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Modern Penguin (Family: Spheniscidae, Subfamily: Spheniscinae) - Wiki
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Penguin
From Wikipedia, the free encyclopedia
Order: Sphenisciformes
Family: Spheniscidae
Subfamily Spheniscinae
[Photo] Isabelline Ad??lie penguin on Gourdin Island, December 2002. I took this photo on Gourdin Island in December 2002. Details on the trip can be found at http://www.geocities.com/peyre1347/index.htm Author: http://en.wikipedia.org/wiki/User:Peyre License: public domain.
Penguins (order Sphenisciformes, family Spheniscidae) are a group of aquatic, flightless birds living almost exclusively in the Southern Hemisphere.
The number of penguin species is debated. Depending on which authority is followed, penguin biodiversity varies between 17 and 20 living species, all in the subfamily Spheniscinae. Some sources consider the White-flippered Penguin a separate Eudyptula species, while others treat it as a subspecies of the Little Penguin (e.g. Williams, 1995; Davis & Renner, 2003); the actual situation seems to be more complicated (Banks et al. 2002). Similarly, it is still unclear whether the Royal Penguin is merely a color morph of the Macaroni penguin. Also eligible to be a separate species is the Northern population of Rockhopper penguins (Davis & Renner, 2003). Although all penguin species are native to the southern hemisphere, they are not, contrary to popular belief, found only in cold climates, such as Antarctica. In fact, only a few species of penguin actually live so far south. At least ten species live in the temperate zone; one lives as far north as the Gal??pagos Islands: the Gal??pagos Penguin.
The largest living species is the Emperor Penguin (Aptenodytes forsteri): adults average about 1.1 m (3 ft 7 in) tall and weigh 35 kg (75 lb) or more. The smallest penguin species is the Little Blue Penguin (also known as the Fairy Penguin), which stands around 40 cm tall (16 in) and weighs 1 kg (2.2 lb). Among extant penguins larger penguins inhabit colder regions, while smaller penguins are generally found in temperate or even tropical climates (see also Bergmann's Rule). Some prehistoric species attained enormous sizes, becoming as tall or as heavy as an adult human (see below for more). These were not restricted to Antarctic regions; on the contrary, subantarctic regions harboured high diversity, and at least one giant penguin occurred in a region not quite 2000 km south of the Equator 35 mya, in a climate decidedy warmer than today.
Most penguins feed on krill, fish, squid, and other forms of sealife caught while swimming underwater. They spend half of their life on land and half in the oceans.
Penguins seem to have no special fear of humans and have approached groups of explorers without hesitation. This is probably on account of there being no land predators in Antarctica or the nearby offshore islands that prey on or attack penguins. Instead, penguins are at risk at sea from predators such as the leopard seal. Typically, penguins do not approach closer than about 3 meters (9 ft); they become nervous at about that distance. This is also the distance that Antarctic tourists are told to keep from penguins (tourists are not supposed to approach closer than 3 meters, but are not expected to withdraw if the penguins come closer).
Systematics
ORDER SPHENISCIFORMES
Family Spheniscidae
Subfamily Spheniscinae - Modern penguins
* Genus Aptenodytes - Great penguins (2 species)
King Penguin, Aptenodytes patagonicus
Emperor Penguin, Aptenodytes forsteri
* Genus Pygoscelis - Brush-tailed penguins (3 species)
Adelie Penguin, Pygoscelis adeliae
Chinstrap Penguin, Pygoscelis antarctica
Gentoo Penguin, Pygoscelis papua
* Genus Eudyptula - Little penguins (2 species)
Little Blue Penguin (or Fairy Penguin), Eudyptula minor
Northern Little Penguin, Eudyptula albosignata (provisional)
- White-flippered Penguin, Eudyptula albosignata albosignata
* Genus Spheniscus - Banded penguins (4 species)
Magellanic Penguin, Spheniscus magellanicus
Humboldt Penguin, Spheniscus humboldti
Gal??pagos Penguin, Spheniscus mendiculus
African Penguin or Jackass Penguin, Spheniscus demersus
* Genus Megadyptes - Yellow-eyed Penguin
Yellow-eyed Penguin or Hoiho, Megadyptes antipodes
* Genus Eudyptes - Crested penguins (6-8 living species)
Fiordland Penguin, Eudyptes pachyrhynchus
Snares Penguin, Eudyptes robustus
Erect-crested Penguin, Eudyptes sclateri
(Southern) Rockhopper Penguin, Eudyptes chrysocome
- Southern Rockhopper Penguin (Indian & Pacific Ocean), Eudyptes chrysocome filholi
- Southern Rockhopper Penguin (Atlantic Ocean), Eudyptes chrysocome chrysocome
- Northern Rockhopper Penguin or Mosely's Penguin, Eudyptes chrysocome moselyi
Royal Penguin, Eudyptes schlegeli - possibly just a morph of Eudyptes chrysolophus
Macaroni Penguin, Eudyptes chrysolophus
http://en.wikipedia.org/wiki/Spheniscinae
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Sphenisciformes comprises one family (Spheniscidae), six genera, and 17 species.
Penguins are restricted to the Southern Hemisphere where they are oceanic or coastal denizens.
Penguins of the Antarctic and Sub Antarctic are oceanic and breed on coasts and pack ice. Species nearer the equator may be oceanic or inhabit inshore waters and breed in coastal or forest habitats.
Penguins are notable for their upright posture and stiff wings that cannot be folded against the body. Penguins are medium to large birds (1-40 kg; 40-115 cm) with a thick layer of fat beneath the skin. Adult plumage is blue-black or gray dorsally and white ventrally, sometimes with distinctive coloring or plumes on the head. Chicks are either entirely brown-gray, or white ventrally. Juveniles have adult-like plumage. Sexes are similar. Feathers are small and continuous (no feather tracts). Bills are long and often laterally compressed, holorhinal (nostril entire), impervious nares, and schizognathous palate. Penguins are flightless divers with poorly pneumatized skeleton, carinate sternum with two lateral notches, 15 cervical vertebrae and basipterygoid processes absent. Wings are modified as flippers (wing skeleton flattened and partially fused), base of wing has vascular rete (blood vessel configuration in which cooler blood returning to the body absorbs heat from blood flowing out to the wing), pectoral muscles are large, but biceps bracii absent (unique to penguins). Legs are short; placed far posterior on body; flat tarsometatarsus is incompletely fused; palmate feet with four forward pointing toes. Bilobed oil gland is tufted.
Galapagos Penguins (Spheniscus mendiculus) have been observed foraging with boobies, terns, and shearwaters.
Penguins dive well and use their flippers to swim underwater in pursuit of prey items. Prey items include anchovies, pilchards, cuttlefish, squid, and krill.
Predators of penguins include: humans, Leopard seals (Hydrurga leptonyx), Killer whales, sharks, stoats, rats (Rattus norvegicus), Weka (Gallirallus australis).
Hatching may be synchronous or asynchronous (one or two days apart). Often the younger of two chicks will not survive. Chicks are altricial and take 10-52 weeks to fledge. In some species chicks remain with and are regularly fed by adults until fledged. In other species the chicks may be fed till nearly adult size, then fast for several months while huddling with other chicks for warmth in a nursery. Average age of first reproduction differs between species, ranging from two to five years old. Life expectancy from fledging may be 20 years. Chicks have two nestling downs.
Penguins are considered monogamous and individuals often nest at the same nest site, with the same partner from the previous year. In some species, 13 year pairings have been observed. Courtship displays are varied and complex, and may include loud raucous vocalizations, 'mutual ecstatic displays'(mate recognition behaviors), and beak slapping (or bill-fencing displays).
Most penguins breed in large colonies, one of the largest being the Macaroni penguin colony in South Georgia, which is estimated to be five million pairs. Antarctic, sub-Arctic and cold temperate penguins breed in either spring or summer, whereas species in warmer climes have more continuous breeding seasons. Penguin nests range from shallow dishes of pebbles and vegetation, to holes dug in soft soil, to rocky depressions, to the space between the top of the feet and the pouch-like fold of abdominal skin. Nesting areas are diverse and include small caves, burrows, coastal forests, and pack ice. Females lay one to two whitish eggs per clutch, with two to four days between egg laying.
Overall, penguin males and females share the parental care duties, but incubation, brooding, and feeding-fasting cycles are diverse and complex. Some species begin fasting at the onset of the breeding season. In some species males and females share incubation, whereas in others incubation is primarily uniparental. Incubation duration ranges from 30-64 days, whereas parental incubation shifts may range from 5-64 days. Usually the male takes the first incubation shift after the female has laid the clutch. One of the longest incubation and fasting shifts occurs in the Emperor penguin. During the Antarctic winter, the female Emperor penguin lays one egg then departs to feed at sea. The male fasts while incubating for 60 days till the female returns at hatching time. At that point the female begins brood care while the male goes to feed at sea. Contrastingly, during the Antarctic summer the female Chinstrap penguin lays two eggs. The female then fasts while incubating for 30 days until the male returns from feeding at sea.
Some penguins waddle along shorelines and ice, whereas others hop from rock to rock. When on ice or snow, penguins can move swiftly by tobogganing (sliding along propelled by wings and feet). Penguins also use their modified wings as flippers to swim underwater. The Emperor penguin is an exceptional diver and can stay submerged for 18 minutes and dive as deep as 500 meters. Swimming speeds average two to three knots, but may reach 15-20 knots for short distances. Swimming often includes porpoising (repeatedly breaking the water's surface with enough momentum to lift the bird into the air for about one meter.)
Penguins are highly social, oftentimes breeding in large colonies. Some species forage cooperatively and may dive synchronously while foraging in small or large groups. Species that breed in large colonies often have elaborate visual and vocal displays.
Vocalizations are characterized as loud, short braying. In colonial species in which chicks group together in a nursery (or cr??che) recognition of mates and offspring seems based on individually distinguishable calls.
Historically penguins were hunted and boiled to extract oil from the heavy layer of fat beneath the skin. At the turn of the century, approximately 150,000 Royal penguins (Edypes schlegeli) were harvested each year for 20 years from Macquarie Island (located south of New Zealand). On islands off of the coasts of Peru and Chile, penguin eggs and guano (dry bird droppings) are collected for local use.
Twelve penguin species are included in the IUCN Red List of Threatened Species, three of those (Eudyptes sclateri, Megadytpes antipodes, Spheniscus mendiculus) are listed as Endangered. Major threats to wild populations include: hybridization, destruction of breeding habitat, human disturbance, egg and guano collection, predation by introduced mammals, commercial fishing, and oil spills.
Despite evidence derived from osteology, anatomy, behavior, histology, and protein comparisons, the evolutionary relationships of penguins remain elusive. Penguins have been considered related to loons (gaviids), grebes (podicepids), pelicans (pelicanids), and/ or tube-noses (procellariids). DNA hybridization places penguins within Cinconiiformes and estimates a close relationship between sphenicids, gaviids, frigatids, and tubenoses (procellariids).
At least eighteen penguin species are represented in the fossil record of the Southern Hemisphere and date back to the middle or late Eocene. A common ancestry for penguins and procellariids is suggested by the presence of tubular nostrils in fossil penguins and in the extant Little Penguin (Eudyptula minor). |
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