Wednesday, 20 February 2013

Cute Pictures Of Baby Penguins

Source(google.com.pk)
Cute Pictures Of Baby Penguins Biography
Penguins (order Sphenisciformes, family Spheniscidae) are a group of aquatic, flightless birds living almost exclusively in the southern hemisphere, especially in Antarctica. Highly adapted for life in the water, penguins have countershaded dark and white plumage, and their wings have evolved into flippers. Most penguins feed on krill, fish, squid and other forms of sealife caught while swimming underwater. They spend about half of their lives on land and half in the oceans.
Although all penguin species are native to the southern hemisphere, they are not found only in cold climates, such as Antarctica. In fact, only a few species of penguin live so far south. Several species are found in the temperate zone, and one species, the Galápagos Penguin, lives near the equator.
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 (75 lb) or more. The smallest penguin species is the Little Blue Penguin (Eudyptula minor), 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. 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 2,000 km south of the equator 35 mya, in a climate decidedly warmer than today.The word "Penguin" first appears in the 16th century as a synonym for Great Auk.[1] It may be derived from the Welsh pen gwyn "white head", although the etymology is debated. When European explorers discovered what are today known as penguins in the Southern Hemisphere, they noticed their similar appearance to the Great Auk of the northern hemisphere, and named them after this bird, although they are not related.[2]
The etymology of the word "penguin" is still debated. The English word is not apparently of French,[1] nor of Breton[3] or Spanish[4] origin (both attributed to the French word pingouin "auk"), but first appears in English or Dutch.[1]
Some dictionaries suggest a derivation from Welsh pen, "head" and gwyn, "white", including the Oxford English Dictionary,[5] the American Heritage Dictionary,[6] the Century Dictionary[7] and Merriam-Webster,[8] 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).
An alternative etymology links the word to Latin pinguis which means "fat". In Dutch the alternative word for penguin is 'fat-goose' ('vetgans' see: Dutch wiki or dictionaries under Pinguïn), and would indicate this bird received its name from its appearance.
Systematics and evolution
Living species and recent extinctions
Adélie Penguin (Pygoscelis adeliae) feeding young. Like its relatives, a neatly bi-coloured species with a head marking.
Magellanic Penguins (Spheniscus magellanicus). The closed neck collar denotes this species.
Closeup of Southern Rockhopper Penguin (Eudyptes chrysocome)
Two King Penguins and one Gentoo Penguin walking on a beach on South Georgia, British overseas territory
The number of extant 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;[9][10] the actual situation seems to be more complicated.[11] Similarly, it is still unclear whether the Royal Penguin is merely a color morph of the Macaroni penguin. The status of the Rockhopper penguins is also unclear.
Updated after Marples (1962), Acosta Hospitaleche (2004), and Ksepka et al. (2006).The evolutionary history of penguins is well-researched and represents a showcase of evolutionary biogeography; though as penguin bones of any one species vary much in size and few good specimens are known, the alpha taxonomy of many prehistoric forms still leaves much to be desired. Some seminal articles about penguin prehistory have been published since 2005,[18][19][20][21] the evolution of the living genera can be considered resolved by now.
The basal penguins lived around the time of the Cretaceous–Paleogene extinction event somewhere in the general area of (southern) New Zealand and Byrd Land, Antarctica.[20] Due to plate tectonics, these areas were at that time less than 1,500 kilometres (930 mi) apart rather than the 4,000 kilometres (2,500 mi) of today. The most recent common ancestor of penguins and their sister clade can be roughly dated to the Campanian–Maastrichtian boundary, around 70–68 mya.[19][21][22] What can be said as certainly as possible in the absence of direct (i.e., fossil) evidence is that by the end of the Cretaceous, the penguin lineage must have been evolutionarily well distinct, though much less so morphologically; it is fairly likely that they were not yet entirely flightless at that time, as flightless birds have generally low resilience to the breakdown of trophic webs that follows the initial phase of mass extinctions because of their below-average dispersal capabilities.
Cute Pictures Of Baby Penguins Biography
Cute Pictures Of Baby Penguins Biography
Cute Pictures Of Baby Penguins Biography
Cute Pictures Of Baby Penguins Biography
Cute Pictures Of Baby Penguins Biography
Cute Pictures Of Baby Penguins Biography
Cute Pictures Of Baby Penguins Biography
Cute Pictures Of Baby Penguins Biography
Cute Pictures Of Baby Penguins Biography
Cute Pictures Of Baby Penguins Biography
Cute Pictures Of Baby Penguins Biography

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