Information
and generalised research about the penguin animal group, general
information and facts about the flightless birds- sources linked above.
pen·guin
noun /ˈpeNGgwin/ /ˈpengwin/
penguins, plural
A
large flightless seabird of the southern hemisphere, with black upper
parts and white underparts and wings developed into flippers for
swimming under water.penguins, plural
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 become 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): 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 (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.
Etymology
The etymology of the word "penguin" is highly disputed. The English word is not apparently of French, nor of Breton or Spanish origin (both attributed to the French word pingouin "auk"), but first appears in English or Dutch.
Some dictionaries suggest a derivation from Welsh pen "head" and gwyn "white", including 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, which had white spots in front of its eyes (although its head was black).
An alternative etymology, found in a few English dictionaries, links the word to Latin pinguis
"fat", from its perceived appearance. This etymology would be
improbable if "penguin" were found to have been originally applied to
the great auk, as some sources suggest.
A third theory states that the word is an alteration of “pen-wing”,
with reference to the rudimentary wings of great auks. This has been
criticised for the unexplained nature of the alteration of the word.
Systematics and evolution
Living species and recent extinctions
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; the actual situation seems to be more complicated. 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).
Subfamily Spheniscinae – Modern penguins
- Aptenodytes – Great penguins
- King Penguin, Aptenodytes patagonicus
- Emperor Penguin, Aptenodytes forsteri
- Pygoscelis – Brush-tailed penguins
- Adélie Penguin, Pygoscelis adeliae
- Chinstrap Penguin, Pygoscelis antarctica
- Gentoo Penguin, Pygoscelis papua
- Eudyptula – Little penguins
- Little Blue Penguin, Eudyptula minor
- White-flippered Penguin, Eudyptula albosignata (provisional)
- Spheniscus – Banded penguins
- Magellanic Penguin, Spheniscus magellanicus
- Humboldt Penguin, Spheniscus humboldti
- Galapagos Penguin, Spheniscus mendiculus
- African Penguin, Spheniscus demersus
- Megadyptes
- Yellow-eyed Penguin, Megadyptes antipodes
- Waitaha Penguin, Megadyptes waitaha (extinct)
- Eudyptes – Crested penguins
- Fiordland Penguin, Eudyptes pachyrynchus
- Snares Penguin, Eudyptes robustus
- Erect-crested Penguin, Eudyptes sclateri
- Western Rockhopper Penguin, Eudyptes chrysocome
- Eastern Rockhopper Penguin, Eudyptes filholi
- Northern Rockhopper Penguin, Eudyptes moseleyi
- Royal Penguin, Eudyptes schlegeli (disputed)
- Macaroni Penguin, Eudyptes chrysolophus
- Chatham Penguin, Eudyptes sp. (extinct)
Evolution
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, the evolution of the living genera can be considered resolved by now.
The basal penguins lived around the time of the Cretaceous–Tertiary extinction event somewhere 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 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. 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 (see also Flightless Cormorant).
Anatomy and physiology
Penguins are superbly adapted to aquatic life. Their vestigial wings
have become flippers, useless for flight in the air. In the water,
however, penguins are astonishingly agile. Penguins' swimming looks very
similar to bird's flight in the air. Within the smooth plumage
a layer of air is preserved, ensuring buoyancy. The air layer also
helps insulate the birds in cold waters. On land, penguins use their tails and wings to maintain balance for their upright stance.
All penguins are countershaded for camouflage – that is, they have black backs and wings with white fronts. A predator looking up from below (such as an orca or a leopard seal)
has difficulty distinguishing between a white penguin belly and the
reflective water surface. The dark plumage on their backs camouflages
them from above.
Diving penguins reach 6 to 12 km/h (3.7 to 7.5 mph), though there are
reports of velocities of 27 km/h (17 mph) (which are more realistic in
the case of startled flight).
The small penguins do not usually dive deep; they catch their prey near
the surface in dives that normally last only one or two minutes. Larger
penguins can dive deep in case of need. Dives of the large Emperor
Penguin have been recorded reaching a depth of 565 m (1,870 ft) for up
to 22 minutes.
Penguins either waddle on their feet or slide on their bellies across
the snow, a movement called "tobogganing", which conserves energy while
moving quickly. They also jump with both feet together if they want to
move more quickly or cross steep or rocky terrain.
Penguins have an average sense of hearing for birds; this is used by parents and chicks to locate one another in crowded colonies.
Their eyes are adapted for underwater vision, and are their primary
means of locating prey and avoiding predators; in air it has been
suggested that they are nearsighted, although research has not supported this hypothesis.
Penguins have a thick layer of insulating feathers that keeps them
warm in water (heat loss in water is much greater than in air). The
Emperor Penguin (the largest penguin) has the largest body mass of all
penguins, which further reduces relative surface area and heat loss.
They also are able to control blood flow to their extremities, reducing
the amount of blood that gets cold, but still keeping the extremities
from freezing. In the extreme cold of the Antarctic winter, the females
are at sea fishing for food leaving the males to brave the weather by
themselves. They often huddle together to keep warm and rotate positions
to make sure that each penguin gets a turn in the center of the heat
pack.
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 Auk of the Northern Hemisphere is superficially similar to penguins. They are not related to the penguins at all, but considered by some to be a product of moderate convergent evolution.
Isabelline penguins
Perhaps one in 50,000 penguins (of most species) are born with brown rather than black plumage. These are called isabelline penguins, possibly in reference to the legend that the archduchess Isabella of Austria vowed not to change her undergarments until her husband's siege of Ostend was successful—which took over three years to accomplish.
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.
Distribution and habitat
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 actually live so far south. At least 10 species live in the temperate zone; one, the Galápagos Penguin, lives as far north as the Galápagos Islands, but this is only made possible by the cold, rich waters of the Antarctic Humboldt Current that flows around these islands.
Several authors have suggested that penguins are a good example of Bergmann's Rule
where larger bodied populations live at higher latitudes than smaller
bodied populations. There is some disagreement about this, and several
other authors have noted that there are fossil penguin species that
contradict this hypothesis and that ocean currents and upwellings are
likely to have had a greater effect on species diversity than latitude
alone.
Major populations of penguins are found in: Antarctica, Argentina, Australia, Chile, New Zealand, and South Africa.
Behaviour
Breeding
Penguins for the most part breed in large colonies, the exceptions
being the Yellow-eyed and Fiordland species; these colonies may range in
size from as few as a 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 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; 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 the weight of a
penguin egg, presumably to minimise 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 it if parents are delayed in returning with food.
When mothers lose a chick, they sometimes attempt to "steal" another
mother's chick, usually unsuccessfully as other females in the vicinity
assist the defending mother in keeping her chick. In some species, such as Emperor Penguins, young penguins assemble in large groups called crèches.
Penguins and humans
Penguins seem to have no special fear of humans, and have approached
groups of explorers without hesitation. This is probably because
penguins have no land predators in Antarctica or the nearby offshore islands. Instead, penguins are at risk at sea from predators such as the leopard seal.
Typically, penguins do not approach closer than about 3 meters (10 ft)
at which point they become nervous. 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).
In popular culture
Penguins are popular around the world, primarily for their unusually
upright, waddling gait and (compared to other birds) lack of fear of
humans. Their striking black-and-white plumage is often likened to a tuxedo suit. Mistakenly, some artists and writers have penguins based at the North Pole. This is incorrect, as there are almost no wild penguins in the northern hemisphere, except the small group on the northernmost of the Galápagos. The cartoon series Chilly Willy
helped perpetuate this myth, as the title penguin would interact with
northern-hemisphere species such as polar bears and walruses.
Penguins have been the subject of many books and films such as Happy Feet, Surf's Up and The Penguins of Madagascar, all CGI films; March of the Penguins, a documentary based on the migration process of the Emperor Penguin; and a parody titled Farce of the Penguins. Mr. Popper's Penguins is a children's book written by Richard & Florence Atwater; it was named a Newbery Honor Book
in 1939. Penguins have also found their way into a number of cartoons
and television dramas; perhaps the most notable of these is Pingu, created by Silvio Mazzola in 1986 and covering more than 100 short episodes. Entertainment Weekly
put it on its end-of-the-decade, "best-of" list, saying, "Whether they
were walking (March of the Penguins), dancing (Happy Feet), or hanging
ten (Surf's Up), these oddly adorable birds took flight at the box
office all decade long."
The tendency of penguins to form large groups feeds the stereotype
that they all look exactly alike, a popular notion exploited by
cartoonists such as Gary Larson.
Penguins featured regularly in the cartoons of UK cartoonist Steve Bell in his strip in The Guardian Newspaper, particularly during and following the Falklands War.
In the mid-2000s, penguins became one of the most publicized species of animals that form lasting homosexual couples. A children's book, And Tango Makes Three, was written about one such penguin family in the New York Zoo.
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