Penguin

The word penguin first appears in literature at the end of the 16th century as a synonym for the great auk. When European explorers discovered what are today known as penguins in the Southern Hemisphere, they noticed their similar appearance to the great auk of the Northern Hemisphere and named them after this bird, although they are not closely related. Breton or Spanish origin (the latter two are attributed to the French word ), but first appears in English or Dutch. including the Oxford English Dictionary, the American Heritage Dictionary, the Century Dictionary on the basis that the name was originally applied to the great auk, either because it was found on White Head Island () in Newfoundland, or because it had white circles around its eyes (though the head was black). However, the Welsh word can also be used to mean 'end' and, in a maritime context, means 'front end or part, bow (of a ship), prow'. An alternative etymology links the word to Latin , 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 . A group of penguins in the water is sometimes called a raft. Pinguinus Since 1791, the Latin word Pinguinus has been used in scientific classification to name the genus of the great auk (Pinguinus impennis, meaning "plump or fat without flight feathers"), which became extinct in the mid-19th century. 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 Lucien Bonaparte in several distinct genera within the family Spheniscidae and order Sphenisciformes. ==Systematics and evolution==

Taxonomy The family name of Spheniscidae was given by Charles Lucien Bonaparte from the genus Spheniscus, the name of that genus comes from the Greek word sphēn "wedge" used for the shape of an African penguin's swimming flippers. Some recent sources The International Ornithologists' Union recognizes six genera and eighteen species: Evolution , Tasmania Although the evolutionary and biogeographic history of Sphenisciformes is well-researched, many prehistoric forms are not fully described. Some seminal articles about the evolutionary history of penguins have been published since 2005. The basal penguins lived around the time of the Cretaceous–Paleogene extinction event in the general area of southern New Zealand and Byrd Land, Antarctica. Basal fossils The oldest known fossil penguin species are known from the Waipara Greensand of New Zealand, which spans the late Danian to early Thanetian stages (~62.5–58 Ma) of the Paleocene epoch. Several genera have been named from these outcrops, including Archaeodyptes, Daniadyptes, Muriwaimanu, Sequiwaimanu, Waimanu, Waimanutaha, and Waiparadyptes. While they were not as well-adapted to aquatic life as modern penguins, they were still flightless, with short wings adapted for deep diving. Perudyptes from northern Peru was dated to 42 mya. An unnamed fossil from Argentina proves that, by the Bartonian (Middle Eocene), some 39–38 mya, primitive penguins had spread to South America and were in the process of expanding into Atlantic waters. 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. 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, 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 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 Charadriiform 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 in different parts of the world can result in similar evolutionary developments, i.e. convergent evolution. Puffins are auks (Alcidae), akin to the aforementioned great auk, which have a greater resemblance to "true" penguins after converging on more features of their anatomy. ==Anatomy and physiology==

Penguins are superbly adapted to 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 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. 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 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 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 the 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 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, plumules, and filoplumes. The afterfeathers are downy plumes that attach directly to the main feathers and were once thought 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 thought 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. on Gourdin Island Around one in 50,000 penguins (of most species) are born with brown rather than black plumage. These are called 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. ==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 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, where the male does it all, 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 per year; 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 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. 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 crèches. ==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, 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, 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 Ile aux Cochons has collapsed, with barely 200,000 remaining, according to a study published in Antarctic Science. 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==

(center) encountering humans during the Antarctic summer 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 , 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 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 , the mascot of the Linux kernel 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 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 and Penguins of Madagascar, all CGI films; March of the Penguins, a documentary based on the migration process of the emperor penguin; 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, co-created by Otmar Gutmann and Erika Brueggemann in 1990 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 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. In 1941, DC Comics introduced the avian-themed character of the Penguin as a supervillain adversary of the superhero Batman (Detective Comics #58). He became one of the most enduring enemies in Batman's rogues gallery. In the 60s Batman TV series, as played by Burgess Meredith, he was one of the most popular characters, and in Tim Burton's reimagining of the story, the character played by Danny Devito in the 1992 film Batman Returns, 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 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 and 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 homosexual couples. A children's book, And Tango Makes Three, was written about one such penguin family in the New York Zoo. ==References==