he Penguins (Spheniscidae) are a group of flightless birds of the southern hemisphere and are the only family in the order Sphenisciformes. Your phylogenetic sister group probably form the loons (Gaviiformes) and Procellariiformes (Procellariiformes). Penguins are easily distinguished from all other birds, and in an outstanding way to life in the seaand adapted to the sometimes extreme cold zones of the earth.
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[ Show ]Etymology
The German name penguin comes directly from the English word penguin from and is probably derived from Welsh pen gwyn "white head" her. However, penguins do not have white heads, and the name penguin originally referred to the indigenous to the northern hemisphere in the Atlantic, now extinct flightless Great Auk (formerly Pinguinus impennis ), in which the wings were also modified into fins. Although not closely related to this, the name of seafarers was transferred to the superficially similar-looking penguins.
Anatomy and appearance
The size and weight difference of the various penguin species is considerable, physique and feathers are in the family, however, very homogeneous.
Size and weight
The Little Penguin ( Eudyptula minor ) only reaches a size of 30 centimeters and a weight of one to one and a half kilograms, whereas the part of the Emperor Penguin (Aptenodytes forsteri ) with a size of up to 1.20 meters and weighing up to 40 kilograms to the Neukiefervögeln largest ever. This size difference is due to the Bergmann's rule states for which the Penguins are a commonly cited example. Bergmann's rule states that animals are larger in colder regions, since this leads to a more favorable ratio of volume to surface area of the animal and thus less heat loss. Most species are only a little lighter than the water displaced by them, so that they fall diving comparatively easy.
Physique
The sturdy-looking body of animals is by its streamlined shape significantly adapted and redesigned to narrow but strong wing fins to life in the sea. Unlike the also flightless ratitespenguins have a sternum with highly trained keel on which attaches the strong wing muscles. Because unlike when flying in air while swimming under water because of the higher water resistance of the wing boom as much energy costs the same as the wing downturn that have shoulder blades an enlarged compared to other birds surface, which creates the opportunities the organization responsible for the recovery muscles. Upper and lower arm bones are straight and rigidly connected to each other at the elbow, giving the fins a great strength. The birds usually hollow bones are dense and difficult at penguins, as a weight reduction to swim is not necessary.
The thighs are very short, the knee joint is rigid and the legs strong offset to the rear, which is caused in the land of unusual upright gait. The webbed big feet are relatively short - on land, the animals often rest on their heels, with their comparatively rigid tail feathers provide an additional support. The tail is usually greatly reduced, his other diving seabirds much steeper function as a rudder is taken primarily from the legs.
The beak is not very long in most species, but strong, except for the big penguins ( Aptenodytes ), whose beak probably in adaptation to its prey - is long, slender and slightly curved downward - fast swimming fish.
Thermoregulatory
Penguins are exposed to in their habitat sometimes extreme climatic conditions and have it customized by different anatomical features.
For heat insulation initially serves a distinct, often two to three centimeters thick layer of fat over the three waterproof layers are short, densely packed and evenly over the entire body of distributed springs. Apterien , skin regions where no feathers grow, there are at penguins in Unlike almost all other birds not, except for in some tropical species the facial skin. The trapped air in the spring layers protects the water is also very effective against heat loss.
In addition, penguins have sophisticated heat exchangers in their fins and legs: The water flowing into these limbs arterial blood gives up its heat to a large extent on the cooler flowing back into the body venous blood, so that heat losses are minimized. This is known as "counter-current".
On the other hand, some native to tropical waters penguin species rather fight with overheating. Is to prevent this, their fins are widened in comparison with the height, so that the surface can be discharged via the heat, expands. In some species, the facial skin is not of springs is also covered so that pent-up heat can be dissipated more rapidly in actively visited shadows. Some penguin species are shifting their activity time even completely on the evening or the night.
Plumage
The color of the of numerous small, undifferentiated, almost hair-like feathers existing plumage is at the back of almost all kinds, a bull's eye playing blue-gray, ventral side on the other hand knows. Males and females look very similar, although the former are usually somewhat larger. A particularly striking orange-yellow headdress stands out most macaroni penguins ( Eudyptesoff).
In young animals, the plumage is mostly uniform gray to brown, in some species, the flanks and the ventral side, however, are colored white.
In most cases, shortly after the end of the breeding season, according to the rearing of the young, it comes with the penguins moult , replacing the plumage. During this period, which can last depending on the type between two and six weeks, the birds consume their fat stores about twice as fast as before. For gentoo penguins ( Pygoscelis papua ) and Galápagos penguins (Spheniscus mendiculus ) is the time of moulting, however, is not fixed and can be done at any time between the breeding seasons. Non-breeding birds molt almost always earlier than their conspecifics breeding.
Penguins have to dye their plumage own dye group as Spheniscine are referred to [1] [2] - similar to some butterflies the pterins , both groups belong to the pteridines .
Sight and hearing
The eyes of the penguins are aligned sharp underwater vision; their cornea is extremely flat, so that the birds are slightly short-sighted on land. Especially with the deep-diving emperor penguins are pupils of the eye also extremely strain-and contractile, so that the eyes can in different light conditions that prevail at the surface and at 100 meters depth, adjust very quickly.From the pigment composition is concluded that penguins better in blue than in the red region of the spectrum can see and possibly even ultraviolet perceive light. Since red light is already filtered in the upper water layers, this can be an evolutionary adaptation suspect.
The ears have no externally perceivable structures, such as at most birds. They are watertight sealed by particularly strong springs while diving. For large penguins beyond the edge of the outer ear is enlarged so that it can be closed so that the middle and inner ear are protected against immersion-induced pressure damage.
Underwater give penguins - unlike on land where they communicate through a trumpet-like cries and loud buzz each other - no abnormal sounds. Whether they use their hearing vice versa for tracking prey or the perception of predators is unknown.
Dissemination
Penguins live in the open seas of the southern hemisphere. There they found especially in the coastal waters of Antarctica , in New Zealand , Southern Australia , South Africa , Namibia ( Penguin islands ), southern Angola , on the front of South America located Falkland Islands and on the west coast way up to Peru and on the äquatornah located Galápagos Islands . As cold-loving birds they occur in tropical areas only when cold water currents exist, which is about on the west coast of South America with the Humboldt current or to South Africa with the Benguela current on the Cape Peninsula is the case.
Most species live approximately between the 45th and the 60th Latitude South, while the largest number of individuals found around the Antarctic and on nearby islands. In the Northern Hemisphere, with the exception of live zoo animals and part of the population of the Galápagos penguin on the Galapagos island of Isabela no penguins.
Habitat
The actual habitat of the penguins is the open sea, to which they are adapted anatomically excellent. Only for breeding and spring changes they go ashore back, where they live on the rocky coasts of the southern continents in temperate forests of the temperate zone, subtropical sandy beaches, on largely barren lava fields, subantarktischem grassland or even on the ice of Antarctica. While the tropical species are site-faithful, others removed in the winter sometimes several hundred kilometers from the ocean to reach their breeding grounds.
Locomotion
The average achieved by penguins swimming speed of measurements suggest that around five to ten kilometers per hour, although higher speeds are possible in brief sprints. A particularly fast mode of locomotion is the "dolphin swim"; while leaving the animal like a dolphin suddenly each briefly the water. The reasons for this behavior are still in the dark: Maybe it uses the lower the air flow resistance, but perhaps it also serves to confuse predators.
When diving put some penguins amazing performances of the day: While the smaller species such as the Gentoo Penguin ( Pygoscelis papua ) usually dive only for about one, rarely more than two minutes, and then reach "only" depths of about 20 meters, are at Emperor penguins longer than 18 minutes lasting dives occupied, which already diving depths greater than 530 meters were measured. Although in particular the extreme benefits of large penguins today are not properly explained, it is known that the heart rate of the animals can be reduced up to one-fifth of the normal resting value while diving, which the oxygen consumption is reduced and thus made possible with the same amount of breathing air dive time multiplied. The pressure and temperature regulation in deep dives, however, is at the beginning of the 21st Century still a challenge for research.
When leaving the water penguins can overcome heights of up to 1.80 meters by leaps. Due to their relatively short legs they move on land mostly waddling away, a travel method, which, as result biomechanical studies, however, is surprisingly energy efficient. On the ice, however, they can also come rapidly forward by slither on his belly down the mountain. Some species lay between their breeding colonies and the sea returned miles of trails.
Nutrition
Depending on the size, penguins feed on fish , often, for example, of the Antarctic silverfish ( Pleuragramma antarcticum ), anchovies (Engraulidae) or sardines (in Clupeidae) of crustaceanssuch as krill or small squid swallowed that actively hunted by sight and still under water be. Parts, different types of the same habitat, they usually have different food preferences are consumed Adelie penguins and chinstrap penguins krill of different sizes.
The specialized on small crustaceans species are much more dependent on regular prey as the fish-hunting penguins, but will need to fish less energy: while the latter is often sufficient success in ten attempts, the former must per dive track up to 16 small crabs - the equivalent of a catch in six seconds - to meet their energy needs and their young. The number of dives per hunting trip is art and depending on the season: During the breeding season it is in chinstrap penguins ( Pygoscelis antarctica ) more than 190, while Emperor penguins can certainly do more than 860 dives in their long days of trains.
During the moult and in large penguins ( Aptenodytes ), Adelie penguins ( Pygoscelis adeliae ), chinstrap penguins ( Pygoscelis antarctica ) and Crested penguins ( Eudyptes ) in the breeding season must completely without food many penguins. Lent is different lengths of the various species and is about one month at the Adelie and Macaroni Penguins, can last more than three and a half months in male emperor penguins though. During this time, they can lose up to almost half of their body weight, and the birds will have to obtain their metabolic energy from the built-up before moulting or breeding season fat reserves. For gentoo penguins ( Pygoscelis papua ), yellow-eyed penguins ( Megadyptes antipodes ), little penguins ( Eudyptula minor ) or black-footed penguins ( Spheniscus demersus ) males and females, however, take turns brooding, so they must rely on their fat reserves only during moulting.
Your water needs to cover penguins mainly from the sea. Excess salt is excreted through special salt glands located above the eyes, again.
Reproduction
At what age penguins the first attempt to reproduce companies, depends on the one of a kind, from the other hand also of gender. Thus, dwarf, yellow-eyed, donkey and jackass penguins breed for the first time with two years, with females of Adelie, chinstrap, king and emperor penguins usually start a year later with the first breeding attempt, while the males of these species still further twelve months with reproductive wait. Macaroni penguins breed even before the age of five years.
The above information is statistical averages: In practice, it comes with age to longer and longer stays in the breeding colony until finally begins breeding behavior itself. So visit for example the king penguins just Annuals ever the colony, the animals appear in their second year of life there is often only for a few days. In the following years, the first appearance in the colony however, not only shifts from time to time forward, but also the residence time increases with age significantly. In males of the large penguins, it is not uncommon to start only from the age of eight with the brooding.
The seasonal onset of the breeding season is primarily dependent on climatic factors. While the north living Galápagos, minke and penguins can breed throughout the year back and raise little penguins in some cases even two broods per year, almost all start in sub-Antarctic living to arctic climates penguins generally in the spring or summer to lay eggs. A notable exception to this rule are the Emperor Penguins, where the breeding season begins in the fall. The boys are then calculated on during the Antarctic winter at temperatures of up to -40 degrees Celsius - unique adaptations to life in the cold are with them, therefore, essential for survival. The boy king penguins hibernate in the (further north) breeding colonies. They are from their parents but rarely fed at this time, so that there is a significant weight loss with them in the first winter.
Penguins are very social animals, not only in water but also on land. In particular, the egg-laying, hatching and further rearing found in many types synchronously in large breeding colonies instead, which may include up to five million animals in extreme cases.
For species not permanently settled the breeding season usually enter first the males the colony and try almost all kinds to secure a small territory, which includes but rarely more than one square meter of surface. Their social behavior is thus bound nest. The only exceptions are the United penguins not create nests for their eggs and only show towards their partners and their offspring behavioral problems.
Then the males try by exemplary trumpet call to attract a female. If it is not the first breeding attempt, this is often the partner from last year. The "divorce rate" is, in penguins, depending on different levels: The percentage of yellow-eyed penguins chose a different partner after a year, is very low at 14, her partner loyalty is also underlined by the fact that twelve percent of the partnerships last longer than seven years . Contrast, the annual separation rate is Adelie penguins at more than 50 percent, no partnerships are accordingly known that would have lasted more than six years. It is known that the breeding success of the previous year on the issue of partner selection plays an important role.
A close relationship exists between the complexity of social behavior and the mechanisms for partner recognition on the one hand and the colony size on the other hand: The mating rituals of in huge colonies close together living Adelie, chinstrap, gentoo and macaroni penguins are both visually and phonetically particularly striking; in dense vegetation living yellow-eyed penguins or the breed in widely spaced nests fairy penguins, however, are far more restrained.
Oviposition and brood reduction
After copulation, the male must be the balance on the back of a partner, is done laying eggs. During Emperor and King penguins hatch their respective single egg on their feet, put in all the other species, the penguin females at intervals of three to five days, two eggs in a simple nest, which is created from the existing around materials such as grasses or small pebbles . The egg color is white or greenish.
Not all eggs are hatched successfully: Especially among young couples, it often does not even hatch of the boys, so in two years parents slip rates of less than 33 percent were detected. The breeding success then rises rapidly with age, reaching values of more than 90 percent, only at very old penguin pairs then it drops because of decreasing fertility slowly to about 75 percent.
Usually the first egg is slightly larger than the second, so that the first chick after artabhängig between one and two months of incubation time something slips rather than its sibling chicks. As a result, the larger and older cub is preferred by his parents, for example, receives regularly more food than the second-hatched, which will soon neglected and usually dies quickly. This so-called brood reduction is an evolutionary adaptation to a limited food supply: Due to the rapid death of the second chick will ensure that the chances of survival of the first shall not be reduced by distributing the scarce resources on two offspring. Conversely, the parents have the second egg "reinsured" if the first chick should perish early.
While it comes in most species only scarce food supply during breeding reduction and Fiordland penguins ( E. pachyrhynchus ) even almost always raise both chicks, in all crested penguins brood reduction is the rule. Interestingly, in this genus, the second egg down the larger (the percentage difference between 20 and 70 percent), then slips the first pup from.
Rearing
The rearing of the young can be divided into two phases:
- In the first two to three - in large penguins even six - weeks and the chicks are permanently supervised by a parent, while the partner goes foraging.
- As soon as the young are grown up, starts the "kindergarten" time, in which the boys come together in groups, while both adult animals try to procure food. Depending on the type such also can Creches groups mentioned only a few animals include from neighboring nests such as in rein or eyeglasses penguins or be made up of thousands of individuals like Adelie, Gentoo penguins or large.
The feeding times are strongly artabhängig: Gentoo penguins feed their children every day, Adelie or chinstrap penguins only every two days, the United penguins often only once every four days or even less frequently. However, in the latter case the meals are so much the greater. The amount of feed is usually the level of development of the boys adapted, but still enormous in proportion to body weight: Even young chicks little penguin species can easily obtain 500 g of food per feeding; United penguins even give a blow up to one kilogram of fish on to her young.King Penguin Young may even be heavier than their parents after twelve months.
For species not permanent colony living for parental Mauser, the colony will leave quickly at the Macaroni Penguins, for example, within a week. The parental care is so complete in all likelihood - of a feeding at sea has not been reported, it is also difficult to imagine. The Gentoo penguins, who spend the entire year in the vicinity of their colony, the boys return for another two to three weeks regularly to their parents back and get there another feed, after which they too are on their own.
Life expectancy
Your chances of survival are low in the first twelve months. In Adelie penguins, for example, live after the tough first year being estimated at nearly half of all boys. An important factor which influences their life prospects significantly, the scope of the recognized in the breeding colony fat reserves, which in turn depends on the feeding by the adult animals and thus of their hunting success.
The survival probability of adult animals is, however, much higher: it is valid for the small Adelie penguins 70 to 80, at the United penguins even more than 90 percent. Penguins can reach an age of more than 25 years.
Natural enemies
Due to the mostly isolated from one breeding sites have adult penguins on land as well as no enemies; introduced by human mammals such as dogs and cats pose a serious threat, however, regional dar. penguins can use to defend both their beak and their fins as effective weapons. Chicks are unattended, however, quickly loot the Subantarktikskuas ( Catharacta antarctica ).These birds and some gulls take advantage of every opportunity to steal eggs.
Leopard seals ( Hydrurga leptonyx ), Southern fur seals ( Arctocephalus ), Australian ( Neophoca cinerea ) and New Zealand sea lions ( Phocarctos hookeri ) and Orcas ( Orcinus orca ) andsharks (Selachii) hunt penguins in the sea, especially given species of seals often patrol off in shallow water breeding colonies, where penguins their high maneuverability can not play well. It is estimated that about five percent of all Adelie penguins are killed every year in this way.
Therefore presumably occurs because the at first sight strange-looking fear of birds before going into the water to which they are so well adapted. Before Losschwimmen to penguins near often in smaller groups hesitant to the shore, obviously everyone with the desire to not be the first to have that enters the sea ( Penguin effect ); often takes this procedure up to half an hour. Once an individual has finally caught up enough courage and jump into the water, followed by all the others.
Endangering
Three species, the crown penguin ( Eudyptes sclateri ), the yellow-eyed penguin ( Megadyptes antipodes ) and the Galápagos Penguin ( Spheniscus mendiculus ) are at the beginning of the 21st Century classified as critically endangered, seven more are considered at risk.
For the reasons include the loss of habitat, such as the yellow-eyed penguin, whose stocks are threatened by increasing land use and human impacts on the dune system of New Zealand.Ausgewilderte mammals are also a danger, as in the Galápagos Penguin, which was limited to two islands breeding colonies have been decimated by stray dogs. In addition, climatic changes play a role: The populations of Galápagos penguins were decimated in the 1980s and 1990s due to the collapse of fish stocks, to the climate change brought in conjunction El Niño can be attributed phenomenon.
Rockhopper penguins ( Eudyptes chrysochome ), Magellanic penguins ( Spheniscus magellanicus ) or Humboldt penguins ( Spheniscus humboldti ) advised on their extensive forays by anchovies and sardines in sub-Antarctic waters again and again in conflict with the commercial fishing has, some of which specialize in the same types . During the part of the fishermen complaining about the loss of revenue is collected, many penguins lose their food source. However, there are efforts to defuse this competition conflict taking into account the interests of fishermen.
Penguins and Magellanic penguins, their colonies at the Cape of Good Hope in South Africa or at the Strait of Magellan located off South America, are particularly affected by the oil spill , which is due to the running there shipping and tanker routes in particular. Oily penguins can indeed captured, cleaned and released back into the wild, but this is a very time-consuming and costly process.
On the other hand, the intensive hunting has baleen whales (Mysticeti) and resulting krill propagation led to a significant increase in chinstrap and king penguins, most Antarctic species are due to the remoteness of their habitat as stable.
Penguins as objects of research - Danger by labeling and Fallacies
For some excitement among zoologists and climate researchers, the knowledge has ensured that just one for migration tests very common method of attaching marker bands on the fins (English flipper bands , fin straps) at significant risk, and in their way of life severely impaired free-living penguins. [3] [4] So shows a ten-year study of a colony of King penguins that tagged animals have a lower 16% chance of survival and 39% fewer chicks produce than non-labeled penguins. [5] is a declaration that the marking tapes by the ongoing friction can cause injury to the fins and the surrounding parts of the body, the kicking frequency of a medium-sized penguin during swimming is but about three beats per second. In addition to having fin straps marked penguins about 24% more power for swimming expend as unmarked animals. As a result of this impairment lasts with them foraging considerably longer, and they take on average 16 days later at the breeding grounds one than the other animals.
Penguins, as well as other predators at the top of the food chain , are often as integrative indicator species are used to study the influence of climate change on the marine ecosystem to investigate the southern polar ocean. The ten-year study shows clear, however, that marked animals in a different way to environmental changes - for example as a result of the warmer climate - react as untagged. This allows for considerable doubt on the validity of data obtained with the help of marker bands. Thus, the reliability of should the researchers fin strap-labeled penguins to be rethought as indicators of climate change and its implications for the south polar ecosystem. [4] [5]
Penguins and humans
The first encounter between humans and penguins is from Australia testified: Archaeological finds in bone deposits of Aborigines show that penguins in prehistoric times, formed a part of the food of Australian aborigines.
In Europe penguins were only towards the end of the 15th and with the beginning of the 16th Century by exploring voyages of Portuguese navigators under Vasco da Gama and Ferdinand Magellan known. The first known reference to the birds comes from the diary of Vasco da Gama of 25 November 1497, as this in Mossel Bay on the coast of South Africa was at anchor. He met there today as the Jackass Penguin ( Spheniscus demersus ) designated birds. The African Penguin is also the first scientifically described species, from which derives the Latin family name and order - he was already in 1758 by the Swedish taxonomist Carl Linnaeus in his work Systema Naturae treated. Almost all other species were, however, only the exploration of the Southern Ocean in the late 18th Century and 19 Discovered century.
Previously, whole colonies have been wiped out by gathering eggs for food and slaughter of adult animals for extracting oil from the rich fat layer. In addition, penguins were used as fuel for theTranerzeugung used. [6] [7]
Penguins are very curious birds and on land largely fearless. Unlike domesticated animals that have lost only by its frequent contact with people of their fear, most penguins inherently have no fear of humans. Whilst it naturally can not be scientifically confirmed, the presumption is of Antarctic travelers often been expressed that they had been held by the birds themselves for just a bit odd, built penguins.
In Central Europe penguins can only in zoos consider. Some offer to this end to so-called penguin marches in which the birds are let out of their enclosures mostly on weekends and can take a little tour around her home under the supervision and observation of the keepers. Penguin marches are including in the Zoological Gardens of Münster and Munich Hellabrunn offered in Switzerland in the Zurich Zoo , the penguin march in zoo of Edinburgh is regarded as worth seeing.
Penguins are considered very popular animals that can trigger passionate encouragement. Refrigerators are also named after them like ice hockey teams, and also a large English book publisher comes under its English name Penguin on. To date, this charm does not seem to be fading: as Linus Torvalds , the creator of the free software operating system Linux , was looking for a mascot, he decided withTux for a penguin (but with some influences of a duck).
Conversely, it was perhaps the peaceful and charming image that the author of the comic series Batman to moved to give the sinister figure of the supreme villain just the name Penguin. Danny DeVitoportrayed this role in 1992 in the movie Batman Returns . Friendly, peaceful encounter penguins to the viewer, however, in the children's cartoon character Pingu Swiss television.
The reason for the human sympathy caused by the apparent awkwardness of the animals unintentional comedy is often cited: the bouncing, daherschliddernden and waddling birds seem amusing to many viewers. This removes reminiscent of white shirt and black tuxedo, so very formal Menswear feathers reinforced this impression, and in some idioms the word "penguin" is even a jocular term for a Frack-bearing man.
The cause of the affection may be lower as well: So people do not last in the birds themselves - to which certainly contributes to the fact that penguins are one of the few animal species which are like humans upright on two legs.
Phylogeny
The phylogenetic relationships of penguins are controversial. As a comparatively safe is that they are descended from a group of seabirds, probably in the early to Cretaceous separated from the other groups of birds, and today the loons (Gaviiformes), Procellariiformes (Procellariiformes), Pelecaniformes (Pelecaniformes) and perhaps the grebes ( Podicipediformes) are counted.
Morphological analyzes have penguins as sister group of a taxon from from sea and grebes:
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Molecular genetic results, however, see loons and Procellariiformes as the closest relatives; if the latter do not form a natural group, which are perhaps even albatrosses the penguins neighbors are birds:
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The since the early Tertiary known fossils provide little insight into the phylogenetic relationships, as even the early penguins very clearly from all other birds. However, the wing bone (pterygoid) is reminiscent of the extinct genusParaptenodytes to the corresponding bones of the Procellariiformes, and the long pointed beak of the genus Palaeeudyptes has similarities with the beaks of the loons on. The latter can be like the penguins dive underwater, but get their propulsion by the feet and not by fins. However, there is fossil evidence that the ancestors of the loons continues moving under water like modern penguins with the help of their wings.
As the appearance of the penguins was, is unknown: The first penguin fossils from the Eocene have survived 55 million years ago and on the front Antarctica nearby Seymour Island were found to already show the typical features of penguin.
It is clear that the penguins are descended from flying birds that were probably already chasing like today's loons under water. But the flight in air and underwater swimming place very different demands on the wings of a bird - as a result, the flying and diving ancestors of penguins little larger than about its been today's dwarf or penguins. This results in a - hypothetical - scenario in which the penguins are descended from a population of small sedentary marine birds that lived in water temperatures above about 15 degrees Celsius in coastal waters of the subtropics and temperate zone such as the Galápagos Penguins on isolated islands nests. As part of an ever better adaptation to the sea, their wings were ever to fins, while the legs hiked back to reduce drag while swimming. Although By specializing in the marine habitat and increasing body size was also a loss of the ability to fly accompanied and enforced by the recessed legs waddling ashore endangered animals in theory and on land, which was, however, in the absence of predators not an evolutionary disadvantage.
The exact area where the event was the development of the Penguins, today can not be reconstructed, but hypothetically both New Zealand and the then still considerably warmer Antarctica considered. Undeniably's just that the Penguins have emerged in the southern hemisphere, as no single fossil was found north of the equator. Warm equatorial ocean currents presented in the following period then apparently an insurmountable barrier for the birds represent, next to the high number faster predatory fish is in tropical latitudes such as sharks considered as the cause of this in mind that the Penguins have never crossed the equator.
Further phylogenetic development can only be traced roughly, even if up to the beginning of the 21st Century 17 fossil species have been described at least. No complete skeleton has been preserved, most fossils also come from large birds, this is probably just a selection effect , which can be explained by the much better fossilization of their bones, and probably does not have any systematic significance.
The highest species diversity of penguins was in the Tertiary , particularly in the geological ages of the Oligocene and early Miocene achieved. At this time also lived the largest penguins, which reached a body length of up to 1.70 meters. One of these types was, for example Pachydyptes ponderosus . Why the giant penguins finally became extinct in the Miocene, is unknown; speculatively increasing competition from is seals (Pinnipedia) and whales (Cetacea) stated: The giant penguins needed to support the body weight at their regular ashore very large legs and feet that dragged uselessly in the sea had to be - unlike the fully marine mammals that could reshape their hind limbs to fins or equal abandon completely.
A little earlier, in about 25 million years ago, at the turning point of the Oligocene and Miocene, also began triggered by the opening of the Drake Passage between Antarctica and South America form the cold circumpolar current , the Antarctic climate insulated and thus lowering the water temperature by more than ten degrees brought about. As already living water and therefore well insulated animals, the penguins were relatively well prepared for this sudden drop in temperature, so that one of exaptation can speak, in this case, the utilization of a developed for a particular ecological niche feature combination for a different niche.
The modern penguin species appear only in the Pliocene to three million years ago.
System
- The Pygoscelis ( Pygoscelis ) are, without exception, feathery black and white and molt at the end of each breeding season. There are three types, the gentoo penguin ( P. papua ), the Adelie ( P. adeliae ) and chinstrap ( P. antarctica ), which is also called Chinstrap penguin. All species are very social, the Chinstrap Penguin is on Deception Iceland with an estimated five million breeding pairs of the largest penguin colony.
- The United penguins ( Aptenodytes ), to which one the King Penguin ( A. patagonicus ) and Emperor Penguin ( A. forsteri is one), include the two largest species of penguin. They have a long, slender, slightly curved beak and in each case a characteristic orange patch on the neck. United penguins build a nest, the only egg is hatched instead on the feet.
- The macaroni penguins ( Eudyptes ) comprise the greatest biodiversity. The group is quite diverse, but characterized by yellow-orange feathers on the head. Macaroni penguins live mainly in the waters around New Zealand, their colonies exist only during the breeding season. For all species it comes to obligate brood reduction: Although always two eggs are laid, only one young is raised in order to avoid an unfavorable food division, in the end, none of the pups gets enough food.
- The genus of yellow-eyed penguins ( Megadyptes ) is monotypic, ie has only one type, the yellow-eyed penguin ( M. antipodes ), which breeds in southern New Zealand. Yellow feathers indicate its close relationship with the Macaroni Penguins.
- Also the genre of fairy penguins ( Eudyptula ) contains only one type, the Little Penguin ( E. minor ), some taxonomists reviewing otherwise be summarized as subspecies Weißflügel Penguin ( E. minor albosignata ) but as another, independent Art Little Penguins are the smallest penguins and live in the waters of Australia and New Zealand.
- The Penguins ( Spheniscus ) form a very homogeneous species, which is probably very recent origin. The four types are distinguished by black stripes on the flanks, a characteristic black-and-white head pattern and bare skin on the head. Penguins are the most northerly living penguins and are at home in tropical regions. The birds remain throughout the year in their colonies; breeding season and moult are usually highly variable and quite regardless of the season. Fairy penguins and the boys of jackass penguins look very similar, a finding which could be taken as an indication of the close relationship of the two genera.
The phylogenetic relationships of the genera come together in the following diagram for expression, which is based on a synthesis of molecular genetic and morphological data:
| Penguins (Spheniscidae) |
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While the sister group relationship of crested penguins and yellow-eyed penguin and of little penguin and black-footed penguins is considered somewhat controversial, the classification of the other two genera with greater uncertainty is associated.
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