the mid-19th century. It was the only modern species in the genus ''Pinguinus''. It is not closely related to the birds now known as penguins, wh ...
of the
Northern Hemisphere The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's Nort ...
, and named them after this bird, although they are not closely related. The etymology of the word ''penguin'' is still debated. The English word is not apparently of
French French (french: français(e), link=no) may refer to: * Something of, from, or related to France ** French language, which originated in France, and its various dialects and accents ** French people, a nation and ethnic group identified with Franc ...
,
Breton Breton most often refers to: *anything associated with Brittany, and generally ** Breton people ** Breton language, a Southwestern Brittonic Celtic language of the Indo-European language family, spoken in Brittany ** Breton (horse), a breed **Ga ...
or
Spanish Spanish might refer to: * Items from or related to Spain: **Spaniards are a nation and ethnic group indigenous to Spain **Spanish language, spoken in Spain and many Latin American countries **Spanish cuisine Other places * Spanish, Ontario, Cana ...
pingüino
. Diccionario de la lengua española. rae.es
origin (the latter two are attributed to the French word ), but first appears in English or Dutch. Some dictionaries suggest a derivation from
Welsh Welsh may refer to: Related to Wales * Welsh, referring or related to Wales * Welsh language, a Brittonic Celtic language spoken in Wales * Welsh people People * Welsh (surname) * Sometimes used as a synonym for the ancient Britons (Celtic peop ...
, "head" and , "white", including the ''
Oxford English Dictionary The ''Oxford English Dictionary'' (''OED'') is the first and foundational historical dictionary of the English language, published by Oxford University Press (OUP). It traces the historical development of the English language, providing a com ...
'', the ''
American Heritage Dictionary American(s) may refer to: * American, something of, from, or related to the United States of America, commonly known as the "United States" or "America" ** Americans, citizens and nationals of the United States of America ** American ancestry, pe ...
'', the ''
Century Dictionary ''The Century Dictionary and Cyclopedia'' is one of the largest encyclopedic dictionaries of the English language. In its day it was compared favorably with the ''Oxford English Dictionary,'' and frequently consulted for more factual informati ...
'' and ''
Merriam-Webster Merriam-Webster, Inc. is an American company that publishes reference books and is especially known for its dictionaries. It is the oldest dictionary publisher in the United States. In 1831, George and Charles Merriam founded the company as ...
'', on the basis that the name was originally applied to the great auk, either because it was found on
White Head Island White Head Island is an island located in the Bay of Fundy. It is off the east coast of Grand Manan Island, New Brunswick. In 2011 the island had a population of 162. White Head Island is governed as a local service district. Its economy is bas ...
( cy, Pen Gwyn) in Newfoundland, or because it had white circles around its eyes (though the head was black). An alternative etymology links the word to
Latin Latin (, or , ) is a classical language belonging to the Italic branch of the Indo-European languages. Latin was originally a dialect spoken in the lower Tiber area (then known as Latium) around present-day Rome, but through the power of the ...
, which means "fat" or "oil". Support for this etymology can be found in the alternative Germanic word for penguin, or "fat-goose", and the related Dutch word . Adult male penguins are called ''cocks'', females are ''hens''; a group of penguins on land is a ''waddle'', and a group of penguins in the water is a ''raft''.


Pinguinus

Since 1871, the Latin word ''Pinguinus'' has been used in
scientific classification Taxonomy is the practice and science of categorization or classification. A taxonomy (or taxonomical classification) is a scheme of classification, especially a hierarchical classification, in which things are organized into groups or types. ...
to name the genus of the
great auk The great auk (''Pinguinus impennis'') is a species of flightless alcid that became extinct in the mid-19th century. It was the only modern species in the genus ''Pinguinus''. It is not closely related to the birds now known as penguins, wh ...
(''Pinguinus impennis'', meaning "penguin without
flight feather Flight feathers (''Pennae volatus'') are the long, stiff, asymmetrically shaped, but symmetrically paired pennaceous feathers on the wings or tail of a bird; those on the wings are called remiges (), singular remex (), while those on the tail ...
s"), which became
extinct Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and ...
in the mid-19th century. As confirmed by a 2004 genetic study, the genus ''Pinguinus'' belongs in the family of the
auk An auk or alcid is a bird of the family Alcidae in the order Charadriiformes. The alcid family includes the murres, guillemots, auklets, puffins, and murrelets. The word "auk" is derived from Icelandic ''álka'', from Old Norse ''alka'' (a ...
s (Alcidae), within the order of the
Charadriiformes Charadriiformes (, from ''Charadrius'', the type genus of family Charadriidae) is a diverse order of small to medium-large birds. It includes about 390 species and has members in all parts of the world. Most charadriiform birds live near water an ...
. The birds currently known as penguins were discovered later and were so named by sailors because of their physical resemblance to the great auk. Despite this resemblance, however, they are not auks, and are not closely related to the great auk. They do not belong in the genus ''Pinguinus'', and are not classified in the same family and order as the great auk. They were classified in 1831 by Charles Bonaparte in several distinct genera within the family
Spheniscidae Penguins ( order Sphenisciformes , family Spheniscidae ) are a group of aquatic flightless birds. They live almost exclusively in the Southern Hemisphere: only one species, the Galápagos penguin, is found north of the Equator. Highly adapt ...
and order
Sphenisciformes Penguins ( order Sphenisciformes , family Spheniscidae ) are a group of aquatic flightless birds. They live almost exclusively in the Southern Hemisphere: only one species, the Galápagos penguin, is found north of the Equator. Highly adapt ...
.


Systematics and evolution


Living and recently extinct species

The number of extinct penguin
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
is debated. Depending on which authority is followed, penguin
biodiversity Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic (''genetic variability''), species (''species diversity''), and ecosystem (''ecosystem diversity'') l ...
varies between 17 and 20 living species, all in the
subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...
Spheniscinae. Some sources consider the
white-flippered penguin The little penguin (''Eudyptula minor'') is a species of penguin from New Zealand. They are commonly known as little blue penguins or blue penguins owing to their slate-blue plumage and are also known by their Māori name . The Australian lit ...
a separate ''
Eudyptula The genus ''Eudyptula'' ("good little diver") contains two species of penguin, found in southern Australia, Tasmania, and New Zealand (including the Chatham Islands). They are commonly known as the little penguin, little blue penguin, or, in Aus ...
'' species, while others treat it as a subspecies of the
little blue penguin The little penguin (''Eudyptula minor'') is a species of penguin from New Zealand. They are commonly known as little blue penguins or blue penguins owing to their slate-blue plumage and are also known by their Māori name . The Australian lit ...
; WilliamsDavis; Lloyd S. & Renner; M. (1995). ''
Penguins Penguins ( order Sphenisciformes , family Spheniscidae ) are a group of aquatic flightless birds. They live almost exclusively in the Southern Hemisphere: only one species, the Galápagos penguin, is found north of the Equator. Highly adapt ...
''. London: T & A D Poyser.
the actual situation seems to be more complicated. Similarly, it is still unclear whether the
royal penguin The royal penguin (''Eudyptes schlegeli'') is a species of penguin, which can be found on the sub-Antarctic Macquarie Island and adjacent islands. The International Union for Conservation of Nature (IUCN) classifies the royal penguin as near th ...
is a separate species or merely a color morph of the
macaroni penguin The macaroni penguin (''Eudyptes chrysolophus'') 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 conside ...
. The status of the
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 three species. Not all experts agree on the classification of these penguins. Some c ...
s is also unclear. Updated after Marples (1962), Acosta Hospitaleche (2004), and Ksepka ''et al.'' (2006). Subfamily Spheniscinae – modern penguins


Fossil genera

Order Sphenisciformes * Basal and unresolved taxa (all
fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
) ** ''
Anthropodyptes ''Anthropodyptes'' is a poorly known monotypic genus of extinct penguin. It contains the single species ''Anthropodyptes gilli'', known from a Middle Miocene humerus from Australia. The bone is somewhat similar to those found in members of the N ...
'' (Middle Miocene) ** ''
Arthrodytes ''Arthrodytes'' is an extinct genus of penguins which contains a single species, whose remains have been recovered from the San Julian Formation (Late Eocene to Early Oligocene) of Patagonia. Other authors report a younger age for the fossils re ...
'' (San Julian Late Eocene/Early Oligocene – Patagonia Early Miocene of Patagonia, Argentina) ** '' Aprosdokitos'' Hospitaleche, Reguero & Santillana 2017 ** ''
Crossvallia ''Crossvallia'' is an extinct genus of penguins. It includes two species, ''C. unienwillia'' and ''?C. waiparensis''. Their anatomy suggests that the genus is closely related to the Anthropornithinae. Taxonomy Order Sphenisciformes * Family S ...
'' (Cross Valley Late Paleocene of Seymour Island, Antarctica) ** '' Ichthyopteryx'' Wiman 1905 ** ''
Kupoupou ''Kupoupou'' (meaning "diving bird" in Moriori dialect, Ta Rē Moriori) is an extinct genus of bird from the Paleocene-aged Takatika Grit of the Chatham Islands, New Zealand which is believed to be the oldest penguin genus known to date. The type ...
'' (Late Early-Middle Paleocene of Takatika Grit, New Zealand) ** ''
Kaiika ''Kaiika'' (Māori for "eater of fish") is an extinct genus of basal penguin from Early Eocene ( Waipawan-Mangaorapan subage) deposits of South Canterbury, New Zealand. It is known only from a single humerus. It was found in 1998 by Dr Philli ...
'' Fordyce & Tomas 2011 (Maxwell's penguin) ** ''
Korora ''Korora oliveri'', also referred to as Oliver's penguin, is a genus and species of extinct penguin from the Waitakian Stage (Late Oligocene to Early Miocene) of New Zealand. It was relatively small and slender, similar in size to one of the l ...
'' (Late Oligocene of S Canterbury, New Zealand) ** ''
Inguza ''Inguza predemersus'' is an extinct species of penguin. It was formerly placed in the genus ''Spheniscus'' and presumed to be a close relative of the African penguin, but after its well-distinct tarsometatarsus was found, it was moved into its p ...
'' (Late Pliocene) ** ''
Muriwaimanu ''Muriwaimanu'' is an extinct genus of early penguin. One species is known, ''Muriwaimanu tuatahi'', which was originally referred to ''Waimanu tuatahi'' in 2006 by Slack ''et al.''.Slack, K.E., Jones, C.M., Ando, T., Harrison G.L., Fordyce R.E. ...
'' (Late Paleocene of Canterbury, New Zealand) ** '' Nucleornis'' (Early Pliocene of Duinfontain, South Africa) ** '' Orthopteryx'' Wiman 1905 ** ''
Palaeoapterodytes ''Palaeoapterodytes ictus'' is an extinct species of penguin from the late Oligocene or early Miocene of Argentina, the only member of its genus. Its fossil remains, consisting of only of a severely worn proximal part of a humerus, were found i ...
'' (Late Oligocene/Early Miocene of Argentina) ** ''
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 individual ...
'' (Late Miocene/Early Pliocene) ** ''
Sequiwaimanu ''Sequiwaimanu'' is an extinct genus of early penguin. The type species, ''Sequiwaimanu rosieae'', was named and described by Gerald Mayr in 2018. It is the fourth penguin species to be discovered from the Waipara Greensand in New Zealand, which ...
'' (Late Paleocene) ** '' Tasidyptes'' Van Tets & O'Connor 1983 nomen dubium (Hunter Island penguins) ** ''
Tereingaornis ''Tereingaornis moisleyi'', also referred to as Moisley's penguin, is a genus and species of extinct penguin from the Middle Pliocene of New Zealand. It was slightly smaller than the extant Fiordland crested penguin. It was described by Ron Sca ...
'' (Middle Pliocene of New Zealand) ** '' Tonniornis'' (Late Eocene –? Early Oligocene of Seymour Island, Antarctica) ** '' Wimanornis'' (Late Eocene –? Early Oligocene of Seymour Island, Antarctica) * Spheniscidae ** ''
Waimanu ''Waimanu'' is a genus of early penguin which lived during the Paleocene, soon after the Cretaceous–Paleogene extinction event, around 62–60 million years ago. It was about the size of an emperor penguin (1 metre). It is one of the most impor ...
'' Jones, Ando & Fordyce 2006 (Middle-Late Paleocene) ** ''
Kumimanu ''Kumimanu'' is an extinct genus of giant penguin, which lived around 60 to 56 million years ago. The type and only species is ''K. biceae'', which arose after the Cretaceous–Paleogene extinction event, extinction of the non-avian dinosaurs. F ...
'' Mayr, 2017 ** ''
Delphinornis ''Delphinornis'' is an extinct genus of penguins that lived around the middle Eocene to the middle Miocene in Antarctica Antarctica () is Earth's southernmost and least-populated continent. Situated almost entirely south of the Antarcti ...
'' Wiman 1905 (Middle/Late Eocene? – Early Oligocene of Seymour Island, Antarctica) ** '' Marambiornis'' Myrcha et al. 2002 (Late Eocene –? Early Oligocene of Seymour Island, Antarctica) ** '' Mesetaornis'' Myrcha et al. 2002 (Late Eocene –? Early Oligocene of Seymour Island, Antarctica) ** ''
Perudyptes ''Perudyptes'' is a basal (phylogenetics), basal penguin from the Eocene, Middle Eocene Paracas Formation of Peru.Anthropornis ''Anthropornis'' is a genus of giant penguin that lived 45-33 million years ago, during the Late Eocene and the earliest part of the Oligocene.Myrcha, A., Jadwiszczak, P., Tambussi, C.P., Noriega, J.I., Gazdzicki, A., Tatur, A., and Valle, R.A. ...
'' Wiman 1905 (Middle Eocene? – Early Oligocene of Seymour Island, Antarctica) ** ''
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 s ...
'' Huxley 1859 (Middle/Late Eocene – Late Oligocene) ** ''
Icadyptes ''Icadyptes'' is an extinct genus of giant penguins from the Late Eocene tropics of South America. Etymology The genus name is a combination of "''Ica''" for the Peruvian region where the type species was found and "dyptes" from the Greek ...
'' Clarke et al. 2007 (Late Eocene of Atacama Desert, Peru) ** ''
Pachydyptes ''Pachydyptes'' is an extinct genus of penguin. It contains the single species ''Pachydyptes ponderosus'', the New Zealand giant penguin. This taxon is known from a few bones from Late Eocene (37 to 34 MYA) rocks in the area of Otago, which we ...
'' Oliver 1930 (Late Eocene) ** ''
Inkayacu ''Inkayacu'' is a genus of extinct penguins. It lived in what is now Peru during the Late Eocene, around 36 million years ago. A nearly complete skeleton was discovered in 2008 and includes fossilized feathers, the first known in penguins. A stud ...
'' Clarke et al. 2010 (Late Eocene of South America) ** ''
Kairuku ''Kairuku'' is an extinct genus of penguin. It contains three species, ''K. grebneffi'', ''K. waitaki'' and ''K. waewaeroa''. This taxon is known from bones from 27 MYA (late Oligocene), from the Kokoamu Greensand Formation of New Zealand. ...
'' Ksepka et al. 2012 (Late Oligocene of E South Island, New Zealand) ** ''
Paraptenodytes ''Paraptenodytes'' is an extinct genus of penguins which contains two or three species sized between a Magellanic penguin and an emperor penguin (''Aptenodytes forsteri''). They are known from fossil bones ranging from a partial skeleton and some ...
'' Ameghino 1891 (Early – Late Miocene/Early Pliocene) ** ''
Archaeospheniscus ''Archaeospheniscus'' is an extinct genus of large penguins. It currently contains three species, known from somewhat fragmentary remains. ''A. wimani'', the smallest species (about the size of a gentoo penguin), was found in Middle or Late Eocen ...
'' Marples 1952 (Middle/Late Eocene – Late Oligocene) ** ''
Duntroonornis ''Duntroonornis parvus'', also referred to as the Duntroon penguin, is a genus and species of extinct penguin from the Late Oligocene of New Zealand. The penguin was relatively small, similar in size to the Fiordland crested penguin. It was des ...
'' Marples 1953 (Late Oligocene of Otago, New Zealand) ** ''
Platydyptes ''Platydyptes'' is a genus of extinction, extinct penguins from the Late Oligocene to Early Miocene (about 27.3 to 21.7 million years ago) of New Zealand. It was created by Brian Marples in 1952 and contains three relatively large species, all o ...
'' Marples 1952 (Late Oligocene of New Zealand) ** '' Dege'' Simpson 1979 (Early Pliocene of South Africa) – possibly Spheniscinae ** ''
Marplesornis ''Marplesornis novaezealandiae'', also referred to as Harris's penguin is a genus and species of extinct penguin from New Zealand. It was a relatively large penguin, about the same size as a king penguin. The age of the only known specimen is ...
'' Simpson 1972 (Early Pliocene) ** Subfamily
Palaeospheniscinae ''Palaeospheniscus'' is an extinct genus of penguins belonging to the subfamily Palaeospheniscinae. These penguins are apparently not closely related to the modern genus ''Spheniscus''. Description The species of ''Palaeospheniscus'' were medium ...
(slender-footed penguins) (
fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
) *** '' Eretiscus'' Olson 1986 (Patagonia Early Miocene of Patagonia, Argentina) *** ''
Palaeospheniscus ''Palaeospheniscus'' is an extinct genus of penguins belonging to the subfamily Palaeospheniscinae. These penguins are apparently not closely related to the modern genus ''Spheniscus''. Description The species of ''Palaeospheniscus'' were medium ...
'' Moreno & Mercerat 1891 (Early? – Late Miocene/Early Pliocene) – includes ''Chubutodyptes'' ** Subfamily
Spheniscinae Penguins ( order Sphenisciformes , family Spheniscidae ) are a group of aquatic flightless birds. They live almost exclusively in the Southern Hemisphere: only one species, the Galápagos penguin, is found north of the Equator. Highly adapt ...
*** Spheniscidae gen. et sp. indet. CADIC P 21 (Leticia Middle Eocene of Punta Torcida, Argentina) *** Spheniscidae gen. et sp. indet. (Late Oligocene/Early Miocene of Hakataramea, New Zealand) *** '' Madrynornis'' (Puerto Madryn Late Miocene of Argentina) The
Early Oligocene The Rupelian is, in the geologic timescale, the older of two ages or the lower of two stages of the Oligocene Epoch/Series. It spans the time between . It is preceded by the Priabonian Stage (part of the Eocene) and is followed by the Chatti ...
genus ''
Cruschedula ''Cruschedula'' is an enigmatic bird genus considered to be ''nomen dubium'' which consists of the single species ''Cruschedula revola''. Description The genus was first described by Florentino Ameghino in his 1899 volume ''Sinopsis geológic ...
'' was formerly thought to belong to Spheniscidae; however, re-examination of the holotype in 1943 resulted in the genus being placed in
Accipitridae The Accipitridae is one of the three families within the order Accipitriformes, and is 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-s ...
. Further examination in 1980 resulted in placement as Aves ''incertae sedis''.


Taxonomy

Some recent sources apply the phylogenetic taxon Spheniscidae to what here is referred to as Spheniscinae. Furthermore, they restrict the phylogenetic taxon Sphenisciformes to flightless taxa, and establish the phylogenetic taxon Pansphenisciformes 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 A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spec ...
is presently resolved, this is confusing, so the established Linnean system is followed here.


Evolution

The
evolution Evolution is change in the heritable characteristics of biological populations over successive generations. These characteristics are the expressions of genes, which are passed on from parent to offspring during reproduction. Variation ...
ary history of penguins is well-researched and represents a showcase of evolutionary
biogeography Biogeography is the study of the distribution of species and ecosystems in geographic space and through geological time. Organisms and biological communities often vary in a regular fashion along geographic gradients of latitude, elevation, ...
. Although penguin bones of any one species vary much in size and few good specimens are known, the
alpha taxonomy In biology, taxonomy () is the science, scientific study of naming, defining (Circumscription (taxonomy), circumscribing) and classifying groups of biological organisms based on shared characteristics. Organisms are grouped into taxon, taxa (s ...
of many prehistoric forms still leaves much to be desired. Some seminal articles about penguin prehistory have been published since 2005;Supplementary Material
the evolution of the living genera can be considered resolved by now. The basal penguins lived around the time of the
Cretaceous–Paleogene extinction event The Cretaceous–Paleogene (K–Pg) extinction event (also known as the Cretaceous–Tertiary extinction) was a sudden mass extinction of three-quarters of the plant and animal species on Earth, approximately 66 million years ago. With the ...
somewhere in the general area of (southern) New Zealand and
Byrd Land Marie Byrd Land (MBL) is an unclaimed region of Antarctica. With an area of , it is the largest unclaimed territory on Earth. It was named after the wife of American naval officer Richard E. Byrd, who explored the region in the early 20th centur ...
, Antarctica. Due to
plate tectonics Plate tectonics (from the la, label=Late Latin, tectonicus, from the grc, τεκτονικός, lit=pertaining to building) is the generally accepted scientific theory that considers the Earth's lithosphere to comprise a number of large ...
, these areas were at that time less than apart rather than the of today. The
most recent common ancestor In biology and genetic genealogy, the most recent common ancestor (MRCA), also known as the last common ancestor (LCA) or concestor, of a set of organisms is the most recent individual from which all the organisms of the set are descended. The ...
of penguins and their
sister clade In phylogenetics, a sister group or sister taxon, also called an adelphotaxon, comprises the closest relative(s) of another given unit in an evolutionary tree. Definition The expression is most easily illustrated by a cladogram: Taxon A and t ...
can be roughly dated to the
Campanian The Campanian is the fifth of six ages of the Late Cretaceous Epoch on the geologic timescale of the International Commission on Stratigraphy (ICS). In chronostratigraphy, it is the fifth of six stages in the Upper Cretaceous Series. Campanian s ...
Maastrichtian The Maastrichtian () is, in the ICS geologic timescale, the latest age (uppermost stage) of the Late Cretaceous Epoch or Upper Cretaceous Series, the Cretaceous Period or System, and of the Mesozoic Era or Erathem. It spanned the interval from ...
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 The Cretaceous ( ) is a geological period that lasted from about 145 to 66 million years ago (Mya). It is the third and final period of the Mesozoic Era, as well as the longest. At around 79 million years, it is the longest geological period of th ...
, 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 web A food web is the natural interconnection of food chains and a graphical representation of what-eats-what in an ecological community. Another name for food web is consumer-resource system. Ecologists can broadly lump all life forms into one ...
s that follows the initial phase of mass extinctions because of their below-average dispersal capabilities (''see also''
Flightless cormorant The flightless cormorant (''Nannopterum harrisi''), also known as the Galapagos cormorant, is a cormorant endemic to the Galapagos Islands, and an example of the highly unusual fauna there. It is unique in that it is the only known cormorant t ...
).


Basal fossils

The oldest known
fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
penguin species is ''Waimanu manneringi'', which lived in the early
Paleocene The Paleocene, ( ) or Palaeocene, is a geological epoch (geology), epoch that lasted from about 66 to 56 mya (unit), million years ago (mya). It is the first epoch of the Paleogene Period (geology), Period in the modern Cenozoic Era (geology), E ...
epoch of New Zealand, or about 62
mya Mya may refer to: Brands and product names * Mya (program), an intelligent personal assistant created by Motorola * Mya (TV channel), an Italian Television channel * Midwest Young Artists, a comprehensive youth music program Codes * Burmese ...
. While they were not as well-adapted to aquatic life as modern penguins, ''
Waimanu ''Waimanu'' is a genus of early penguin which lived during the Paleocene, soon after the Cretaceous–Paleogene extinction event, around 62–60 million years ago. It was about the size of an emperor penguin (1 metre). It is one of the most impor ...
'' were generally
loon Loons (North American English) or divers (British / Irish English) are a group of aquatic birds found in much of North America and northern Eurasia. All living species of loons are members of the genus ''Gavia'', family Gaviidae and order Gavi ...
-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 (both living and extinct) – already adapting to underwater locomotion. ''
Perudyptes ''Perudyptes'' is a basal (phylogenetics), basal penguin from the Eocene, Middle Eocene Paracas Formation of Peru.Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...
proves that, by the
Bartonian The Bartonian is, in the ICS's geologic time scale, a stage or age in the middle Eocene Epoch or Series. The Bartonian Age spans the time between . It is preceded by the Lutetian and is followed by the Priabonian Age. Stratigraphic definitio ...
(Middle Eocene), some 39–38 mya, primitive penguins had spread to
South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...
and were in the process of expanding into
Atlantic The Atlantic Ocean is the second-largest of the world's five oceans, with an area of about . It covers approximately 20% of Earth's surface and about 29% of its water surface area. It is known to separate the " Old World" of Africa, Europe an ...
waters.


Palaeeudyptines

During the Late Eocene and the Early
Oligocene The Oligocene ( ) is a geologic epoch of the Paleogene Period and extends from about 33.9 million to 23 million years before the present ( to ). As with other older geologic periods, the rock beds that define the epoch are well identified but the ...
(40–30 mya), some lineages of gigantic penguins existed.
Nordenskjoeld's giant penguin ''Anthropornis'' is a genus of giant penguin that lived 45-33 million years ago, during the Late Eocene and the earliest part of the Oligocene.Myrcha, A., Jadwiszczak, P., Tambussi, C.P., Noriega, J.I., Gazdzicki, A., Tatur, A., and Valle, R.A. ...
was the tallest, growing nearly tall. The
New Zealand giant penguin ''Pachydyptes'' is an extinct genus of penguin. It contains the single species ''Pachydyptes ponderosus'', the New Zealand giant penguin. This taxon is known from a few bones from Late Eocene (37 to 34 MYA) rocks in the area of Otago, which we ...
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 In taxonomy (general), taxonomy, a group is paraphyletic if it consists of the group's most recent common ancestor, last common ancestor and most of its descendants, excluding a few Monophyly, monophyletic subgroups. The group is said to be pa ...
subfamily In biological classification, a subfamily (Latin: ', plural ') is an auxiliary (intermediate) taxonomic rank, next below family but more inclusive than genus. Standard nomenclature rules end subfamily botanical names with "-oideae", and zoologi ...
called
Palaeeudyptinae Palaeeudyptinae, the giant penguins, is a paraphyletic subfamily of prehistoric penguins. It includes several genera of medium-sized to very large species, such as ''Icadyptes salasi'', '' Palaeeudyptes marplesi'', ''Anthropornis nordenskjoeldi'', ...
. More recently, with new taxa being discovered and placed in the
phylogeny A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological spec ...
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 () refers to a geographical region that encompasses the southern end of South America, governed by Argentina and Chile. The region comprises the southern section of the Andes Mountains with lakes, fjords, temperate rainforests, and gl ...
, and at least one other—which is or includes the paleeudyptines as recognized today – occurred on most
Antarctic The Antarctic ( or , American English also or ; commonly ) is a polar region around Earth's South Pole, opposite the Arctic region around the North Pole. The Antarctic comprises the continent of Antarctica, the Kerguelen Plateau and other ...
and
Subantarctic The sub-Antarctic zone is a region in the Southern Hemisphere, located immediately north of the Antarctic region. This translates roughly to a latitude of between 46° and 60° south of the Equator. The subantarctic region includes many islands ...
coasts. But size plasticity seems to have been great at this initial stage of penguin
radiation In physics, radiation is the emission or transmission of energy in the form of waves or particles through space or through a material medium. This includes: * ''electromagnetic radiation'', such as radio waves, microwaves, infrared, visi ...
: on
Seymour Island Seymour Island or Marambio 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 the closest part of Antarctica to South America. It lies within the section of the isla ...
, Antarctica, for example, around 10 known species of penguins ranging in size from medium to huge apparently coexisted some 35 mya during the
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 . The Priabonian is preceded by the Bartonian and is followed by the Rupelian, the lowest stage of t ...
(Late Eocene). It is not even known whether the gigantic palaeeudyptines constitute a
monophyletic In cladistics for a group of organisms, monophyly is the condition of being a clade—that is, a group of taxa composed only of a common ancestor (or more precisely an ancestral population) and all of its lineal descendants. Monophyletic gro ...
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 is usually done these days (i.e., including ''
Anthropornis nordenskjoeldi ''Anthropornis'' is a genus of giant penguin that lived 45-33 million years ago, during the Late Eocene and the earliest part of the Oligocene.Myrcha, A., Jadwiszczak, P., Tambussi, C.P., Noriega, J.I., Gazdzicki, A., Tatur, A., and Valle, R.A ...
''). The oldest well-described giant penguin, the -tall ''
Icadyptes salasi ''Icadyptes'' is an extinct genus of giant penguins from the Late Eocene tropics of South America. Etymology The genus name is a combination of "''Ica''" for the Peruvian region where the type species was found and "dyptes" from the Greek w ...
'', actually occurred as far north as northern
Peru , image_flag = Flag of Peru.svg , image_coat = Escudo nacional del Perú.svg , other_symbol = Great Seal of the State , other_symbol_type = Seal (emblem), National seal , national_motto = "Fi ...
about 36 mya. In any case, the gigantic penguins had disappeared by the end of the
Paleogene The Paleogene ( ; British English, also spelled Palaeogene or Palæogene; informally Lower Tertiary or Early Tertiary) is a geologic period, geologic period and system that spans 43 million years from the end of the Cretaceous Period million yea ...
, around 25 mya. Their decline and disappearance coincided with the spread of the Squalodontoidea and other primitive, fish-eating
toothed whale The toothed whales (also called odontocetes, systematic name Odontoceti) are a parvorder of cetaceans that includes dolphins, porpoises, and all other whales possessing teeth, such as the beaked whales and sperm whales. Seventy-three species of t ...
s, which certainly competed with them for food, and were ultimately more successful. A new lineage, the
Paraptenodytes ''Paraptenodytes'' is an extinct genus of penguins which contains two or three species sized between a Magellanic penguin and an emperor penguin (''Aptenodytes forsteri''). They are known from fossil bones ranging from a partial skeleton and some ...
, 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 ''Palaeospheniscus'' is an extinct genus of penguins belonging to the subfamily Palaeospheniscinae. These penguins are apparently not closely related to the modern genus ''Spheniscus''. Description The species of ''Palaeospheniscus'' were medium ...
, as well as the radiation that gave rise to the penguin
biodiversity Biodiversity or biological diversity is the variety and variability of life on Earth. Biodiversity is a measure of variation at the genetic (''genetic variability''), species (''species diversity''), and ecosystem (''ecosystem diversity'') l ...
of our time.


Origin and systematics of modern penguins

Modern penguins constitute two undisputed clades and another two more basal genera with more ambiguous relationships. To help resolve the evolution of this Order (biology), order, 19 high-coverage genomes that, together with two previously published genomes, encompass all extant penguin species have been sequenced. 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. Presumably 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 and
Patagonia Patagonia () refers to a geographical region that encompasses the southern end of South America, governed by Argentina and Chile. The region comprises the southern section of the Andes Mountains with lakes, fjords, temperate rainforests, and gl ...
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 the chicks are almost naked. This genus has a distribution centred 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, centred on Antarctic coasts but extending somewhat northwards from there. In external morphology (biology), morphology, these apparently still resemble the common ancestor of the Spheniscinae, as ''Aptenodytes'' autapomorphies are, in most cases, fairly pronounced Adaptation (biology), 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. The Genus, genera ''Spheniscus'' and ''
Eudyptula The genus ''Eudyptula'' ("good little diver") contains two species of penguin, found in southern Australia, Tasmania, and New Zealand (including the Chatham Islands). They are commonly known as the little penguin, little blue penguin, or, in Aus ...
'' contain species with a mostly Subantarctic distribution centred on
South America South America is a continent entirely in the Western Hemisphere and mostly in the Southern Hemisphere, with a relatively small portion in the Northern Hemisphere at the northern tip of the continent. It can also be described as the southe ...
; some, however, range quite far northwards. They all lack carotenoid colouration 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 out of the ancestral range of modern penguins throughout the Chattian (Late Oligocene), starting approximately 28 mya. 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. The ''Megadyptes''–''Eudyptes'' clade occurs at similar latitudes (though not as far north as the
Galápagos penguin The Galápagos penguin (''Spheniscus mendiculus'') is a penguin endemic to the Galápagos Islands, Ecuador. It is the only penguin found north of the equator. Most inhabit Fernandina Island and the west coast of Isabela Island. The cool waters ...
), has its highest diversity in the New Zealand region, and represents 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.


Geography

The geographical and temporal pattern of spheniscine evolution corresponds closely to two episodes of global cooling documented in the Paleoclimatology, paleoclimatic record. 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 Quaternary glaciation, 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. Despite this, there is no fossil evidence to support the idea of crown radiation from the Antarctic continent in the Paleogene, although DNA study favors such a radiation. 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 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'' is a genus of early penguin which lived during the Paleocene, soon after the Cretaceous–Paleogene extinction event, around 62–60 million years ago. It was about the size of an emperor penguin (1 metre). It is one of the most impor ...
'' remains unknown and not well-resolved by molecular or morphological analyses. The latter tend to be confounded by the strong adaptive Autapomorphy, 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 for paleognaths and fowl) that comprises what is sometimes called "Aequornithes, higher waterbirds" to distinguish them from the more ancient waterfowl. This group contains such birds as storks, Rallidae, rails, and the seabirds, with the possible exception of the
Charadriiformes Charadriiformes (, from ''Charadrius'', the type genus of family Charadriidae) is a diverse order of small to medium-large birds. It includes about 390 species and has members in all parts of the world. Most charadriiform birds live near water an ...
. Inside this group, penguin relationships are far less clear. Depending on the analysis and dataset, a close relationship to Ciconiiformes or to Procellariiformes has been suggested. Some think the penguin-like Plotopteridae, plotopterids (usually considered relatives of cormorants and anhingas) may actually be a sister group of the penguins and those 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 into three. A 2014 analysis of whole genomes of 48 representative bird species has concluded that penguins are the sister group of Procellariiformes, from which they diverged about 60 million years ago (95% CI, 56.8-62.7). The distantly related puffins, which live in the North Pacific and North Atlantic, developed similar characteristics to survive in the Arctic and sub-Arctic environments. Like the penguins, puffins have a white chest, black back and short stubby wings providing excellent swimming ability in icy water. But, unlike penguins, puffins can fly, as flightless birds would not survive alongside land-based predators such as polar bears and foxes; there are no such predators in the Antarctic. Their similarities indicate that similar environments, although at great distances, can result in similar evolutionary developments, i.e. convergent evolution.


Anatomy and physiology

Penguins are superbly adapted to Aquatic ecosystem, aquatic life. Their wings have evolved to become flippers, useless for flight in the air. In the water, however, penguins are astonishingly agile. Penguins' swimming looks very similar to birds' flight in the air. Within the smooth
plumage Plumage ( "feather") is a layer of feathers that covers a bird and the pattern, colour, and arrangement of those feathers. The pattern and colours of plumage differ between species and subspecies and may vary with age classes. Within species, ...
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 Countershading, or Thayer's law, is a method of camouflage in which an animal's coloration is darker on the top or upper side and lighter on the underside of the body. This pattern is found in many species of mammals, reptiles, birds, fish, and ...
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. Gentoo penguins are the fastest underwater birds in the world. They are capable of reaching speeds up to 36 km (about 22 miles) per hour while searching for food or escaping from predators. They are also able to dive to depths of 170–200 meters (about 560–660 feet). 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. Emperor penguins are the world's deepest-diving birds. They can dive to depths of approximately 550 meters (1,800 feet) while searching for food. Penguins either waddle on their feet or slide on their bellies across the snow while using their feet to propel and steer themselves, 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 (sense), hearing for birds; this is used by parents and chicks to locate one another in crowded Seabird colony, 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 emperor penguin (''Aptenodytes forsteri'') 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 length and weighing from . Feathers of th ...
has a maximum feather density of about nine feathers per square centimeter which is actually much lower than other birds that live in antarctic environments. However, they have been identified as having at least four different ''types'' of feather: in addition to the traditional feather, the emperor has afterfeathers, Down feather, plumules, and filoplumes. The afterfeathers are downy plumes that attach directly to the main feathers and were once believed to account for the bird's ability to conserve heat when under water; the plumules are small down feathers that attach directly to the skin, and are much more dense in penguins than other birds; lastly the filoplumes are small (less than 1 cm long) naked shafts that end in a splay of fibers— filoplumes were believed to give flying birds a sense of where their plumage was and whether or not it needed preening, so their presence in penguins may seem inconsistent, but penguins also preen extensively. The emperor 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 centre of the heat pack. Calculations of the heat loss and retention ability of marine endotherms suggest that most extant penguins are too small to survive in such cold environments. In 2007, Thomas and Fordyce wrote about the "heterothermic loophole" that penguins utilize in order to survive in Antarctica. All extant penguins, even those that live in warmer climates, have a counter-current heat exchanger called the humeral plexus. The flippers of penguins have at least three branches of the axillary artery, which allows cold blood to be heated by blood that has already been warmed and limits heat loss from the flippers. This system allows penguins to efficiently use their body heat and explains why such small animals can survive in the extreme cold. 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
great auk The great auk (''Pinguinus impennis'') is a species of flightless alcid that became extinct in the mid-19th century. It was the only modern species in the genus ''Pinguinus''. It is not closely related to the birds now known as penguins, wh ...
of the Northern Hemisphere, now extinct, was superficially similar to penguins, and the word ''penguin'' was originally used for that bird centuries ago. They are only distantly related to the penguins, but are an example of convergent evolution.


Isabelline penguins

Perhaps one in 50,000 penguins (of most species) are born with brown rather than black plumage. These are called Isabelline (colour), isabelline penguins. 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 almost 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. Several species live in the temperate zone; one, the
Galápagos penguin The Galápagos penguin (''Spheniscus mendiculus'') is a penguin endemic to the Galápagos Islands, Ecuador. It is the only penguin found north of the equator. Most inhabit Fernandina Island and the west coast of Isabela Island. The cool waters ...
, 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. Also, though the climate of the Arctic and Antarctic regions is similar, there are no penguins found in the Arctic. 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 Angola, Antarctica,
Argentina Argentina (), officially the Argentine Republic ( es, link=no, República Argentina), is a country in the southern half of South America. Argentina covers an area of , making it the second-largest country in South America after Brazil, th ...
, Australia, Chile, Namibia, New Zealand, and South Africa. Satellite images and photos released in 2018 show the population of 2 million in France's remote Île aux Cochons, Ile aux Cochons has collapsed, with barely 200,000 remaining, according to a study published in Antarctic Science.


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 100 pairs for gentoo penguins to several hundred thousand in the case of king, macaroni and chinstrap penguins. Williams, p. 17 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. Williams, p. 57 ''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 penguins, lay only one. Williams, p. 23 With the exception of the emperor penguin, where the male does it all, all penguins share the Avian incubation, 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%. The relatively thick shell forms between 10 and 16% of the weight of a penguin egg, presumably to reduce the effects of dehydration and to minimize the 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 the chick if the parents are delayed in returning with food. Williams, p. 24 When emperor penguin 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 and king penguins, the chicks assemble in large groups called Crèche (zoology), crèches.


Conservation status

The majority of living penguin species have declining populations. According to the IUCN Red List, their conservation statuses range from Least Concern through to Endangered.


Penguins and humans

Penguins have no special fear of humans and will often approach groups of people. This is probably because penguins have no land predators in Antarctica or the nearby offshore islands. They are preyed upon by other birds like skuas, especially in eggs and as fledglings. Other birds like petrels, sheathbills, and gulls also eat the chicks. Dogs preyed upon penguins while they were allowed in Antarctica during the age of early human exploration as sled dogs, but dogs have long since been banned from Antarctica. Instead, adult penguins are at risk at sea from predators such as sharks, orcas, and leopard seals. Typically, penguins do not approach closer than around 9 feet (3 meters), at which point they appear to become nervous. In June 2011, an emperor penguin came ashore on New Zealand's Peka Peka Beach, off course on its journey to Antarctica. Nicknamed Happy Feet, after the Happy Feet, film of the same name, it was suffering from heat exhaustion and had to undergo a number of operations to remove objects like driftwood and sand from its stomach. Happy Feet was a media sensation, with extensive coverage on TV and the web, including a live stream that had thousands of views and a visit from English actor Stephen Fry. Once he had recovered, Happy Feet was released back into the water south of New Zealand.


In popular culture

Penguins are widely considered endearing for their unusually upright, waddling gait, swimming ability and (compared to other birds) lack of fear of humans. Their black-and-white plumage is often likened to a white tie suit. Some writers and artists have penguins based at the North Pole, but there are no wild penguins in the Arctic. The cartoon series ''Chilly Willy'' helped perpetuate this myth, as the title penguin would interact with Arctic or Subarctic, sub-Arctic species, such as polar bears and walruses. Penguins have been the subject of many books and films, such as ''Happy Feet'', ''Surf's Up (film), Surf's Up'' and ''Penguins of Madagascar'', all Computer-generated imagery, CGI films; ''March of the Penguins'', a documentary based on the Bird migration, migration process of the
emperor penguin The emperor penguin (''Aptenodytes forsteri'') 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 length and weighing from . Feathers of th ...
; and ''Farce of the Penguins'', a parody of the documentary. ''Mr. Popper's Penguins'' is a children's book written by Richard and Florence Atwater; it was named a Newbery Honor Book in 1939. Penguins have also appeared in a number of cartoons and television dramas, including ''Pingu'', created by Silvio Mazzola in 1986 and covering more than 100 short episodes. At the end of 2009, ''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." A video game called ''Pengo (video game), Pengo'' was released by Sega in 1982. Set in Antarctica, the player controls a penguin character who must navigate mazes of ice cubes. The player is rewarded with cut-scenes of animated penguins marching, dancing, saluting and playing peekaboo. Several remakes and enhanced editions have followed, most recently in 2012. Penguins are also sometimes depicted in music.Shuker, R. (2012). ''Understanding popular music culture''. Routledge. In 1941, DC Comics introduced the avian-themed character of the Penguin (character), Penguin as a supervillain adversary of the superhero Batman (''Detective Comics'' #58). He became one of the most enduring enemies in List of Batman family enemies#Classic rogues gallery, Batman's rogues gallery. In the 60s ''Batman (TV series), Batman'' TV series, as played by Burgess Meredith, he was one of the most popular characters, and in Tim Burton's reimagining of the character in the 1992 film ''Batman Returns'', he employed an actual army of penguins (mostly African penguins and king penguins). Several pro, minor, college and high school sport teams in the United States have named themselves after the species, including the Pittsburgh Penguins team in the National Hockey League and the Youngstown State Penguins in college athletics. Penguins featured regularly in the cartoons of U.K. cartoonist Steve Bell (cartoonist), Steve Bell in his strip in ''The Guardian'' newspaper, particularly during and following the Falklands War. Opus the Penguin, from the cartoons of Berkeley Breathed, is also described as hailing from the Falklands. Opus was a comical, "existentialist" penguin character in the cartoons ''Bloom County'', ''Outland (comic strip), Outland'' and ''Opus (comic strip), Opus''. He was also the star in the animated Christmas TV special ''A Wish for Wings That Work''. In the mid-2000s, penguins became one of the most publicized species of animals that form lasting Homosexuality in animals#Penguins, homosexual couples. A Children's literature, children's book, ''And Tango Makes Three'', was written about Roy and Silo, one such penguin family in the Central Park Zoo, New York Zoo.


References


Bibliography

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External links


Two new fossil penguin species found in Peru
news.nationalgeographic.com
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 the Encyclopedia of New Zealand
Seaworld Penguin Information

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

Curious Penguins

Live 24/7 camera inside a penguin habitat
{{Authority control Articles containing video clips Flightless birds Penguins, Seabirds Spheniscidae, Spheniscinae, Sphenisciformes, Danian first appearances Taxa named by Charles Lucien Bonaparte Extant Danian first appearances