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Penguin

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For other uses, see Penguin (disambiguation).

Penguins
Chinstrap Penguin, Pygoscelis antarctica
Scientific classification
Kingdom:
Animalia
Phylum:
Chordata
Class:
Aves
Order:
Sphenisciformes

Sharpe, 1891
Family:
Spheniscidae

Bonaparte, 1831
Modern Genera

Penguins (order Sphenisciformes, family Spheniscidae) are an order of aquatic, flightless birds living in the southern hemisphere.

Species and habitats

The number of extant species has been and still is a matter of debate. The numbers of penguin species listed in the literature vary between 16 and 19 species. Some sources consider the White-Flippered Penguin a seperate Eudyptula species, although today it is generally considered a subspecies of the Little penguin (e.g. Williams, 1995; Davis & Renner, 2003). Similarily, it is still unclear whether the Royal Penguin is merely a colour morph of the Macaroni penguin. Also possibly eligible to be treated as a seperate 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. Three species live in the tropics; one lives as far north as the Galápagos Islands (the Galápagos Penguin) and will occasionally cross the equator while feeding.

The largest species is the Emperor Penguin (Aptenodytes forsteri): adults average about 1.1 meters (3 ft 7 in) tall and weigh 35 kilograms (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 kilogram (2.2 lb). Generally larger penguins retain heat better, and thus inhabit colder regions, while smaller penguins are found in temperate or even tropical climates. The rarest type of penguin is the yellow-eyed penguin (Megadyptes antipodes) and is probably the most ancient of all living penguins: adults average about 65 cm tall and weigh 5-6 kilograms. It is estimated that there are only 1500 breeding pairs left in the world.

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.

One of the most baffling forms of behavior of the penguin comes when a mother loses her chick, either due to its being unable to endure its first storm, or due to other reasons such as predators. When a mother loses its chick, they have been known to actually attempt to steal another mother's living chick- presumably in order to deal with the grief of the loss. This behavior has amazed scientists, as it is an emotional outburst opposed to an instinctual behavior; something many wild animals do not exhibit when losing their young. Many have used this as prime evidence for decades that many animals have near human-like emotions and feelings, often for the sake of animal rights. Naturally, the other females in the penguin groups dislike this behavior and will help the defending mother keep her chick. This behaviour, however, might be better explained as a means for the female, or the male, to retain the full cooperation of the other parent in rearing the young, given that the bonding is monogamous; most likely there are differences between males and females in regards to the likelihood of chick-robbing and between species in relation to whether the monogamy is seasonal or permanent. Penguins seem to have no fear of humans, and have approached groups of explorers without hesitation.

Evolution

The evolutionary history of penguins is poorly understood, as penguin fossils are rare. The oldest known fossil penguin species are the Waimanu, which lived in the early Paleocene epoch of New Zealand, about 62 million years ago. While they were not as well adapted to aquatic life as modern penguins (which first emerged in the Eocene epoch 40 million years ago), Waimanu were flightless and loon-like, with short wings adapted for deep diving. These fossils prove that prehistoric penguins were already flightless and seagoing, so their origins probably reach as far back as 65 million years ago, before the extinction of the dinosaurs. Penguin ancestry beyond Waimanu is not well known, though some scientists (Mayr, 2005) think the penguin-like plotopterids (usually considered relatives of anhingas and cormorants) may actually be an early sister group of the penguins, and that penguins may have ultimately shared a common ancestor with the Pelecaniformes.

Palaeeudyptines

Traditionally, most extinct species of penguins have been placed in the possibly paraphyletic sub-family called Palaeeudyptinae. For a complete list of these genera, see the Classification section below.

Anatomy

Penguins are superbly adapted to an aquatic life. Their wings have become flippers, useless for flight in the air. In the water, however, penguins are astonishingly agile. Within the smooth plumage a layer of air is preserved, ensuring buoyancy. The air layer also helps insulate the birds in cold waters. The plumage of penguins in tropical and temperate zones is much thinner than that of more southern species.

On land, penguins use their tails and wings to maintain balance for their upright stance.

All penguins have a white underside and a dark (mostly black) upperside. This is for camouflage. 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, though there are reports of velocities of 27 km/h (which are probably 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 which reach a depth of 565 m (1870 ft) and last up to 20 minutes.

Penguins either waddle on their feet or slide on their bellies across the snow, a movement called "tobogganing", which allows them to conserve energy and move relatively fast at the same time.

Penguins have an excellent sense of hearing. Their eyes are adapted for underwater vision, and are their primary means of locating prey and avoiding predators; in air, conversely, they are nearsighted. Their sense of smell has not been researched so far.

They are able to drink salt water safely because their supraorbital gland filters excess salt from the bloodstream. [1] [2] [3] The salt is excreted in a concentrated fluid from the nasal passages.

Penguins have no external genitalia.[4] Consequently, chromosome testing must be done in order to determine a penguin's sex.

Mating habits

Some penguins mate for life, while others for just one season. They generally raise a small brood, and the parents cooperate in caring for the clutch and for the young.

Male bonding behaviour

In early February 2004 the New York Times reported a male pair of chinstrap penguins in the Central Park Zoo in New York City were partnered and even successfully hatched a female chick from an egg. Other penguins in New York have also been reported to be forming same-sex pairs.

This was the basis for the children's picture book And Tango Makes Three. The couple about whom the book was based, Roy and Silo, would see further interesting developments in their relationship when in September 2005, Silo left Roy for a female penguin, only to come back to Roy in a few weeks.

Zoos in Japan and Germany have also documented male penguin couples. The couples have been shown to build nests together and use a stone to replace an egg in the nest. Researchers at Rikkyo University in Tokyo, found twenty such pairs at sixteen major aquariums and zoos in Japan. Bremerhaven Zoo in Germany attempted to break up the male couples by importing female penguins from Sweden and separating the male couples; they were unsuccessful. The zoo director stated the relationships were too strong between the couples.

Classification

ORDER SPHENISCIFORMES

Name

Penguin is thought by some to derive from the Welsh words pen (head) and gwyn (white), applied to the Great Auk, which had a conspicuous white patch between the bill and the eye (although its head was black), or from an island off Newfoundland known as "White Head" due to a large white rock. This may be, however, a false etymology created by Dr John Dee in his book on Prince Madoc of Wales, supposedly one of the discoverers of America. By this Dee hoped to cement Queen Elizabeth I's claim, as a Tudor, to the New World. Penguins live nowhere near Newfoundland, nor do they generally have white heads, however Great Auks did and look remarkably like penguins. According to another theory, the original name was pen-wing, with reference to the rudimentary wings of both Great Auks and penguins. A third theory is that penguin comes from the Latin pinguis (fat). This is a theory, because of two other Germanic languages: Dutch 'pinguïn' and German 'Pinguin' both have the 'i' vowel too. While it has been replaced by an 'e' in the English spelling, it can still be heard. By simply looking at the word's pronunciation and comparing that to the Dutch and German words, one could assume a common Latin borrowing into these Germanic languages - after the first Germanic sound shift (500-200 BC) that makes a PIE 'p' into a 'f', of course. However, a Welsh 'i' is often mutated to an 'e' in the English language so the Welsh origin is still a strong theory.

Penguins and polar bears

Despite what commercials and other sources may show, the likelihood of a meeting between a penguin and a polar bear without human intervention is vanishingly small. This is because the two species are found on opposite hemispheres. Polar bears inhabit the northern hemisphere, while penguins mainly inhabit the southern hemisphere. This is a misconception that is fueled by popular culture such as movies and television. A prominent example of this takes place in a holiday 2005 ad campaign by Coca-Cola featuring the partying penguins and the polar bears watching from afar.

Main article: Penguins in popular culture

Penguins are popular around the world primarily for their unusually upright, waddling pace and (compared to other birds) lack of fear towards humans. Their striking black and white plumage is often likened to a tuxedo suit and generates humourous remarks about the bird being "well dressed".

Perhaps in reaction to this cutesy stereotype, fictional penguins are occasionally presented as grouchy or even sinister. The popular Sanrio character Badtz Maru is an example, being cute yet somewhat surly. The 1960s television cartoon character Tennessee Tuxedo would often escape the confines of his zoo with his partner, Chumley the walrus. Also, the webcomic Fluble features an enormous penguin conspiracy run by numerous diabolical, if often inept, penguins. In the children's movie Madagascar (film), the penguins are cast as spies. In the animated series "Wallace and Gromit" a penguin called Feathers McGraw disguises himself as a chicken with a red rubber glove. Penguins are often portrayed as friendly and smart as well. Another example is in the anime Neon Genesis Evangelion, which features a warm-water penguin named Pen Pen. Tux the penguin is the official mascot for linux.

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References

  • Mayr, G. (2005). "Tertiary plotopterids (Aves, Plotopteridae) and a novel hypothesis on the phylogenetic relationships of penguins (Spheniscidae)". Journal of Zoological Systematics and Evolutionary Research. 43 (1): 61–71.
  • Davis; Lloyd S.; Renner; M. (1995). Penguins . London: T & A D Poyser. ISBN 0-7136-6550-5.
  • Williams; Tony D. (1995). The Penguins - Spheniscidae . Oxford: Oxford University Press. ISBN 0-19-854667-X.

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