180-462: 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 100 cm (39 in) in length and weighing from 22 to 45 kg (49 to 99 lb). Feathers of the head and back are black and sharply delineated from the white belly, pale-yellow breast and bright-yellow ear patches. Like all species of penguin,
360-519: 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
540-501: A bird's lifetime. Activational hormones occur during puberty and adulthood and serve to 'activate' certain behaviors when appropriate, such as territoriality during breeding season. Organizational hormones occur only during a critical period early in development, either just before or just after hatching in most birds, and determine patterns of behavior for the rest of the bird's life. Such behavioral differences can cause disproportionate sensitivities to anthropogenic pressures. Females of
720-544: A branch which led to all other living penguin species. Mitochondrial and nuclear DNA evidence suggests this split occurred around 40 million years ago. Adult emperor penguins are 110–120 cm (43–47 in) in length, averaging 115 cm (45 in) according to Stonehouse (1975). Due to the method of bird measurement that measures length between bill to tail, sometimes body length and standing height are confused, and some reported height even reaching 1.5 m (4 ft 11 in) tall. There are still more than
900-454: 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. 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;
1080-535: 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
1260-459: A diverse array of sexually dimorphic traits. Aggressive utility traits such as "battle" teeth and blunt heads reinforced as battering rams are used as weapons in aggressive interactions between rivals. Passive displays such as ornamental feathering or song-calling have also evolved mainly through sexual selection. These differences may be subtle or exaggerated and may be subjected to sexual selection and natural selection . The opposite of dimorphism
1440-726: A few other facilities in China, and the only confirmed twin emperor penguins (the species normally lays just one egg) hatched at Sun Asia Ocean World in Dalian in 2017. In Japan, the species is housed at Port of Nagoya Public Aquarium and Wakayama Adventure World , with successful hatching at Adventure World. In June 2011, a juvenile emperor penguin was found on the beach at Peka Peka , north of Wellington in New Zealand. He had consumed 3 kg (6.6 lb) of sand, which he had apparently mistaken for snow, as well as sticks and stones, and had to undergo
1620-783: A few papers mentioning that they reach a standing height of 1.2 m (3 ft 11 in) instead of body length. Although standing height of emperor penguin is rarely provided at scientific reports, Prévost (1961) recorded 86 wild individuals and measured maximum height of 1.08 m (3 ft 7 in). Friedman (1945) recorded measurements from 22 wild individuals and resulted height ranging 83–97 cm (33–38 in). Ksepka et al . (2012) measured standing height of 81–94 cm (32–37 in) according to 11 complete skins collected in American Museum of Natural History . The weight ranges from 22.7 to 45.4 kg (50 to 100 lb) and varies by sex, with males weighing more than females. It
1800-635: A few zoos and public aquariums in North America and Asia. Emperor penguins were first successfully bred at SeaWorld San Diego ; more than 20 birds have hatched there since 1980. Considered a flagship species , 55 individuals were counted in captivity in North American zoos and aquaria in 1999. In China, the emperor penguin was first bred at Nanjing Underwater World in 2009, followed by Laohutan Ocean Park in Dalian in 2010. Since then it has been kept and bred at
1980-432: A fourth process involves an increase in the breakdown of fats by enzymes, which is induced by the hormone glucagon . At temperatures above 20 °C (68 °F), an emperor penguin may become agitated as its body temperature and metabolic rate rise to increase heat loss. Raising its wings and exposing the undersides increases the exposure of its body surface to the air by 16%, facilitating further heat loss. In addition to
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#17328515832752160-539: A frequency-modulated whistle to beg for food and to contact parents. The emperor penguin breeds in the coldest environment of any bird species; air temperatures may reach −40 °C (−40 °F), and wind speeds may reach 144 km/h (89 mph). Water temperature is a frigid −1.8 °C (28.8 °F), which is much lower than the emperor penguin's average body temperature of 39 °C (102 °F). The species has adapted in several ways to counteract heat loss. Dense feathers provide 80–90% of its insulation and it has
2340-458: A group of penguins on land is a waddle , and a group of penguins in the water is a raft . Since 1871, 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. As confirmed by a 2004 genetic study, the genus Pinguinus belongs in
2520-553: A large role in the changing of sex by the fish. It is often seen that a fish will change its sex when there is a lack of a dominant male within the social hierarchy. The females that change sex are often those who attain and preserve an initial size advantage early in life. In either case, females which change sex to males are larger and often prove to be a good example of dimorphism. In other cases with fish, males will go through noticeable changes in body size, and females will go through morphological changes that can only be seen inside of
2700-413: A layer of sub- dermal fat which may be up to 3 cm (1.2 in) thick before breeding. While the density of contour feathers is approximately 9 per square centimetre (58 per square inch), a combination of dense afterfeathers and down feathers (plumules) likely play a critical role for insulation. Muscles allow the feathers to be held erect on land, reducing heat loss by trapping a layer of air next to
2880-959: A less bright or less exaggerated color during the off-breeding season. This occurs because the species is more focused on survival than on reproduction, causing a shift into a less ornate state. Consequently, sexual dimorphism has important ramifications for conservation. However, sexual dimorphism is not only found in birds and is thus important to the conservation of many animals. Such differences in form and behavior can lead to sexual segregation , defined as sex differences in space and resource use. Most sexual segregation research has been done on ungulates, but such research extends to bats , kangaroos , and birds. Sex-specific conservation plans have even been suggested for species with pronounced sexual segregation. The term sesquimorphism (the Latin numeral prefix sesqui - means one-and-one-half, so halfway between mono - (one) and di - (two)) has been proposed for bird species in which "both sexes have basically
3060-424: A maritime context, pen blaen means 'front end or part, bow (of a ship), prow'. An alternative etymology links the word to Latin pinguis , which means 'fat' or 'oil'. Support for this etymology can be found in the alternative Germanic word for penguin, fettgans or 'fat-goose', and the related Dutch word vetgans . Adult male penguins are sometimes called cocks , females sometimes called hens ;
3240-473: A mostly Subantarctic distribution centred on South America ; 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
3420-425: A naturally occurring part of development, for example plumage. In addition, the strong hormonal influence on phenotypic differences suggests that the genetic mechanism and genetic basis of these sexually dimorphic traits may involve transcription factors or cofactors rather than regulatory sequences. Sexual dimorphism may also influence differences in parental investment during times of food scarcity. For example, in
3600-455: A number of colonies have been reported on shelf ice rather than sea ice , in some cases moving to the shelf in years when sea ice forms late. The northernmost breeding population is on Snow Hill Island , near the northern tip of the Peninsula. Individual vagrants have been seen on Heard Island , South Georgia , and occasionally in New Zealand. The furthest north a vagrant has been recorded
3780-487: A number of operations to remove these to save his life. Following recovery, on 4 September, the juvenile, named "Happy Feet" (after the 2006 film ), was fitted with a tracking device and released into the Southern Ocean 80 km (50 mi) north of Campbell Island . However, 8 days later scientists lost contact with the bird, suggesting that the transmitter had fallen off (considered likely) or that he had been eaten by
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#17328515832753960-500: A one-hour programme dedicated to the species in the 2018 series Dynasties . The animated movie Happy Feet (2006, followed by a sequel Happy Feet Two , 2011) features emperor penguins as its primary characters, with one in particular that loves to dance; although a comedy, it too depicts their life cycle and promotes an underlying serious environmental message of threats from global warming and depletion of food sources by overfishing. The animated movie Surf's Up (2007) features
4140-449: A predator (considered less likely). The species' unique life cycle in such a harsh environment has been described in print and visual media. Apsley Cherry-Garrard , the Antarctic explorer, wrote in 1922: "Take it all in all, I do not believe anybody on Earth has a worse time than an emperor penguin". Widely distributed in cinemas in 2005, the French documentary La Marche de l'empereur , which
4320-520: A region around 2,000 km south of the equator 35 mya , during the Late Eocene , a climate decidedly warmer than today. 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
4500-414: A significant role in male reproductive success. Males have a propensity to be larger than females of a comparable age but it is unclear whether the size increase is due to a growth spurt at the time of the sexual transition or due to the history of faster growth in sex changing individuals. Larger males are able to stifle the growth of females and control environmental resources. Social organization plays
4680-575: A small female had dived to a depth of 535 m (1,755 ft) near McMurdo Sound . It is possible that emperor penguins can dive for even deeper and longer periods, as the accuracy of the recording devices is diminished at greater depths. Further study of one bird's diving behaviour revealed regular dives to 150 m (490 ft) in water around 900 m (3,000 ft) deep, and shallow dives of less than 50 m (160 ft), interspersed with deep dives of more than 400 m (1,300 ft) in depths of 450 to 500 m (1,480 to 1,640 ft). This
4860-537: A speciation phenomenon if the variation becomes strongly drastic and favorable towards two different outcomes. Sexual dimorphism is maintained by the counteracting pressures of natural selection and sexual selection. For example, sexual dimorphism in coloration increases the vulnerability of bird species to predation by European sparrowhawks in Denmark. Presumably, increased sexual dimorphism means males are brighter and more conspicuous, leading to increased predation. Moreover,
5040-408: A spiny tongue and powerful jaws to grip slippery prey. They spend about half of their lives on land and the other half in the sea. The largest living species is the emperor penguin ( Aptenodytes forsteri ): on average, adults are about 1.1 m (3 ft 7 in) tall and weigh 35 kg (77 lb). The smallest penguin species is the little blue penguin ( Eudyptula minor ), also known as
5220-590: A study from the Woods Hole Oceanographic Institution concluded that global climate change could push the emperor penguin to the brink of extinction by the year 2100. The study constructed a mathematical model to predict how the loss of sea ice from climate warming would affect a big colony of emperor penguins at Terre Adélie , Antarctica. The study forecasted an 87% decline in the colony's population, from three thousand breeding pairs in 2009 to four hundred breeding pairs in 2100. Another study by
5400-419: A surfing emperor penguin named Zeke "Big-Z" Topanga. More than 30 countries have depicted the bird on their stamps – Australia, Great Britain, Chile and France have each issued several. It has also been depicted on a 1962 10 franc stamp as part of an Antarctic expedition series. Canadian band The Tragically Hip composed the song "Emperor Penguin" for their 1998 album Phantom Power . The Emperor Lays an Egg
5580-474: Is Lamprologus callipterus , a type of cichlid fish. In this fish, the males are characterized as being up to 60 times larger than the females. The male's increased size is believed to be advantageous because males collect and defend empty snail shells in each of which a female breeds. Males must be larger and more powerful in order to collect the largest shells. The female's body size must remain small because in order for her to breed, she must lay her eggs inside
Emperor penguin - Misplaced Pages Continue
5760-537: Is Lasioglossum hemichalceum , which is a species of sweat bee that shows drastic physical dimorphisms between male offspring. Not all dimorphism has to have a drastic difference between the sexes. Andrena agilissima is a mining bee where the females only have a slightly larger head than the males. Weaponry leads to increased fitness by increasing success in male–male competition in many insect species. The beetle horns in Onthophagus taurus are enlarged growths of
5940-627: Is monomorphism , when both biological sexes are phenotypically indistinguishable from each other. Common and easily identified types of dimorphism consist of ornamentation and coloration, though not always apparent. A difference in the coloration of sexes within a given species is called sexual dichromatism, commonly seen in many species of birds and reptiles. Sexual selection leads to exaggerated dimorphic traits that are used predominantly in competition over mates. The increased fitness resulting from ornamentation offsets its cost to produce or maintain, suggesting complex evolutionary implications, but
6120-484: Is a 2004 non-fiction children's picture book by Brenda Z. Guiberson. DC Comics ' crime boss character Oswald Chesterfield Cobblepot , aka "The Penguin", styles himself after an emperor penguin, a fact which is often referenced in stories, e.g., in his occasional alias "Forster Aptenodytes." Penguin For prehistoric genera, see List of penguins#Fossil genera Penguins are a group of aquatic flightless birds from
6300-423: Is a good indicator for females because it shows that they are good at obtaining a food supply from which the carotenoid is obtained. There is a positive correlation between the chromas of the tail and breast feathers and body condition. Carotenoids play an important role in immune function for many animals, so carotenoid dependent signals might indicate health. Frogs constitute another conspicuous illustration of
6480-455: Is a priority to mate and breed which usually precludes waiting for the previous year's partner to arrive at the colony. The female penguin lays one 460–470 g (16–17 oz) egg in May or early June; it is vaguely pear-shaped, pale greenish-white, and measures around 12 cm × 8 cm (4.7 in × 3.1 in). It represents just 2.3% of its mother's body weight, making it one of
6660-407: Is a sexually dimorphic trait. Theropoda It has been hypothesized that male theropods possessed a retractable penis, a feature similar to modern day crocodilians . Crocodilian skeletons were examined to determine whether there is a skeletal component that is distinctive between both sexes, to help provide an insight on the physical disparities between male and female theropods. Findings revealed
6840-423: Is advantageous to both parties because it avoids damaging the developing fruit and wasting the pollinator's effort on unrewarding visits. In effect, the strategy ensures that pollinators can expect a reward every time they visit an appropriately advertising flower. Females of the aquatic plant Vallisneria americana have floating flowers attached by a long flower stalk that are fertilized if they contact one of
7020-587: Is also displayed by dichromatism. In butterfly genera Bicyclus and Junonia , dimorphic wing patterns evolved due to sex-limited expression, which mediates the intralocus sexual conflict and leads to increased fitness in males. The sexual dichromatic nature of Bicyclus anynana is reflected by female selection on the basis of dorsal UV-reflective eyespot pupils. The common brimstone also displays sexual dichromatism; males have yellow and iridescent wings, while female wings are white and non-iridescent. Naturally selected deviation in protective female coloration
7200-673: Is also seen in frog species like P. bibroni i . Male painted dragon lizards, Ctenophorus pictus . are brightly conspicuous in their breeding coloration, but male colour declines with aging . Male coloration appears to reflect innate anti-oxidation capacity that protects against oxidative DNA damage . Male breeding coloration is likely an indicator to females of the underlying level of oxidative DNA damage (a significant component of aging) in potential mates. Possible mechanisms have been proposed to explain macroevolution of sexual size dimorphism in birds. These include sexual selection, selection for fecundity in females, niche divergence between
7380-470: Is believed that this is obtained by the ingestion of green Lepidopteran larvae, which contain large amounts of the carotenoids lutein and zeaxanthin . This diet also affects the sexually dimorphic colours in the human-invisible ultraviolet spectrum. Hence, the male birds, although appearing yellow to humans, actually have a violet-tinted plumage that is seen by females. This plumage is thought to be an indicator of male parental abilities. Perhaps this
Emperor penguin - Misplaced Pages Continue
7560-410: Is delayed or fails to return to the colony, the lone parent will return to the sea to feed, leaving the chick to die. Abandoned eggs do not hatch and orphaned chicks never survive. Female emperors who failed to find a mate to breed with, or have lost their own chick may attempt to adopt a stray chick or steal the chick of another female. The mother of the chick and neighboring females will fight to protect
7740-410: Is displayed in mimetic butterflies. Many arachnid groups exhibit sexual dimorphism, but it is most widely studied in the spiders. In the orb-weaving spider Zygiella x-notata , for example, adult females have a larger body size than adult males. Size dimorphism shows a correlation with sexual cannibalism , which is prominent in spiders (it is also found in insects such as praying mantises ). In
7920-616: Is essential for surviving the low Antarctic temperatures. From early November, chicks begin moulting into juvenile plumage, which takes up to two months and is usually not completed by the time they leave the colony. Adults cease feeding them during this time. All birds make the considerably shorter trek to the sea in December and January. The birds spend the rest of the summer feeding there. The emperor penguin's diet consists mainly of fish, crustaceans and cephalopods , although its composition varies from population to population. Fish are usually
8100-548: Is in honour of the German naturalist Johann Reinhold Forster , who accompanied Captain James Cook on his second voyage and officially named five other penguin species. Forster may have been the first person to see emperor penguins in 1773–74, when he recorded a sighting of what he believed was the similar king penguin ( A. patagonicus ) but given the location, may very well have been the emperor penguin ( A. forsteri ). Together with
8280-687: Is known in ceratopsids, although there is evidence that the more primitive ceratopsian Protoceratops andrewsi possessed sexes that were distinguishable based on frill and nasal prominence size. This is consistent with other known tetrapod groups where midsized animals tend to exhibit markedly more sexual dimorphism than larger ones. However, it has been proposed that these differences can be better explained by intraspecific and ontogenic variation rather than sexual dimorphism. In addition, many sexually dimorphic traits that may have existed in ceratopsians include soft tissue variations such as coloration or dewlaps , which would be unlikely to have been preserved in
8460-678: Is more prominently selected for in less dimorphic species of spiders, which often selects for larger male size. In the species Maratus volans , the males are known for their characteristic colorful fan which attracts the females during mating. Ray-finned fish are an ancient and diverse class, with the widest degree of sexual dimorphism of any animal class. Fairbairn notes that "females are generally larger than males but males are often larger in species with male–male combat or male paternal care ... [sizes range] from dwarf males to males more than 12 times heavier than females." There are cases where males are substantially larger than females. An example
8640-460: 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
8820-402: Is of a subdued brown coloration. The plumage of the peacock increases its vulnerability to predators because it is a hindrance in flight, and it renders the bird conspicuous in general. Similar examples are manifold, such as in birds of paradise and argus pheasants . Another example of sexual dichromatism is that of nestling blue tits . Males are chromatically more yellow than females. It
9000-451: Is or includes the paleeudyptines as recognized today – occurred on most Antarctic and Subantarctic coasts. Size plasticity was significant at this initial stage of radiation : on Seymour Island , Antarctica, for example, around 10 known species of penguins ranging in size from medium to large apparently coexisted some 35 mya during the Priabonian (Late Eocene). It is not known whether
9180-431: Is reduced to as low as 15–20 beats per minute and non-essential organs are shut down, thus facilitating longer dives. Its haemoglobin and myoglobin are able to bind and transport oxygen at low blood concentrations; this allows the bird to function with very low oxygen levels that would otherwise result in loss of consciousness. The emperor penguin has a circumpolar distribution in the Antarctic almost exclusively between
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#17328515832759360-434: Is seen in the bee species Macrotera portalis in which there is a small-headed morph, capable of flight, and large-headed morph, incapable of flight, for males. Anthidium manicatum also displays male-biased sexual dimorphism. The selection for larger size in males rather than females in this species may have resulted due to their aggressive territorial behavior and subsequent differential mating success. Another example
9540-480: Is selected for, which is seen in the family Araneidae . All Argiope species, including Argiope bruennichi , use this method. Some males evolved ornamentation including binding the female with silk, having proportionally longer legs, modifying the female's web, mating while the female is feeding, or providing a nuptial gift in response to sexual cannibalism. Male body size is not under selection due to cannibalism in all spider species such as Nephila pilipes , but
9720-482: 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 . 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
9900-407: Is strong when the factor of environmental selection is also introduced. Environmental selection may support a smaller chick size if those chicks were born in an area that allowed them to grow to a larger size, even though under normal conditions they would not be able to reach this optimal size for migration. When the environment gives advantages and disadvantages of this sort, the strength of selection
10080-504: Is the dragonet , in which males are considerably larger than females and possess longer fins. Sexual dimorphism also occurs in hermaphroditic fish. These species are known as sequential hermaphrodites . In fish, reproductive histories often include the sex-change from female to male where there is a strong connection between growth, the sex of an individual, and the mating system within which it operates. In protogynous mating systems where males dominate mating with many females, size plays
10260-509: Is the fifth heaviest living bird species, after only the larger varieties of ratite . The weight also varies by season, as both male and female penguins lose substantial mass while raising hatchlings and incubating their egg. Male emperor penguins must withstand the extreme Antarctic winter cold for more than two months while protecting their eggs; eating nothing during this time, male emperors will lose around 12 kg (26 lb) while waiting for their eggs to hatch. The mean weight of males at
10440-426: Is the only penguin species where this behaviour is observed; in all other penguin species both parents take shifts incubating. By the time the egg hatches, the male will have fasted for around 120 days since arriving at the colony. To survive the cold and savage winds of up to 200 km/h (120 mph), the males huddle together, taking turns in the middle of the huddle. They have also been observed with their backs to
10620-404: Is used by parents and chicks to locate one another in crowded colonies . Their eyes are adapted for underwater vision and are their primary means of locating prey and avoiding predators; in air it has been suggested that they are nearsighted , although research has not supported this hypothesis. Penguins have a thick layer of insulating feathers that keeps them warm in water (heat loss in water
10800-411: Is weakened and the environmental forces are given greater morphological weight. The sexual dimorphism could also produce a change in timing of migration leading to differences in mating success within the bird population. When the dimorphism produces that large of a variation between the sexes and between the members of the sexes, multiple evolutionary effects can take place. This timing could even lead to
10980-643: 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. Due to plate tectonics , these areas were at that time less than 1,500 kilometres (930 mi) apart rather than 4,000 kilometres (2,500 mi). The most recent common ancestor of penguins and Procellariiformes can be roughly dated to
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#173285158327511160-735: The Oxford English Dictionary , the American Heritage Dictionary , the Century Dictionary and Merriam-Webster , on the basis that the name was originally applied to the great auk, either because it was found on White Head Island ( Welsh : Pen Gwyn ) in Newfoundland, or because it had white circles around its eyes (though the head was black). However, the Welsh word pen can also be used to mean 'front' and, in
11340-659: The 66° and 77° south latitudes. It almost always breeds on stable pack ice near the coast and up to 18 km (11 mi) offshore. Breeding colonies are usually in areas where ice cliffs and icebergs provide some protection from the wind. Three land colonies have been reported: one (now disappeared) on a shingle spit at the Dion Islands on the Antarctic Peninsula , one on a headland at Taylor Glacier in Victoria Land , and most recently one at Amundsen Bay . Since 2009,
11520-402: 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
11700-581: The Campanian – Maastrichtian boundary, around 70–68 mya. The oldest known fossil penguin species is Waimanu manneringi , which lived 62 mya in New Zealand. While they were not as well-adapted to aquatic life as modern penguins, Waimanu were 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 from northern Peru
11880-661: 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 ), 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
12060-556: The Northern Hemisphere 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 , Breton or Spanish origin (the latter two are attributed to the French word pingouin ), but first appears in English or Dutch. Some dictionaries suggest a derivation from Welsh pen , 'head' and gwyn , 'white', including
12240-588: The Ross Sea shrank drastically between the first visits by the Discovery Expedition in 1902–03 and the later visits by the Terra Nova Expedition in 1910–11; it was reduced to a few hundred birds, and may have come close to extinction due to changes in the position of the ice shelf. By the 1960s it had rebounded dramatically, but by 2009 was again reduced to a small population of around 300. In 2012,
12420-480: The Terre Adélie region have been observed due to an increased death rate among adult birds, especially males, during an abnormally prolonged warm period in the late 1970s, which resulted in reduced sea-ice coverage. On the other hand, egg hatching success rates declined when the sea-ice extent increased; chick deaths also increased; the species is therefore considered to be highly sensitive to climatic changes. In 2009,
12600-533: The auricular patches, chin and throat are white, while its bill is black. Emperor penguin chicks are typically covered with silver-grey down and have black heads and white masks. A chick with all-white plumage was seen in 2001, but was not considered to be an albino as it did not have pink eyes. Chicks weigh around 315 g (11.1 oz) after hatching, and fledge when they reach about 50% of adult weight. The emperor penguin's dark plumage fades to brown from November until February (the Antarctic summer), before
12780-604: The blue-footed booby , the female chicks grow faster than the males, resulting in booby parents producing the smaller sex, the males, during times of food shortage. This then results in the maximization of parental lifetime reproductive success. In Black-tailed Godwits Limosa limosa limosa females are also the larger sex, and the growth rates of female chicks are more susceptible to limited environmental conditions. Sexual dimorphism may also only appear during mating season; some species of birds only show dimorphic traits in seasonal variation. The males of these species will molt into
12960-700: The family Spheniscidae ( / s f ɪ ˈ n ɪ s ɪ d iː , - d aɪ / ) of the order Sphenisciformes ( / s f ɪ ˈ n ɪ s ə f ɔːr m iː z / ). They live almost exclusively in the Southern Hemisphere : only one species , the Galápagos penguin , is found north of the Equator . Highly adapted for life in the ocean water, penguins have countershaded dark and white plumage and flippers for swimming. Most penguins feed on krill , fish , squid and other forms of sea life which they catch with their bills and swallow whole while swimming. A penguin has
13140-489: The ovules ). Each pollen grain accordingly may be seen as a male plant in its own right; it produces a sperm cell and is dramatically different from the female plant, the megagametophyte that produces the female gamete. Insects display a wide variety of sexual dimorphism between taxa including size, ornamentation and coloration. The female-biased sexual size dimorphism observed in many taxa evolved despite intense male-male competition for mates. In Osmia rufa , for example,
13320-489: 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
13500-573: 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
13680-407: The 'fittest' available male. Sexual dimorphism is a product of both genetics and environmental factors. An example of sexual polymorphism determined by environmental conditions exists in the red-backed fairywren . Red-backed fairywren males can be classified into three categories during breeding season : black breeders, brown breeders, and brown auxiliaries. These differences arise in response to
13860-408: The 1960s, keeping attempts were largely unsuccessful, as knowledge of penguin keeping in general was limited and acquired by trial and error. The first to achieve a level of success was Aalborg Zoo where a chilled house was built especially for this Antarctic species. One individual lived for 20 years at the zoo and a chick was hatched there, but died shortly after. Today, the species is kept at just
14040-502: The Antarctic and sub-Antarctic; around 35% of the known population lives north of the Antarctic Circle . Major breeding colonies were located at Cape Washington , Coulman Island in Victoria Land , Halley Bay , Cape Colbeck , and Dibble Glacier . Colonies are known to fluctuate over time, often breaking into "suburbs" which move apart from the parent group, and some have been known to disappear entirely. The Cape Crozier colony on
14220-574: The Dion Islands colony, which had been extensively studied since 1948, was reported to have completely disappeared at some point over the previous decade, the fate of the birds unknown. This was the first confirmed loss of an entire colony. Beginning in September 2015, a strong El Niño , strong winds, and record low amounts of sea ice resulted in "almost total breeding failure" with the deaths of thousands of emperor chicks for three consecutive years within
14400-502: The Emperor penguins by 5 to 10 percent to around 278,000 breeding pairs. Given their remote locations and harsh weather conditions, penguin populations are found by scanning aerial imagery and locating enormous pages of ice that have been stained with their guano . The new discoveries increased the number of known breeding sites from 50 to 61. The penguins start courtship in March or April, when
14580-526: The Halley Bay colony, the second largest emperor penguin colony in the world. Researchers have attributed this loss to immigration of breeding penguins to the Dawson-Lambton colony 55 km (34 mi) south, in which a tenfold population increase was observed between 2016 and 2018. However, this increase is nowhere near the total number of breeding adults formerly at the Halley Bay colony. In January 2009,
14760-514: The Middle Miocene ( Langhian , roughly 15–14 mya), although 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. The geographical and temporal pattern of spheniscine evolution corresponds closely to two episodes of global cooling documented in the paleoclimatic record . The emergence of
14940-527: 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
15120-665: 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. The genera Spheniscus and Eudyptula contain species with
15300-530: 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
15480-578: The Woods Hole Oceanographic Institution in 2014 again concluded that emperor penguins are at risk from global warming, which is melting the sea ice. This study predicted that by 2100 all 45 colonies of emperor penguins will be declining in numbers, mostly due to loss of habitat. Loss of ice reduces the supply of krill , which is a primary food for emperor penguins. In December 2022, a new colony at Verleger Point in West Antarctica
15660-410: The ability to reduce its metabolism and shut down non-essential organ functions. The only penguin species that breeds during the Antarctic winter, emperor penguins trek 50–120 km (31–75 mi) over the ice to breeding colonies which can contain up to several thousand individuals. The female lays a single egg, which is incubated for just over two months by the male while the female returns to
15840-415: The adults and their chicks. All orphaned chicks will rapidly become weaker and die of starvation, or freeze to death. About 45–50 days after hatching, the chicks form a crèche , huddling together for warmth and protection. During this time, both parents forage at sea and return periodically to feed their chicks. A crèche may consist of around a dozen, up to several thousand chicks densely packed together and
16020-533: 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
16200-533: The bird's body condition: if they are healthy they will produce more androgens thus becoming black breeders, while less healthy birds produce less androgens and become brown auxiliaries. The reproductive success of the male is thus determined by his success during each year's non-breeding season, causing reproductive success to vary with each year's environmental conditions. Migratory patterns and behaviors also influence sexual dimorphisms. This aspect also stems back to size dimorphism in species. It has been shown that
16380-995: The body. For example, in sockeye salmon , males develop larger body size at maturity, including an increase in body depth, hump height, and snout length. Females experience minor changes in snout length, but the most noticeable difference is the huge increase in gonad size, which accounts for about 25% of body mass. Sexual selection was observed for female ornamentation in Gobiusculus flavescens , known as two-spotted gobies. Traditional hypotheses suggest that male–male competition drives selection. However, selection for ornamentation within this species suggests that showy female traits can be selected through either female–female competition or male mate choice. Since carotenoid-based ornamentation suggests mate quality, female two-spotted guppies that develop colorful orange bellies during breeding season are considered favorable to males. The males invest heavily in offspring during incubation, which leads to
16560-470: The caudal chevrons of male crocodiles, used to anchor the penis muscles, were significantly larger than those of females. There have been criticisms of these findings, but it remains a subject of debate among advocates and adversaries. Ornithopoda Studies of sexual dimorphism in hadrosaurs have generally centered on the distinctive cranial crests , which likely provided a function in sexual display. A biometric study of 36 skulls found sexual dimorphism
16740-572: The chick or reclaim it, if it has been successfully stolen. These scuffles involving several birds often result in the chick being smothered or trampled to death. Chicks which have been adopted or stolen are quickly abandoned once again, as it is impossible for the female to feed and care for the chick alone. The orphaned chicks wander around the colony attempting to seek food and protection from other adults. They will even try to shelter themselves in an adult bird's brood patch already occupied by their own chick. These stray chicks are brusquely driven away by
16920-410: The chick, feeding it by regurgitating the partially digested fish, squid and krill that she has stored in her stomach. The male is often reluctant to surrender the chick he has been caring for all winter to its mother, but he soon leaves to take his turn at sea, spending 3 to 4 weeks feeding there before returning. The parents then take turns, one brooding while the other forages at sea. If either parent
17100-414: The chick. If the mother penguin is delayed, the chick will die. The young chick is brooded in what is called the guard phase , spending time balanced on its parent's feet and kept warm by the brood patch. The female penguin returns at any time from hatching up to ten days afterwards, from mid-July to early August. She finds her mate among the hundreds of fathers by his vocal call and takes over caring for
17280-421: 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
17460-416: The cold, the emperor penguin encounters another stressful condition on deep dives—markedly increased pressure of up to 40 times that of the surface, which in most other terrestrial organisms would cause barotrauma . The bones of the penguin are solid rather than air-filled, which eliminates the risk of mechanical barotrauma. While diving, the emperor penguin's oxygen use is markedly reduced, as its heart rate
17640-408: The colony next year to try mating again. After a successful transfer of the egg to the male penguin, the female departs for the sea and the male spends the dark, stormy winter incubating the egg against his brood patch , a patch of skin without feathers. There he balances it on the tops of his feet, engulfing it with loose skin and feathers for around 65-75 consecutive days until hatching. The emperor
17820-503: The colony together, with the female usually following the male. Before copulation , one bird bows deeply to its mate, its bill pointed close to the ground, and its mate then does the same. Contrary to popular belief, Emperor penguins do not mate for life; they are serially monogamous , having only one mate each year, and remaining faithful to that mate. However, fidelity between years is only around 15%. The narrow window of opportunity available for mating appears to be an influence, as there
18000-400: The costs and evolutionary implications vary from species to species. The peafowl constitute conspicuous illustrations of the principle. The ornate plumage of peacocks, as used in the courting display, attracts peahens . At first sight, one might mistake peacocks and peahens for completely different species because of the vibrant colours and the sheer size of the male's plumage; the peahen
18180-499: The crustacean and fish populations. Other reasons for the species's placement on the Endangered Species Act's list include disease, habitat destruction , and disturbance at breeding colonies by humans. Of particular concern is the impact of tourism. One study concluded that emperor penguin chicks in a crèche become more apprehensive following a helicopter approach to 1,000 m (3,300 ft). Population declines of 50% in
18360-654: The degree of preservation. The availability of well-preserved remains is not a probable outcome as a consequence of decomposition and fossilization . Some paleontologists have looked for sexual dimorphism among dinosaurs using statistics and comparison to ecologically or phylogenetically related modern animals. Apatosaurus and Diplodocus Female Apatosaurus and Diplodocus had interconnected caudal vertebrae that allowed them to keep their tails elevated to aid in copulation. Discovering that this fusion occurred in only 50% of Apatosaurus and Diplodocus skeletons and 25% of Camarasaurus skeletons indicated that this
18540-425: The edge of the pack ice. The start of travel appears to be triggered by decreasing day lengths; emperor penguins in captivity have been induced successfully into breeding by using artificial lighting systems mimicking seasonal Antarctic day lengths. The British Antarctic Survey (BAS) used satellite imagery to find new Emperor penguin breeding sites in Antarctica, a discovery that increased the estimated population of
18720-412: The egg can be awkward and difficult, especially for first-time parents, and many couples drop or crack the egg in the process. When this happens, the chick inside is quickly lost, as the egg cannot withstand the sub-freezing temperatures on the icy ground for more than one to two minutes. When a couple loses an egg in this manner, their relationship is ended and both walk back to the sea. They will return to
18900-517: The emergence of another morphotype in the same area, the similarly sized but more gracile Palaeospheniscinae , as well as the radiation that gave rise to the current biodiversity of 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 , 19 high-coverage genomes that, together with two previously published genomes, encompass all extant penguin species have been sequenced. The origin of
19080-545: The emperor is flightless, with a streamlined body, and wings stiffened and flattened into flippers for a marine habitat . Its diet consists primarily of fish , but also includes crustaceans , such as krill , and cephalopods , such as squid . While hunting, the species can remain submerged around 20 minutes, diving to a depth of 535 m (1,755 ft). It has several adaptations to facilitate this, including an unusually structured haemoglobin to allow it to function at low oxygen levels, solid bones to reduce barotrauma , and
19260-401: The emperor penguin alternates between walking with a wobbling gait and tobogganing—sliding over the ice on its belly, propelled by its feet and wing-like flippers. Like all penguins, it is flightless. The emperor penguin is a very powerful bird. In one case, a crew of six men, trying to capture a single male penguin for a zoo collection, were repeatedly tossed around and knocked over before all of
19440-516: The emperor penguin population comprises adults five years and older. As the species has no fixed nesting sites that individuals can use to locate their own partner or chick, emperor penguins must rely on vocal sounds alone for identification. They use a complex set of calls that are critical to individual recognition between mates, parents and offspring, displaying the widest variation in individual calls of all penguin species. Vocalizing emperor penguins use two frequency bands simultaneously. Chicks use
19620-514: The emperor penguin was downgraded from a species of least concern to near threatened by the IUCN . Along with nine other species of penguin, it is currently under consideration for inclusion under the US Endangered Species Act . The primary causes for an increased risk of species endangerment are declining food availability, due to the effects of climate change and industrial fisheries on
19800-448: The empty shells. If she grows too large, she will not fit in the shells and will be unable to breed. The female's small body size is also likely beneficial to her chances of finding an unoccupied shell. Larger shells, although preferred by females, are often limited in availability. Hence, the female is limited to the growth of the size of the shell and may actually change her growth rate according to shell size availability. In other words,
19980-581: The end of the Paleogene , around 25 mya. Their decline and disappearance coincided with the spread of the Squalodontidae and other primitive, fish-eating toothed whales , which competed with them for food and were ultimately more successful. A new lineage, the Paraptenodytes , which includes smaller and stout-legged forms, had already arisen in southernmost South America by that time. The early Neogene saw
20160-510: The estrogen pathway. The sexual dimorphism in lizards is generally attributed to the effects of sexual selection, but other mechanisms including ecological divergence and fecundity selection provide alternative explanations. The development of color dimorphism in lizards is induced by hormonal changes at the onset of sexual maturity, as seen in Psamodromus algirus , Sceloporus gadoviae , and S. undulates erythrocheilus . Sexual dimorphism in size
20340-402: The exception is the little penguin, which can raise two or three broods in a season. Penguin eggs are smaller than any other bird species when compared proportionally to the weight of the parent birds; at 52 g (2 oz), the little penguin egg is 4.7% of its mothers' weight, and the 450 g (1 lb) emperor penguin egg is 2.3%. The relatively thick shell forms between 10 and 16% of
20520-443: The exhausted anthers after a day or two and perhaps change their colours as well while the pistil matures; specialist pollinators are very much inclined to concentrate on the exact appearance of the flowers they serve, which saves their time and effort and serves the interests of the plant accordingly. Some such plants go even further and change their appearance once fertilized, thereby discouraging further visits from pollinators. This
20700-475: 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
20880-463: 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 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
21060-442: The fairy penguin, which stands around 30–33 cm (12–13 in) tall and weighs 1.2–1.3 kg (2.6–2.9 lb). Today, larger penguins generally inhabit colder regions, and smaller penguins inhabit regions with temperate or tropical climates . Some prehistoric penguin species were enormous: as tall or heavy as an adult human. There was a great diversity of species in subantarctic regions, and at least one giant species in
21240-400: The family of the auks (Alcidae), within the order of the Charadriiformes . 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
21420-417: The female is larger/broader than males, with males being 8–10 mm in size and females being 10–12 mm in size. In the hackberry emperor females are similarly larger than males. The reason for the sexual dimorphism is due to provision size mass, in which females consume more pollen than males. In some species, there is evidence of male dimorphism, but it appears to be for distinctions of roles. This
21600-564: The female, which looks different from the males. Various other dioecious exceptions, such as Loxostylis alata have visibly different sexes, with the effect of eliciting the most efficient behavior from pollinators, who then use the most efficient strategy in visiting each gender of flower instead of searching, say, for pollen in a nectar-bearing female flower. Some plants, such as some species of Geranium have what amounts to serial sexual dimorphism. The flowers of such species might, for example, present their anthers on opening, then shed
21780-651: The form of reduced survival. This means that even if the trait causes males to die earlier, the trait is still beneficial so long as males with the trait produce more offspring than males lacking the trait. This balance keeps dimorphism alive in these species and ensures that the next generation of successful males will also display these traits that are attractive to females. Such differences in form and reproductive roles often cause differences in behavior. As previously stated, males and females often have different roles in reproduction. The courtship and mating behavior of males and females are regulated largely by hormones throughout
21960-723: The fossil record. Stegosaurians A 2015 study on specimens of Hesperosaurus mjosi found evidence of sexual dimorphism in the shape of the dermal plates. Two plate morphs were described: one was short, wide, and oval-shaped, the other taller and narrower. In a large proportion of mammal species, males are larger than females. Both genes and hormones affect the formation of many animal brains before " birth " (or hatching ), and also behaviour of adult individuals. Hormones significantly affect human brain formation, and also brain development at puberty. A 2004 review in Nature Reviews Neuroscience observed that "because it
22140-700: The head or thorax expressed only in the males. Copris ochus also has distinct sexual and male dimorphism in head horns. Another beetle with a distinct horn-related sexual dimorphism is Allomyrina dichotoma, also known as the Japanese rhinoceros beetle . These structures are impressive because of the exaggerated sizes. There is a direct correlation between male horn lengths and body size and higher access to mates and fitness. In other beetle species, both males and females may have ornamentation such as horns. Generally, insect sexual size dimorphism (SSD) within species increases with body size. Sexual dimorphism within insects
22320-420: The head, chin, throat, back, dorsal part of the flippers, and tail. The black plumage is sharply delineated from the light-coloured plumage elsewhere. The underparts of the wings and belly are white, becoming pale yellow in the upper breast, while the ear patches are bright yellow. The upper mandible of the 8 cm (3.1 in) long bill is black, and the lower mandible can be pink, orange or lilac. In juveniles,
22500-409: The king penguin, the emperor penguin is one of two extant species in the genus Aptenodytes . Fossil evidence of a third species— Ridgen's penguin ( A. ridgeni )—has been found in fossil records from the late Pliocene , about three million years ago, in New Zealand. Studies of penguin behaviour and genetics have proposed that the genus Aptenodytes is basal ; in other words, that it split off from
22680-444: The larger males are better at coping with the difficulties of migration and thus are more successful in reproducing when reaching the breeding destination. When viewing this from an evolutionary standpoint, many theories and explanations come into consideration. If these are the result for every migration and breeding season, the expected results should be a shift towards a larger male population through sexual selection. Sexual selection
22860-476: The live chicks are usually too large to be attacked by the time of its annual arrival in the colony. Occasionally, a parent may attempt to defend its chick from attack, although it may be more passive if the chick is weak or sickly. The only known predators thought to attack healthy adults, and which attack emperor penguins in the water, are both mammals. The first is the leopard seal ( Hydrurga leptonyx ), which takes adult birds and fledglings soon after they enter
23040-414: 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
23220-508: The male's ability to collect large shells depends on his size. The larger the male, the larger the shells he is able to collect. This then allows for females to be larger in his brooding nest which makes the difference between the sizes of the sexes less substantial. Male–male competition in this fish species also selects for large size in males. There is aggressive competition by males over territory and access to larger shells. Large males win fights and steal shells from competitors. Another example
23400-429: The men had to collectively tackle the bird, which weighs about half as much as a man. As a defence against the cold, a colony of emperor penguins forms a compact huddle (also known as the turtle formation) ranging in size from ten to several hundred birds, with each bird leaning forward on a neighbour. As the wind chill is the least severe in the center of the colony, all the juveniles are usually huddled there. Those on
23580-593: The more ornamented or brightly colored sex. Such differences have been attributed to the unequal reproductive contributions of the sexes. This difference produces a stronger female choice since they have more risk in producing offspring. In some species, the male's contribution to reproduction ends at copulation, while in other species the male becomes the main (or only) caregiver. Plumage polymorphisms have evolved to reflect these differences and other measures of reproductive fitness, such as body condition or survival. The male phenotype sends signals to females who then choose
23760-692: The most common causes for mortality in young fish. Most flowering plants are hermaphroditic but approximately 6% of species have separate males and females ( dioecy ). Sexual dimorphism is common in dioecious plants and dioicous species. Males and females in insect-pollinated species generally look similar to one another because plants provide rewards (e.g. nectar ) that encourage pollinators to visit another similar flower , completing pollination . Catasetum orchids are one interesting exception to this rule. Male Catasetum orchids violently attach pollinia to euglossine bee pollinators. The bees will then avoid other male flowers but may visit
23940-459: The most important food source, and the Antarctic silverfish ( Pleuragramma antarcticum ) makes up the bulk of the bird's diet. Other prey commonly recorded include other fish of the family Nototheniidae , the glacial squid ( Psychroteuthis glacialis ), and the hooked squid species Kondakovia longimana , as well as Antarctic krill ( Euphausia superba ). The emperor penguin searches for prey in
24120-607: 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. Penguins form monogamous pairs for
24300-448: The mother's return, and the father feeds it a curd -like substance composed of 59% protein and 28% lipid , which is produced by a gland in his oesophagus . This ability to produce " crop milk " in birds is only found in pigeons, flamingos and male Emperor penguins. The father is able to produce this crop milk to temporarily sustain the chick for generally 4 to 7 days, until the mother returns from fishing at sea with food to properly feed
24480-477: The open water of the Southern Ocean , in either ice-free areas of open water or tidal cracks in pack ice. One of its feeding strategies is to dive to around 50 m (160 ft), where it can easily spot sympagic fish like the bald notothen ( Pagothenia borchgrevinki ) swimming against the bottom surface of the sea-ice; it swims up to the bottom of the ice and catches the fish. It then dives again and repeats
24660-564: The outside upwind tend to shuffle slowly around the edge of the formation and add themselves to its leeward edge, producing a slow churning action, and giving each bird a turn on the inside and on the outside. The emperor penguin's predators include birds and aquatic mammals. Southern giant petrels ( Macronectes giganteus ) are the predominant land predator of chicks, responsible for over one-third of chick deaths in some colonies; they also scavenge dead penguins. The south polar skua ( Stercorarius maccormicki ) mainly scavenges for dead chicks, as
24840-637: The palaeeudyptines constitute a monophyletic lineage, or whether gigantism was evolved independently in a restricted Palaeeudyptinae and the Anthropornithinae – whether they were considered valid, or whether there was a wide size range present in the Palaeeudyptinae as delimited (i.e., including Anthropornis nordenskjoeldi ). The oldest well-described giant penguin, the 5-foot (1.5 m)-tall Icadyptes salasi , existed as far north as northern Peru about 36 mya. Gigantic penguins had disappeared by
25020-466: The penguin-like 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
25200-408: The penguins, but are an example of convergent evolution . 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. Penguins for
25380-594: 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 . Penguins are superbly adapted to aquatic life. Their wings have evolved to become flippers, useless for flight in
25560-400: The placement of the penguins in the avian phylogeny is presently resolved, this is confusing, so the established Linnean system is followed here. The number of penguin species is typically listed as between seventeen and nineteen. The International Ornithologists' Union recognizes six genera and eighteen species: Although the evolutionary and biogeographic history of Sphenisciformes
25740-436: The plants become sexually mature. Every sexually reproducing extant species of the vascular plant has an alternation of generations; the plants we see about us generally are diploid sporophytes , but their offspring are not the seeds that people commonly recognize as the new generation. The seed actually is the offspring of the haploid generation of microgametophytes ( pollen ) and megagametophytes (the embryo sacs in
25920-418: The presence of specific sex-related behaviour is common to many lizards; and vocal qualities which are frequently observed in frogs . Anole lizards show prominent size dimorphism with males typically being significantly larger than females. For instance, the average male Anolis sagrei was 53.4 mm vs. 40 mm in females. Different sizes of the heads in anoles have been explained by differences in
26100-410: The principle. There are two types of dichromatism for frog species: ontogenetic and dynamic. Ontogenetic frogs are more common and have permanent color changes in males or females. Ranoidea lesueuri is an example of a dynamic frog with temporary color changes in males during the breeding season. Hyperolius ocellatus is an ontogenetic frog with dramatic differences in both color and pattern between
26280-408: The production of more exaggerated ornaments in males may come at the cost of suppressed immune function. So long as the reproductive benefits of the trait due to sexual selection are greater than the costs imposed by natural selection, then the trait will propagate throughout the population. Reproductive benefits arise in the form of a larger number of offspring, while natural selection imposes costs in
26460-514: 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 . 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 σφήν sphēn " wedge " used for the shape of an African penguin 's swimming flippers. Some recent sources apply
26640-585: The same plumage pattern, though the female is clearly distinguishable by reason of her paler or washed-out colour". Examples include Cape sparrow ( Passer melanurus ), rufous sparrow (subspecies P. motinensis motinensis ), and saxaul sparrow ( P. ammodendri ). Examining fossils of non-avian dinosaurs in search of sexually dimorphic characteristics requires the supply of complete and articulated skeletal and tissue remains. As terrestrial organisms, dinosaur carcasses are subject to ecological and geographical influence that inevitably constitutes
26820-405: The sea after incubation heads directly out to areas of permanent open water, known as polynyas , around 100 km (62 mi) from the colony. An efficient swimmer, the emperor penguin exerts pressure with both its upward and downward strokes while swimming. The upward stroke works against buoyancy and helps maintain depth. Its average swimming speed is 6–9 km/h (3.7–5.6 mph). On land,
27000-492: The sea to feed; parents subsequently take turns foraging at sea and caring for their chick in the colony. The lifespan of an emperor penguin is typically 20 years in the wild, although observations suggest that some individuals may live as long as 50 years of age. Emperor penguins were described in 1844 by English zoologist George Robert Gray , who created the generic name from Ancient Greek word elements, ἀ-πτηνο-δύτης [a-ptēno-dytēs], "without-wings-diver". Its specific name
27180-552: The sequence about half a dozen times before surfacing to breathe . Since the 1930s, there have been several attempts at keeping emperor penguins in captivity. Malcolm Davis of the National Zoological Park made early attempts at keeping penguins, capturing several from Antarctica. He successfully transferred penguins to the National Zoological Park on March 5, 1940, where they lived for up to 6 years. Until
27360-479: The sexes, and allometry, but their relative importance is still not fully understood . Sexual dimorphism in birds can be manifested in size or plumage differences between the sexes. Sexual size dimorphism varies among taxa, with males typically being larger, though this is not always the case, e.g. birds of prey , hummingbirds , and some species of flightless birds. Plumage dimorphism, in the form of ornamentation or coloration, also varies, though males are typically
27540-526: The sexes. At sexual maturity, the males display a bright green with white dorsolateral lines. In contrast, the females are rusty red to silver with small spots. The bright coloration in the male population attracts females and is an aposematic sign to potential predators. Females often show a preference for exaggerated male secondary sexual characteristics in mate selection. The sexy son hypothesis explains that females prefer more elaborate males and select against males that are dull in color, independent of
27720-511: The sexual preference in colorful females due to higher egg quality. In amphibians and reptiles, the degree of sexual dimorphism varies widely among taxonomic groups . The sexual dimorphism in amphibians and reptiles may be reflected in any of the following: anatomy; relative length of tail; relative size of head; overall size as in many species of vipers and lizards ; coloration as in many amphibians , snakes , and lizards, as well as in some turtles ; an ornament as in many newts and lizards;
27900-414: The size dimorphic wolf spider Tigrosa helluo , food-limited females cannibalize more frequently. Therefore, there is a high risk of low fitness for males due to pre-copulatory cannibalism, which led to male selection of larger females for two reasons: higher fecundity and lower rates of cannibalism. In addition, female fecundity is positively correlated with female body size and large female body size
28080-748: The skin. Conversely, the plumage is flattened in water, thus waterproofing the skin and the downy underlayer. Preening is vital in facilitating insulation and in keeping the plumage oily and water-repellent. The emperor penguin is able to thermoregulate (maintain its core body temperature) without altering its metabolism, over a wide range of temperatures. Known as the thermoneutral range, this extends from −10 to 20 °C (14 to 68 °F). Below this temperature range, its metabolic rate increases significantly, although an individual can maintain its core temperature from 38.0 °C (100.4 °F) down to −47 °C (−53 °F). Movement by swimming, walking, and shivering are three mechanisms for increasing metabolism;
28260-424: The smallest eggs relative to the maternal weight in any bird species. 15.7% of the weight of an emperor penguin egg is shell; like those of other penguin species, the shell is relatively thick, which helps minimize risk of breakage. After laying, the mother's food reserves are exhausted and she very carefully transfers the egg to the male, and then immediately returns to the sea for two months to feed. The transfer of
28440-567: The species' vision. Similar sexual dimorphism and mating choice are also observed in many fish species. For example, male guppies have colorful spots and ornamentations, while females are generally grey. Female guppies prefer brightly colored males to duller males. In redlip blennies , only the male fish develops an organ at the anal-urogenital region that produces antimicrobial substances. During parental care, males rub their anal-urogenital regions over their nests' internal surfaces, thereby protecting their eggs from microbial infections, one of
28620-539: The start of the breeding season is 38 kg (84 lb) and that of females is 29.5 kg (65 lb). After the breeding season this drops to 23 kg (51 lb) for both sexes. Like all penguin species, emperor penguins have streamlined bodies to minimize drag while swimming, and wings that are more like stiff, flat flippers. The tongue is equipped with rear-facing barbs to prevent prey from escaping when caught. Males and females are similar in size and colouration. The adult has deep black dorsal feathers, covering
28800-537: 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 for paleognaths and fowl ) that comprises what
28980-641: 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 for birds; this
29160-465: The temperature can be as low as −40 °C (−40 °F). A lone male gives an ecstatic display, where it stands still and places its head on its chest before inhaling and giving a courtship call for 1–2 seconds; it then moves around the colony and repeats the call. A male and female then stand face to face, with one extending its head and neck up and the other mirroring it; they both hold this posture for several minutes. Once in pairs, couples waddle around
29340-537: The thousands of free-floating flowers released by a male. Sexual dimorphism is most often associated with wind-pollination in plants due to selection for efficient pollen dispersal in males vs pollen capture in females, e.g. Leucadendron rubrum . Sexual dimorphism in plants can also be dependent on reproductive development. This can be seen in Cannabis sativa , a type of hemp, which have higher photosynthesis rates in males while growing but higher rates in females once
29520-545: 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
29700-657: 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 . Sexual dimorphism Sexual dimorphism is the condition where sexes of the same species exhibit different morphological characteristics, including characteristics not directly involved in reproduction . The condition occurs in most dioecious species, which consist of most animals and some plants. Differences may include secondary sex characteristics , size, weight, color, markings, or behavioral or cognitive traits. Male-male reproductive competition has evolved
29880-487: The water. Orcas ( Orcinus orca ), mostly take adult birds, although they will attack penguins of any age in or near water. Although Emperor penguins can breed at around three years of age, they generally do not begin breeding for another one to three years. The yearly reproductive cycle begins at the start of the Antarctic winter, in March and April, when all mature emperor penguins travel to colonial nesting areas, often walking 50 to 120 km (31 to 75 mi) inland from
30060-491: 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. When emperor penguin mothers lose a chick, they sometimes attempt to "steal" another mother's chick, usually unsuccessfully as other females in
30240-454: The whinchat in Switzerland breed in intensely managed grasslands. Earlier harvesting of the grasses during the breeding season lead to more female deaths. Populations of many birds are often male-skewed and when sexual differences in behavior increase this ratio, populations decline at a more rapid rate. Also not all male dimorphic traits are due to hormones like testosterone, instead they are
30420-472: The wind to conserve body heat. In the four months of travel, courtship, and incubation, the male may lose as much as 20 kg (44 lb), from a total mass of 38 to 18 kg (84 to 40 lb). Hatching may take as long as two or three days to complete, as the shell of the egg is thick. Newly hatched chicks are semi-altricial , covered with only a thin layer of down and entirely dependent on their parents for food and warmth. The chick usually hatches before
30600-462: The year between the breeding colony and ocean foraging areas; the species disperses into the oceans from January to March. The American physiologist Gerry Kooyman revolutionised the study of penguin foraging behaviour in 1971 when he published his results from attaching automatic dive-recording devices to emperor penguins. He found that the species reaches depths of 265 m (869 ft), with dive periods of up to 18 minutes. Later research revealed
30780-760: The yearly moult in January and February. Moulting is rapid in this species compared with other birds, taking only around 34 days. Emperor penguin feathers emerge from the skin after they have grown to a third of their total length, and before old feathers are lost, to help reduce heat loss. New feathers then push out the old ones before finishing their growth. The average yearly survival rate of an adult emperor penguin has been measured at 95.1%, with an average life expectancy of 19.9 years. The same researchers estimated that 1% of emperor penguins hatched could feasibly reach an age of 50 years. In contrast, only 19% of chicks survive their first year of life. Therefore, 80% of
30960-696: Was also released with the English title March of the Penguins , told the story of the penguins' reproductive cycle. The subject has been covered for the small screen five times by the BBC and presenter David Attenborough : first in episode five of the 1993 series on the Antarctic Life in the Freezer , again in the 2001 series The Blue Planet , once again in the 2006 series Planet Earth , in Frozen Planet in 2011 and
31140-417: 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
31320-627: 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. 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 (5.9 feet) tall. The New Zealand giant penguin
31500-509: Was discovered by satellite imaging, bringing the total known colonies to 66. In 2023, another study found that more than 90% of emperor penguin colonies could face "quasi-extinction" from "catastrophic breeding failure" due to the loss of sea ice caused by climate change. The emperor penguin is a social animal in its nesting and its foraging behaviour; birds hunting together may coordinate their diving and surfacing. Individuals may be active day or night. A mature adult travels throughout most of
31680-696: 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. Penguin ancestry beyond Waimanu remains unknown and not well-resolved by molecular or morphological analyses. The latter tend to be confounded by
31860-470: Was exhibited in the crest of 3 species of hadrosaurids. The crests could be categorized as full (male) or narrow (female) and may have given some advantage in intrasexual mating-competition. Ceratopsians According to Scott D. Sampson, if ceratopsids were to exhibit sexual dimorphism, modern ecological analogues suggest it would be found in display structures, such as horns and frills. No convincing evidence for sexual dimorphism in body size or mating signals
32040-633: Was in Denmark, Western Australia in November 2024. This individual, which is believed to have originated from eastern Antarctica, was encountered by a group of surfers shortly after it arrived in Denmark, and was taken in by conservationists at the Department of Biodiversity, Conservation and Attractions to have its condition evaluated. In 2009, the total population of emperor penguins was estimated to be at around 595,000 adult birds, in 46 known colonies spread around
32220-601: Was probably the heaviest, weighing 80 kilograms (180 lb) 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 two major extinct lineages. One or two closely related ones occurred in Patagonia , and at least one other—which
32400-403: Was suggestive of feeding near or at the sea bottom. In 1994, a penguin from Auster rookery reached a depth of 564 m (1,850 ft); the entire dive took him 21.8 min. Both male and female emperor penguins forage for food up to 500 km (310 mi) from colonies while collecting food to feed chicks, covering 82–1,454 km (51–903 mi) per individual per trip. A male returning to
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