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Giraffe[1]
File:Giraffa camelopardalis
A male Angolan Giraffe (G. c. angolensis) close to Namutoni, Namibia
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Family: Giraffidae
Genus: Giraffa
Species: G. camelopardalis
Binomial name
Giraffa camelopardalis
Linnaeus, 1758

The giraffe (Giraffa camelopardalis) is an African even-toed ungulate mammal, the tallest of all land-living animal species, and the largest ruminant. The giraffe's scientific name, which is similar to its antiquated English name of camelopard, refers to its irregular patches of color on a light background, which bear a token resemblance to a leopard's spots. The average mass for an adult male giraffe is 1,200 kilograms (2,600 lb) while the average mass for an adult female is 830 kilograms (1,800 lb).[3][4] It is approximately 4.3 metres (14 ft) to 5.2 metres (17 ft) tall, although the tallest male recorded stood almost 6 metres (20 ft).[3][4]

The giraffe is related to other even-toed ungulates, such as deer and cattle, but is placed in a separate family, the Giraffidae, consisting of only the giraffe and its closest relative, the okapi. Its range extends from Chad in Central Africa to South Africa. Giraffes usually inhabit savannas, grasslands, or open woodlands. However, when food is scarce they will venture into areas with denser vegetation. They prefer areas with plenty of acacia growth. They will drink large quantities of water when available, which enables them to live for extended periods in dry, arid areas. The giraffe's fur also works as a chemical defence, and is full of antibiotics and parasite repellents which gives the animal a characteristic scent. Old males are sometimes nicknamed "stink bulls". There are at least eleven main smelly chemicals in the fur, although it is indole and 3-methylindole which is responsible for most of their smell. Because the males have a stronger odour than the females, it is also assumed that it has a sexual function as well.[5]

Contents

Etymology

The species name camelopardalis (camelopard) is derived from its early Roman name, where it was described as having characteristics of both a camel and a leopard.[6] The English word camelopard first appeared in the 14th century and survived in common usage well into the 19th century. The Afrikaans language retained it. The Arabic word الزرافة ziraafa or zurapha, meaning "assemblage" (of animals), or just "tall", was used in English from the sixteenth century on, often in the Italianate form giraffa.

Taxonomy and evolution

The giraffe is one of only two living species of the family Giraffidae, along with the okapi. The family was once much more extensive, with numerous other species. The giraffids evolved from a 3 metres (9.8 ft) tall antelope-like mammal that roamed Europe and Asia some 30–50 million years ago.[7]

The earliest known giraffid was Climacoceras, which still resembled deer, having large antler-like ossicones. It first appeared in the early Miocene epoch. Later examples include the genera Palaeotragus and Samotherium, which appeared in the early to mid-Miocene. They were both tall at the shoulder, and had developed the simple, unbranched ossicones of modern giraffids, but still had relatively short necks.[8]

From the late Pliocene onwards, the variety of giraffids drastically declined, until only the two surviving species remained. The modern genus Giraffa evolved during the Pliocene epoch, and included a number of other long-necked species, such as Giraffa jumae, that do not survive today.[8] Alan Turner proposes, in the 2004 book Evolving Eden, that giraffe ancestors initially had a dark coat with pale spots, and that the spots gradually became star-shaped, before eventually forming the reticulated pattern found today.[9] The modern species, Giraffa camelopardalis, appeared during the Pleistocene 1 million years ago.[citation needed]

The evolution of the long necks of giraffes has been the subject of much debate. The standard story is that they were evolved to allow the giraffes to browse vegetation that was out of the reach of other herbivores in the vicinity, giving them a competitive advantage.[8] However, an alternative theory proposes that the long necks evolved as a secondary sexual characteristic, giving males an advantage in "necking" contests (see below) to establish dominance and obtain access to sexually receptive females. This theory notes that giraffes frequently feed from relatively low-lying shrubs, and that the necks of males are significantly longer than those of females.[10] However, this theory is not universally accepted, and some of the data supporting it has recently been challenged, lending support to the original proposal that neck length is related to browsing habits.[11] Although giraffes can feed as low as 0.5 m and as high as 6 m off the ground, it appears that they are most efficient feeding at 2–4 m.[12]

Subspecies

Different authorities recognize different numbers of subspecies, differentiated by colour and pattern variations and range.[1][2][13] Some of these subspecies may prove to in fact be separate species.[2] The subspecies recognized by various authorities include:

  • Reticulated Giraffe or Somali Giraffe (G. c. reticulata) – large, polygonal liver-coloured spots outlined by a network of bright white lines. The blocks may sometimes appear deep red and may also cover the legs. Range: northeastern Kenya, Ethiopia, Somalia.
  • Angolan Giraffe or Smoky Giraffe (G. c. angolensis) – large spots and some notches around the edges, extending down the entire lower leg. Range: Angola, Zambia.
  • Kordofan Giraffe (G. c. antiquorum) – smaller, more irregular spots that cover the inner legs. Range: western and southwestern Sudan, Cameroon.
  • Maasai Giraffe or Kilimanjaro Giraffe (G. c. tippelskirchi) – jagged-edged, vine-leaf shaped spots of dark chocolate on a yellowish background. Range: central and southern Kenya, Tanzania.
  • Nubian Giraffe (G. c. camelopardalis) – large, four-sided spots of chestnut brown on an off-white background and no spots on inner sides of the legs or below the hocks. Range: eastern Sudan, northeast Congo.
  • Rothschild Giraffe or Baringo Giraffe or Ugandan Giraffe (G. c. rothschildi) – deep brown, blotched or rectangular spots with poorly defined cream lines. Hocks may be spotted. Range: Uganda, north-central Kenya.
  • South African Giraffe (G. c. giraffa) – rounded or blotched spots, some with star-like extensions on a light tan background, running down to the hooves. Range: South Africa, Namibia, Botswana, Zimbabwe, Mozambique.
  • Thornicroft Giraffe or Rhodesian Giraffe (G. c. thornicrofti) – star-shaped or leafy spots extend to the lower leg. Range: eastern Zambia.
  • West African Giraffe or Nigerian Giraffe (G. c. peralta) – numerous pale, yellowish red spots. Range: Niger.

Some scientists regard Kordofan and West African Giraffes as a single subspecies; similarly with Nubian and Rothschild's Giraffes, and with Angolan and South African Giraffes. Further, some scientists regard all populations except the Masai Giraffes as a single subspecies. By contrast, scientists have proposed four other subspecies — Cape Giraffe (G. c. capensis), Lado Giraffe (G. c. cottoni), Congo Giraffe (G. c. congoensis), and Transvaal Giraffe (G. c. wardi) — but none of these is widely accepted.

Though giraffes of these populations interbreed freely under conditions of captivity, suggesting that they are subspecific populations, genetic testing published in 2007[1] has been interpreted to show that there may be at least six species of giraffe that are reproductively isolated and not interbreeding, even though no natural obstacles, like mountain ranges or impassable rivers block their mutual access. In fact, the study found that the two giraffe populations that live closest to each other— the reticulated giraffe (G. camelopardalis reticulata) of north Kenya, and the Masai giraffe (G. c. tippelskirchi) in south Kenya— separated genetically between 0.13 and 1.62 million years BP, judging from genetic drift in nuclear and mitochondrial DNA.

The implications for conservation of as many as eleven such cryptic species and sub-species were summarised by David Brown for BBC News: "Lumping all giraffes into one species obscures the reality that some kinds of giraffe are on the brink. Some of these populations number only a few hundred individuals and need immediate protection."[2]

Anatomy and morphology

, Oklahoma City, Oklahoma.]] Male giraffes are up to 5.5 metres (18 ft) tall at the horn tips, and weigh between 800 and 1,930 kilograms (1,800 and 4,300 lb). Females are between 4 and 4.5 metres (13 and 14.8 ft) tall and weigh between 550 and 1,180 kilograms (1,200 and 2,600 lb). The coat is made up of brown blotches or patches separated by lighter hair. Each giraffe has a unique coat pattern.[3] Wild giraffes have a lifespan close to 13 years while those in captivity live up to 25 years.[4]

Horns

Both sexes have horns, although the horns of a female are smaller. The prominent horns are formed from ossified cartilage, and are called ossicones. The appearance of horns is a reliable method of identifying the sex of giraffes, with the females displaying tufts of hair on the top of the horns, whereas males' horns tend to be bald on top — an effect of necking in combat. Males sometimes develop calcium deposits which form bumps on their skull as they age, which can give the appearance of up to three additional horns.[5]

Legs and pacing

Giraffes also have slightly elongated forelegs, about 10% longer than their hind legs, and can reach a sprint speed of up to 60 km/h (37 mph).[6] It cannot sustain a lengthy chase. Its leg length compels an unusual gait with the left legs moving together followed by right (similar to pacing) at low speed, and the back legs crossing outside the front at high speed. When hunting adult giraffes, lions try to knock the lanky animal off its feet and pull it down. Giraffes are difficult and dangerous prey. The giraffe defends itself with a powerful kick. A single well-placed kick from an adult giraffe can shatter a lion's skull or break its spine. Lions are the only predators which pose a serious threat to an adult giraffe.

Neck

Giraffes have long necks which they use to browse tree leaves. The neck has seven highly lengthened vertebrae, otherwise the usual number of vertebrae for a mammal. However, some zoologists claim there are eight.[7] Moreover, the vertebrae are separated by very flexible joints, the base of the neck has spines which project upward to form a hump over the shoulders and anchor muscles hold the neck upright.

Circulatory system

Modifications to the giraffe's structure have evolved, particularly to the circulatory system. A giraffe's heart, which can weigh up to 10 kg (22 lb) and measure about 60 cm (2 ft) long, must generate approximately double the normal blood pressure for an average large mammal to maintain blood flow to the brain. In the upper neck, a complex pressure-regulation system called the rete mirabile prevents excess blood flow to the brain when the giraffe lowers its head to drink. Conversely, the blood vessels in the lower legs are under great pressure (because of the weight of fluid pressing down on them). In other animals such pressure would force the blood out through the capillary walls; giraffes, however, have a very tight sheath of thick skin over their lower limbs which maintains high extravascular pressure in the same way as a pilot's g-suit.

Behaviour

Social structure and breeding habits

Female giraffes associate in groups of a dozen or so members, occasionally including a few younger males. Younger males tend to live in "bachelor" herds, with older males often leading solitary lives. While research from the 1970s concluded that giraffes did not socialize, later research found that giraffes did form moderate attachments to other giraffes, with giraffes spending 15% of their time grazing with the giraffes they are close to and only 5% of their time grazing with giraffes who are strangers.[8] Giraffe groups with young tend to feed in more open areas, presumably to provide better visibility to detect predators. This may reduce their feeding efficiency.[9]

Reproduction is polygamous, with a few older males impregnating the fertile females in a herd. Male giraffes determine female fertility by tasting the female's urine in order to detect estrus, in a multi-step process known as the Flehmen response.

Giraffes will mingle with the other herbivores in the African bush. Their company is beneficial, since they are tall enough to have a much wider scope of an area and will watch for predators.

Reproduction

Giraffe gestation lasts between 400 and 460 days, after which a single calf is normally born, although twins occasionally occur.[10] The mother gives birth standing up and the embryonic sack usually bursts when the baby falls to the ground. Newborn giraffes are about 1.8 m (6 ft) tall.

Within a few hours of being born, calves can run around and are indistinguishable from a week-old calf; however, for the first two weeks, they spend most of their time lying down, guarded by the mother. The young can fall prey to lions, leopards, spotted hyenas, and wild dogs. It has been speculated that their characteristic spotted pattern provides a certain degree of camouflage. Only 25 to 50% of giraffe calves reach adulthood; the life expectancy is between 20 and 25 years in the wild and 28 years in captivity.[11]

Necking

Male giraffes often engage in necking, which has been described as having various functions. One of these is combat. Battles can be fatal, but are more often less severe, generally ending when one giraffe surrenders to the other. The longer the neck, and the heavier the head at the end of the neck, the greater the force a giraffe is able to deliver in a blow. It has also been observed that males that are successful in necking have greater access to estrous females, so the length of the neck may be a product of sexual selection.[12]

After a necking duel, a giraffe can land a powerful blow with his head — occasionally knocking a male opponent to the ground. These fights rarely last more than a few minutes or end in physical harm.

Another function of necking is sexual, in which two males caress and court each other, leading up to mounting and climax. Such interactions between males are more frequent than heterosexual coupling.[13] In one study, up to 94% of observed mounting incidents took place between two males. The proportion of same sex activities varied between 30 and 75%, and at any given time one in twenty males were engaged in non-combative necking behaviour with another male. Only 1% of same-sex mounting incidents occurred between females.[14]

Diet

File:Giraffe feeding,
Giraffe extending its tongue to feed

The giraffe browses on the twigs of trees, preferring trees of the genera Acacia, Commiphora and Terminalia, and also eats grass and fruit.[15][16] The tongue is tough due to the giraffe's diet, which can include tree thorns. In Southern Africa, giraffes feed on all acacias, especially Acacia erioloba, and possess a specially adapted tongue and lips that are tough enough to withstand the vicious thorns of this plant. A giraffe can eat 65 pounds (29 kg) of leaves and twigs daily, but can survive on just 15 pounds (6.8 kg).[16] The giraffe requires less food than typical grazing animals because the foliage it eats has more concentrated nutrition and it has a more efficient digestive system.[15] During the wet season, food is abundant and giraffes disperse widely, but during the dry season they need to congragate around evergreen trees and bushes.[15] As a ruminant, it first chews its food, then swallows for processing and then visibly regurgitates the semi-digested cud up their necks and back into the mouth, in order to chew again. This process is usually repeated several times for each mouthful. The giraffe can survive without water for extended periods.[16] A giraffe will clean off any bugs that appear on its face with its extremely long tongue (about 45 centimetres (18 in)).

Sleeping

The giraffe has one of the shortest sleep requirements of any mammal, which is between ten minutes and two hours in a 24-hour period, averaging 1.9 hours per day.[17]

Communication

Although generally quiet and non-vocal, giraffes have been heard to make various sounds. Courting males will emit loud coughs.[citation needed] Females will call their young by whistling or bellowing. Calves will bleat, moo, or make mewing sounds. In addition, giraffes will grunt, snort, hiss, or make strange flute-like sounds. Recent research has shown evidence that the animal communicates at an infrasound level.[18]

Stereotypic behavior

Many animals when kept in captivity, such as in zoos, display abnormal behaviours. Such unnatural behaviours are known as stereotypic behaviours.[19] In particular, giraffes show distinct patterns of stereotypic behaviours when removed from their natural environment. Due to a subconscious response to suckle milk from their mother, something which many human-reared giraffes and other captive animals do not experience, giraffes resort instead to excessive tongue use on inanimate objects.[20]

Human interactions

Conservation

, Kenya.]] Overall, the giraffe is regarded as "Least Concern" from a conservation perspective by the International Union for Conservation of Nature (IUCN).[21] However, at least one subspecies, the West African or Nigerian Giraffe (G. c. peralta), has been classified as endangered.[22]

Giraffes are hunted for their tails, hides and meat.[16] The tails are used as good luck charms, thread and flyswatters.[16] In addition, habitat destruction also hurts the giraffe. In the Sahel trees are cut down for firewood and to make way for livestock. Normally, giraffes are able to cope with livestock since they feed in the trees above their heads. The giraffe population is shrinking in West Africa. However, the populations in eastern and southern Africa are stable and, due to the popularity of privately owned game ranches and sanctuaries (i.e. Bour-Algi Giraffe Sanctuary), are expanding. The giraffe is a protected species in most of its range. The total African giraffe population has been estimated to range from 110,000 to 150,000. Kenya (45,000), Tanzania (30,000), and Botswana (12,000), have the largest national populations.[23]

Scientific inspiration

Giraffes have been used as examples for introducing ideas in evolution, especially to illustrate the ideas of Lamarck. Lamarck believed that the giraffe's long neck developed as a result of ancestral giraffe's reaching to browse on the leaves of tall trees.[24]

The coat patterns of several species of giraffe have been modelled using reaction-diffusion mechanisms.[25]

In art and culture

to China during the Ming Dynasty.[26]]]

Giraffes can be seen in paintings, including the famous painting of a giraffe which was taken from Somalia to China in 1414. The giraffe was placed in a Ming Dynasty zoo.[27] At one point the giraffe was associated with the mythical Qilin, and a derivative of that name (kirin) is still used as the word for giraffe in Japan, Taiwan, and Korea.

The Medici giraffe was a giraffe presented to Lorenzo de' Medici in 1486. It caused a great stir on its arrival in Florence, being reputedly the first living giraffe to be seen in Italy since the days of Ancient Rome. Another famous giraffe, called Zarafa, was brought from Africa to Paris in the early 1800s and kept in a menagerie for 18 years.

Giraffe is a novel by the author J. M. Ledgard. The work concerns a true incident in which 49 giraffes were slaughtered in the Czech Republic (then Czechoslovakia) in 1975 following the suspected outbreak of disease amongst the group. The novel contains extensive information about the species, including the long history of European fascination with the beast and its captivity in zoos.

Notable fictional giraffes include:


References

  1. ^ Brown, D. M., et al. (2007). "Extensive Population Genetic Structure in the Giraffe". BMC Biology 5 (57): 57. doi:10.1186/1741-7007-5-57. PMID 18154651. PMC 2254591. http://www.biomedcentral.com/1741-7007/5/57. Retrieved 2009-03-04. 
  2. ^ Lever, A. (2007-12-21). "Not one but 'six giraffe species'". BBC News. http://news.bbc.co.uk/1/hi/sci/tech/7156146.stm. Retrieved 2009-03-04. 
  3. ^ Estes, R. (1991). The Behavior Guide to African Mammals. University of California Press. pp. 202–207. ISBN 0-520-08085-8. 
  4. ^ "Woodland Park Zoo euthanizes ailing giraffe". Seattle Times. 2009-11-17. http://seattletimes.nwsource.com/html/localnews/2010287334_webgiraffe17m.html. Retrieved 2009-12-18. 
  5. ^ "San Diego Zoo's Animal Bytes: Giraffe". http://www.sandiegozoo.org/animalbytes/t-giraffe.html. Retrieved 2009-03-04. 
  6. ^ Garland, T; Janis CM (1993). "Does metatarsal/femur ratio predict maximal running speed in cursorial mammals?" (pdf). Journal of Zoology 229 (1): 133–151. doi:10.1111/j.1469-7998.1993.tb02626.x. http://www.biology.ucr.edu/people/faculty/Garland/GarlandJanis1993.pdf. 
  7. ^ Solounias, N. (1999) The remarkable anatomy of the giraffe's neck. J. Zool., Lond. 247:257-268 PDF
  8. ^ Grandin, Temple; Johnson, Catherine (2005). Animals in Translation. New York, New York: Scribner. p. 129. ISBN 0743247698. 
  9. ^ {{broken ref |msg=Cite error: Invalid tag; no text was provided for refs named {{{1|sexdiff}}}; see Help:Cite errors/Cite error references no text |cat=Pages with broken reference names}}
  10. ^ "Mammal Guide - Giraffe". Animal Planet. http://animal.discovery.com/guides/mammals/habitat/tropgrassland/giraffe.html. Retrieved 2009-03-07. 
  11. ^ "Giraffe", Encyclopedia of Animals.
  12. ^ Robert E. Simmons and Lue Scheepers: Winning by a neck: Sexual selection in the evolution of giraffe. The American Naturalist, 148 (1996): pp. 771-786.
  13. ^ Coe, M.J. (1967). "Necking" behavior in the giraffe." Journal of Zoology, London 151: 313-321.
  14. ^ Bruce Bagemihl, Biological Exuberance: Animal Homosexuality and Natural Diversity, St. Martin's Press, 1999; pp.391-393.
  15. ^ a b c Kingdon, J. (1997). The Kingdon Field Guide to African Mammals. Academic Press. pp. 339–344. ISBN 0-12-408355-2. 
  16. ^ a b c d e "Giraffe". African Wildlife Foundation. http://www.awf.org/content/wildlife/detail/giraffe. Retrieved 2009-03-07. 
  17. ^ "Science & Nature - Human Body and Mind - What is sleep". BBC. 2004-11-01. http://www.bbc.co.uk/science/humanbody/sleep/articles/whatissleep.shtml. Retrieved 2009-03-08. 
  18. ^ "Infrasound From the Giraffe". Animalvoice.com. http://www.animalvoice.com/Giraffe.htm. Retrieved 2009-03-08. 
  19. ^ Jentz, D.C. & A.B. Gull 1978. Towards a definition of abnormal activity: stereotypic behaviours in captive primates. Mamm. Ecol. 12: 145–154.
  20. ^ Harrison, J.C, Q.F. George & C.C. Cronk 2001. Stereotypic behaviour in zoo animals. J. Zoo Sc. 23: 71–86.
  21. ^ {{broken ref |msg=Cite error: Invalid tag; no text was provided for refs named {{{1|iucn}}}; see Help:Cite errors/Cite error references no text |cat=Pages with broken reference names}}
  22. ^ Fennessy, J. & Brown, D. (2008). Giraffa camelopardalis ssp. peralta. In: IUCN 2008. IUCN Red List of Threatened Species. Downloaded on 13 March 2009.
  23. ^ East, R. 1998, in: African Antelope Database 1998. IUCN/SSC Antelope Specialist Group Report.
  24. ^ Holdrege, C. (2003). "The Giraffe's Short Neck". In Context (The Nature Institute) (10): 14–19. http://www.natureinstitute.org/pub/ic/ic10/giraffe.htm. Retrieved 2009-04-06. 
  25. ^ Walter, Marcelo; Fournier,, Alain and Menevaux, Daniel (2001) Integrating shape and pattern in mammalian models in SIGGRAPH '01: Proceedings of the 28th annual conference on Computer graphics and interactive techniques. pp. 317-326 doi:http://doi.acm.org/10.1145/383259.383294
  26. ^ "Zheng He (Cheng Ho)". Hyperhistory.net. http://www.hyperhistory.net/apwh/bios/b3zhenghe.htm. Retrieved 2008-09-01. 
  27. ^ Laufer, Berthold (1928). The Giraffe in History and Art. Field Museum of Natural History, Chicago. http://www.archive.org/details/giraffeinhistory27lauf. 

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Giraffe[1]
File:Giraffe
Conservation status
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Family: Giraffidae
Genus: Giraffa
Species: G. camelopardalis
Binomial name
Giraffa camelopardalis
Linnaeus, 1758

The giraffe (Giraffa camelopardalis) is an African even-toed ungulate mammal, the tallest of all land-living animal species, and the largest ruminant. It is covered in large, irregular patches of yellow to black fur separated by white, off-white, or dark yellowish brown background. The average mass for an adult male giraffe is 1,191 kilograms (2,630 lb) while the average mass for an adult female is 828 kilograms (1,830 lb).[3][4] It is approximately 4.3 metres (14 ft) to 5.2 metres (17 ft) tall, although the tallest male recorded stood almost 6 metres (20 ft).[3][4]

The giraffe is related to deer and cattle, but is placed in a separate family, the Giraffidae, consisting of only the giraffe and its closest relative, the okapi. Its range extends from Chad in Central Africa to South Africa.

Giraffes usually inhabit savannas, grasslands, or open woodlands. However, when food is scarce they will venture into areas with denser vegetation. They prefer areas with plenty of acacia growth. They will drink large quantities of water when available which enables them to live for extended periods in dry, arid areas.

Contents

Etymology

The species name camelopardalis (camelopard) is derived from its early Roman name, where it was described as having characteristics of both a camel and a leopard.[5] The English word camelopard first appeared in the 14th century and survived in common usage well into the 19th century. The Afrikaans language retained it. The Arabic word الزرافة ziraafa or zurapha, meaning "assemblage" (of animals), or just "tall", was used in English from the sixteenth century on, often in the Italianate form giraffa.

Taxonomy and evolution

The giraffe is one of only two living species of the family Giraffidae, along with the okapi. The family was once much more extensive, with numerous other species. The giraffids evolved from a 3 metres (9.8 ft) tall antelope-like mammal that roamed Europe and Asia some 30-50 million years ago.[6]

The earliest known giraffid was Climacoceras, which still resembled deer, having large antler-like ossicones. It first appeared in the early Miocene epoch. Later examples include the genera Palaeotragus and Samotherium, which appeared in the early to mid-Miocene. They were both tall at the shoulder, and had developed the simple, unbranched ossicones of modern giraffids, but still had relatively short necks.[7]

From the late Pliocene onwards, the variety of giraffids drastically declined, until only the two surviving species remained. The modern genus Giraffa evolved during the Pliocene epoch, and included a number of other long-necked species, such as Giraffa jumae, that do not survive today.[7] Alan Turner proposes, in the 2004 book Evolving Eden, that giraffe ancestors initially had a dark coat with pale spots, and that the spots gradually became star-shaped, before eventually forming the reticulated pattern found today.[8] The modern species, Giraffa camelopardalis, appeared during the Pleistocene 1 million years ago.[citation needed]

The evolution of the long necks of giraffes has been the subject of much debate. The standard story is that they were evolved to allow the giraffes to browse vegetation that was out of the reach of other herbivores in the vicinity, giving them a competitive advantage.[7] However, an alternative theory proposes that the long necks evolved as a secondary sexual characteristic, giving males an advantage in "necking" contests (see below) to establish dominance and obtain access to sexually receptive females. This theory notes that giraffes frequently feed from relatively low-lying shrubs, and that the necks of males are significantly longer than those of females.[9] However, this theory is not universally accepted, and some of the data supporting it has recently been challenged, lending support to the original proposal that neck length is related to browsing habits.[10]

Subspecies

Different authorities recognize different numbers of subspecies, differentiated by colour and pattern variations and range.[1][2][11] Some of these species may prove to in fact be separate species.[2] The subspecies recognized by various authorities include:

  • Reticulated or Somali Giraffe (G. c. reticulata) — large, polygonal liver-coloured spots outlined by a network of bright white lines. The blocks may sometimes appear deep red and may also cover the legs. Range: northeastern Kenya, Ethiopia, Somalia.
  • Angolan or Smoky Giraffe (G. c. angolensis) — large spots and some notches around the edges, extending down the entire lower leg. Range: Angola, Zambia.
  • Kordofan Giraffe (G. c. antiquorum) — smaller, more irregular spots that cover the inner legs. Range: western and southwestern Sudan, Cameroon.
File:Giraffa camelopardalis tippelskirchi
G. c. tippelskirchi has distinctive jagged-edged spots
  • Masai or Kilimanjaro Giraffe (G. c. tippelskirchi) — jagged-edged, vine-leaf shaped spots of dark chocolate on a yellowish background. Range: central and southern Kenya, Tanzania.
  • Nubian Giraffe (G. c. camelopardalis) — large, four-sided spots of chestnut brown on an off-white background and no spots on inner sides of the legs or below the hocks. Range: eastern Sudan, northeast Congo.
  • Rothschild Giraffe or Baringo Giraffe or Ugandan Giraffe (G. c. rothschildi) — deep brown, blotched or rectangular spots with poorly defined cream lines. Hocks may be spotted. Range: Uganda, north-central Kenya.
  • South African Giraffe (G. c. giraffa) — rounded or blotched spots, some with star-like extensions on a light tan background, running down to the hooves. Range: South Africa, Namibia, Botswana, Zimbabwe, Mozambique.
  • Thornicroft or Rhodesian Giraffe (G. c. thornicrofti) — star-shaped or leafy spots extend to the lower leg. Range: eastern Zambia.
  • West African or Nigerian Giraffe (G. c. peralta) — numerous pale, yellowish red spots. Range: Niger.

Some scientists regard Kordofan and West African Giraffes as a single subspecies; similarly with Nubian and Rothschild's Giraffes, and with Angolan and South African Giraffes. Further, some scientists regard all populations except the Masai Giraffes as a single subspecies. By contrast, scientists have proposed four other subspecies — Cape Giraffe (G. c. capensis), Lado Giraffe (G. c. cottoni), Congo Giraffe (G. c. congoensis), and Transvaal Giraffe (G. c. wardi) — but none of these is widely accepted.

Though giraffes of these populations interbreed freely under conditions of captivity, suggesting that they are subspecific populations, genetic testing published in 2007[12] has been interpreted to show that there may be at least six species of giraffe that are reproductively isolated and not interbreeding, even though no natural obstacles, like mountain ranges or impassable rivers block their mutual access. In fact, the study found that the two giraffe populations that live closest to each other— the reticulated giraffe (G. camelopardalis reticulata) of north Kenya, and the Masai giraffe (G. c. tippelskirchi) in south Kenya— separated genetically between 0.13 and 1.62 million years BP, judging from genetic drift in nuclear and mitochondrial DNA.

The implications for conservation of as many as eleven such cryptic species and sub-species were summarised by David Brown for BBC News: "Lumping all giraffes into one species obscures the reality that some kinds of giraffe are on the brink. Some of these populations number only a few hundred individuals and need immediate protection."[13]

Anatomy and morphology

]] Male giraffes are up to 5.5 metres (18 ft) tall at the horn tips, and weigh between 800 and 1,930 kilograms (1,800 and 4,300 lb). Females are between 4 and 4.5 metres (13 and 15 ft) tall and weigh between 550 and 1,180 kilograms (1,200 and 2,600 lb). The coat is made up of brown blotches or patches separated by lighter hair. Each giraffe has a unique coat pattern.[14]

Horns

Both sexes have horns, although the horns of a female are smaller. The prominent horns are formed from ossified cartilage, and are called ossicones. The appearance of horns is a reliable method of identifying the sex of giraffes, with the females displaying tufts of hair on the top of the horns, whereas males' horns tend to be bald on top — an effect of necking in combat. Males sometimes develop calcium deposits which form bumps on their skull as they age, which can give the appearance of up to three additional horns.[15]

]]

Neck

Giraffes have long necks which they use to browse tree leaves. The neck has seven highly lengthened vertebrae, otherwise the usual number of vertebrae for a mammal. However, some zoologists claim there are eight.[16] Moreover, the vertebrae are separated by very flexible joints, the base of the neck has spines which project upward to form a hump over the shoulders and anchor muscles hold the neck upright.

Legs and pacing

Giraffes also have slightly elongated forelegs, about 10% longer than their hind legs. The pace of the giraffe is an amble, though when pursued it can run extremely fast, up to 55 km/h.[17] It cannot sustain a lengthy chase. Its leg length compels an unusual gait with the left legs moving together followed by right (similar to pacing) at low speed, and the back legs crossing outside the front at high speed. When hunting adult giraffes, lions try to knock the lanky animal off its feet and pull it down. Giraffes are difficult and dangerous prey. The giraffe defends itself with a powerful kick. A single well-placed kick from an adult giraffe can shatter a lion's skull or break its spine. Lions are the only predators which pose a serious threat to an adult giraffe.

Circulatory system

Modifications to the giraffe's structure have evolved, particularly to the circulatory system. A giraffe's heart, which can weigh up to 10 kg (22 lb) and measure about 60 cm (2 ft) long, must generate approximately double the normal blood pressure for an average large mammal to maintain blood flow to the brain. In the upper neck, a complex pressure-regulation system called the rete mirabile prevents excess blood flow to the brain when the giraffe lowers its head to drink. Conversely, the blood vessels in the lower legs are under great pressure (because of the weight of fluid pressing down on them). In other animals such pressure would force the blood out through the capillary walls; giraffes, however, have a very tight sheath of thick skin over their lower limbs which maintains high extravascular pressure in the same way as a pilot's g-suit.

Behaviour

Social structure and breeding habits

Female giraffes associate in groups of a dozen or so members, occasionally including a few younger males. Younger males tend to live in "bachelor" herds, with older males often leading solitary lives. Reproduction is polygamous, with a few older males impregnating all the fertile females in a herd. Male giraffes determine female fertility by tasting the female's urine in order to detect estrus, in a multi-step process known as the Flehmen response.

Giraffes will mingle with the other herbivores in the African bush. Their company is beneficial, since they are tall enough to have a much wider scope of an area and will watch for predators.

Reproduction

Giraffe gestation lasts between 400 and 460 days, after which a single calf is normally born, although twins occasionally occur.[18] The mother gives birth standing up and the embryonic sack usually bursts when the baby falls to the ground. Newborn giraffes are about 1.8 m (6 ft) tall.

Within a few hours of being born, calves can run around and are indistinguishable from a week-old calf; however, for the first two weeks, they spend most of their time lying down, guarded by the mother. The young can fall prey to lions, leopards, spotted hyenas, and wild dogs. It has been speculated that their characteristic spotted pattern provides a certain degree of camouflage. Only 25 to 50% of giraffe calves reach adulthood; the life expectancy is between 20 and 25 years in the wild and 28 years in captivity (Encyclopedia of Animals).

Necking

As noted above, males often engage in necking, which has been described as having various functions. One of these is combat. Battles can be fatal, but are more often less severe. The longer the neck, and the heavier the head at the end of the neck, the greater the force a giraffe is able to deliver in a blow. It has also been observed that males that are successful in necking have greater access to estrous females, so the length of the neck may be a product of sexual selection.[19]

After a necking duel, a giraffe can land a powerful blow with his head — occasionally knocking a male opponent to the ground. These fights rarely last more than a few minutes or end in physical harm.

Another function of necking is sexual, in which two males caress and court each other, leading up to mounting and climax. Such interactions between males are more frequent than heterosexual coupling.[20] In one study, up to 94% of observed mounting incidents took place between two males. The proportion of same sex activities varied between 30 and 75%, and at any given time one in twenty males were engaged in non-combative necking behaviour with another male. Only 1% of same-sex mounting incidents occurred between females.[21]

tongues to extend their reach]]

Diet

The giraffe browses on the twigs of trees, preferring trees of the genera Acacia, Commiphora and Terminalia, and also eats grass and fruit.[11][22] The tongue is tough due to the giraffe's diet, which can include tree thorns. In Southern Africa, giraffes feed on all acacias, especially Acacia erioloba, and possess a specially-adapted tongue and lips that are tough enough to withstand the vicious thorns of this plant. A giraffe can eat 65 pounds (29 kg) of leaves and twigs daily, but can survive on just 15 pounds (6.8 kg).[22] The giraffe requires less food than typical grazing animals because the foliage it eats has more concentrated nutrition and it has a more efficeint digestive system.[11] During the wet season, food is abundant and giraffes disperse widely, but during the dry season they need to congragate around evergreen trees and bushes.[11] As a ruminant, it first chews its food, then swallows for processing and then visibly regurgitates the semi-digested cud up their necks and back into the mouth, in order to chew again. This process is usually repeated several times for each mouthful. The giraffe can surivive without water for extended periods.[22] A giraffe will clean off any bugs that appear on its face with its extremely long tongue (about 45 centimetres (18 in)).

Sleeping

The giraffe has one of the shortest sleep requirements of any mammal, which is between ten minutes and two hours in a 24-hour period, averaging 1.9 hours per day.[23]

, Providence, Rhode Island]]

Communication

Although generally quiet and not vocal, giraffes have been heard to make various sounds. Courting males will emit loud coughs. Females will call their young by whistling or bellowing. Calves will bleat, moo, or make mewing sounds. In addition, giraffes will grunt, snort, hiss, or make strange flute-like sounds. Recent research has shown evidence that the animal communicates at an infrasound level.[24]

Stereotypic behavior

Many animals when kept in captivity, such as in zoos, display abnormal behaviours. Such unnatural behaviours are known as stereotypic behaviours.[25] In particular, giraffes show distinct patterns of stereotypic behaviours when removed from their natural environment. Due to a subconscious response to suckle milk from their mother, something which many human-reared giraffes and other captive animals do not experience, giraffes resort instead to excessive tongue use on inanimate objects.[26]

Due to the obvious social and cultural discomfort associated with the addition of milk delivery devices, animal enclosures are often enriched with other stimuli, such as food and mental distractions (toys, scent markings etc.). This operates as a distraction, removing the giraffe’s focus from its instinctual tendencies towards suckling, resulting in tongue lolling and licking of objects in close proximity.

Human interactions

Conservation

, Kenya.]] Overall, the giraffe is regarded as "Least Concern" from a conservation perspective by the International Union for Conservation of Nature (IUCN).[2] However, at least one subspecies, the West African or Nigerian Giraffe (G. c. peralta), has been classified as endangered.[27]

Giraffes are hunted for their tails, hides and meat.[22] The tails are used as good luck charms, thread and flyswatters.[22] In addition, habitat destruction also hurts the giraffe. In the Sahel trees are cut down for firewood and to make way for livestock. Normally, giraffes are able to cope with livestock since they feed in the trees above their heads. The giraffe population is shrinking in West Africa. However, the populations in eastern and southern Africa are stable and, due to the popularity of privately-owned game ranches and sanctuaries (i.e. Bour-Algi Giraffe Sanctuary), are expanding. The giraffe is a protected species in most of its range. The total African giraffe population has been estimated to range from 110,000 to 150,000. Kenya (45,000), Tanzania (30,000), and Botswana (12,000), have the largest national populations.[28]

Scientific inspiration

Giraffes have been used as examples for introducing ideas in evolution, especially to illustrate the ideas of Lamarck. Lamarck believed that the giraffe's long neck developed as a result of ancestral giraffe's reaching to browse on the leaves of tall trees.[29]

The coat patterns of several species of giraffe have been modelled using reaction-diffusion mechanisms.[30]

In art and culture

Giraffes can be seen in paintings, including the famous painting of a giraffe which was taken from Africa to China in 1414. The giraffe was placed in a Ming Dynasty zoo.[31]

The Medici giraffe was a giraffe presented to Lorenzo de' Medici in 1486. It caused a great stir on its arrival in Florence, being reputedly the first living giraffe to be seen in Italy since the days of Ancient Rome. Another famous giraffe, called Zarafa, was brought from Africa to Paris in the early 1800s and kept in a menagerie for 18 years.

Giraffe is a novel by the author J. M. Ledgard. The work concerns a true incident in which 49 giraffes were slaughtered in the Czech Republic (then Czechoslovakia) in 1975 following the suspected outbreak of disease amongst the group. The novel contains extensive information about the species, including the long history of European fascination with the beast and its captivity in zoos.

Notable fictional giraffes include:

References

  1. ^ a b Wilson, D. E., and Reeder, D. M. (eds), ed (2005). Mammal Species of the World (3rd edition ed.). Johns Hopkins University Press. ISBN 0-801-88221-4. http://www.bucknell.edu/msw3/browse.asp?id=14200476. 
  2. ^ a b c d Fennessy, J. & Brown, D. (2008). Giraffa camelopardalis. 2008 IUCN Red List of Threatened Species. IUCN 2008. Retrieved on 13 March 2009.
  3. ^ a b Dagg, A. I. (1971). Mammalian Species 5. pp. 1–8. 
  4. ^ a b Skinner, J. D. & Smithers, R. H. M. (1990). The mammals of the southern African subregion. Pretoria: University of Pretoria. 
  5. ^ David. "Camelopard". Dave's Mythical Creatures and Places. http://www.eaudrey.com/myth/camelopard.htm. Retrieved on 2009-03-04. 
  6. ^ "Familiar Strangers". International Wildlife 23: 6–10. 1993. 
  7. ^ a b c Savage, R. J. G. & Long, M. R. (1986). Mammal Evolution: an illustrated guide. New York: Facts on File. pp. 228–229. ISBN 0-8160-1194-X. 
  8. ^ Turner, A. & Anton, M. (2004). Evolving Eden. New York: Columbia University Press. p. 149. ISBN 0-231-11944-5. 
  9. ^ Simmons, R. E. & Scheepers, L. (1996). "Winning by a Neck: Sexual Selection in the Evolution of Giraffe". The American Naturalist 148 (5): 771–786. http://bill.srnr.arizona.edu/classes/182/Giraffe/WinningByANeck.pdf. 
  10. ^ Cameron, E. Z. & du Toit, J. T. (2007). "Winning by a Neck: Tall Giraffes Avoid Competing with Shorter Browsers". American Naturalist 169 (1): 130–135. doi:10.1086/509940. 
  11. ^ a b c d Kingdon, J. (1997). The Kingdon Field Guide to African Mammals. Academic Press. pp. 339–344. ISBN 0-12-408355-2. 
  12. ^ Brown, D. M., et al. (2007). "Extensive Population Genetic Structure in the Giraffe". BMC Biology 5 (57). doi:10.1186/1741-7007-5-57. http://www.biomedcentral.com/1741-7007/5/57. Retrieved on 2009-03-04. 
  13. ^ Lever, A. (2007-12-21). "Not one but 'six giraffe species'". BBC News. http://news.bbc.co.uk/1/hi/sci/tech/7156146.stm. Retrieved on 2009-03-04. 
  14. ^ Estes, R. (1991). The Behavior Guide to African Mammals. University of California Press. pp. 202–207. ISBN 0-520-08085-8. 
  15. ^ "San Diego Zoo's Animal Bytes: Giraffe". http://www.sandiegozoo.org/animalbytes/t-giraffe.html. Retrieved on 2009-03-04. 
  16. ^ Solounias, N. (1999) The remarkable anatomy of the giraffe's neck. J. Zool., Lond. 247:257-268 PDF
  17. ^ Gitau, P. (2008). "Articlebase The Kenyan Giraffe". http://www.articlesbase.com/destinations-articles/the-kenyan-giraffe-639715.html. Retrieved on 2009-03-04. 
  18. ^ "Mammal Guide - Giraffe". Animal Planet. http://animal.discovery.com/guides/mammals/habitat/tropgrassland/giraffe.html. Retrieved on 2009-03-07. 
  19. ^ Robert E. Simmons and Lue Scheepers: Winning by a neck: Sexual selection in the evolution of giraffe. The American Naturalist, 148 (1996): pp. 771-786.
  20. ^ Coe, M.J. (1967). "Necking" behavior in the giraffe." Journal of Zoology, London 151: 313-321.
  21. ^ Bruce Bagemihl, Biological Exuberance: Animal Homosexuality and Natural Diversity, St. Martin's Press, 1999; pp.391-393.
  22. ^ a b c d e "Giraffe". African Wildlife Foundation. http://www.awf.org/content/wildlife/detail/giraffe. Retrieved on 2009-03-07. 
  23. ^ "Science & Nature - Human Body and Mind - What is sleep". BBC. 2004-11-01. http://www.bbc.co.uk/science/humanbody/sleep/articles/whatissleep.shtml. Retrieved on 2009-03-08. 
  24. ^ "Infrasound From the Giraffe". Animalvoice.com. http://www.animalvoice.com/Giraffe.htm. Retrieved on 2009-03-08. 
  25. ^ Jentz, D.C. & A.B. Gull 1978. Towards a definition of abnormal activity: stereotypic behaviours in captive primates. Mamm. Ecol. 12: 145–154.
  26. ^ Harrison, J.C, Q.F. George & C.C. Cronk 2001. Stereotypic behaviour in zoo animals. J. Zoo Sc. 23: 71–86.
  27. ^ Fennessy, J. & Brown, D. (2008). Giraffa camelopardalis ssp. peralta. 2008 IUCN Red List of Threatened Species. IUCN 2008. Retrieved on 13 March 2009.
  28. ^ East, R. 1998, in: African Antelope Database 1998. IUCN/SSC Antelope Specialist Group Report.
  29. ^ Holdrege, C. (2003). "The Giraffe's Short Neck". The Nature Institute. 14–19. http://www.natureinstitute.org/pub/ic/ic10/giraffe.htm. Retrieved on 2009-04-06. 
  30. ^ Walter, Marcelo; Fournier,, Alain and Menevaux, Daniel (2001) Integrating shape and pattern in mammalian models in SIGGRAPH '01: Proceedings of the 28th annual conference on Computer graphics and interactive techniques. pp. 317-326 doi:http://doi.acm.org/10.1145/383259.383294
  31. ^ Laufer, Berthold (1928). The Giraffe in History and Art. Field Museum of Natural History, Chicago. http://www.archive.org/details/giraffeinhistory27lauf. 

External links



Wiktionary

Up to date as of January 15, 2010

Definition from Wiktionary, a free dictionary

A giraffe
See also Giraffe

Contents

English

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Wikipedia

Etymology

From French giraffe (now girafe), from Arabic زرافة (zarāfah).

Pronunciation

Noun

Singular
giraffe

Plural
giraffes

giraffe (plural giraffes)

  1. A ruminant, of the genus Giraffa, of the African savannah with long legs and highly elongated neck, which make it the tallest living animal; yellow fur patterned with dark spots, often in the form of a network; and two or more short, skin-covered horns.
  2. (Cockney rhyming slang) A laugh.
    Are you having a giraffe?!

Synonyms

Derived terms

Translations

Anagrams


Italian

Noun

giraffe f.

  1. Plural form of giraffa.

Simple English

Giraffe
File:Giraffe
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Artiodactyla
Family: Giraffidae
Genus: Giraffa
Species: G. camelopardalis
Binomial name
Giraffa camelopardalis
Linnaeus, 1758

A giraffe (Giraffa camelopardalis) is an even-toed ungulate mammal from Africa. It is the tallest animal that lives on land. The giraffe and Okapi form the family Giraffidae.

Contents

Appearance

Giraffes can be 4.8 to 5.5 metres / 16 to 18 ft tall and weigh up to 900 kilograms / 2000 pounds. Giraffes have a very long neck and legs. Their fur has a light yellowish or brownish colour with dark patches. Both male and female Giraffes have small horn-like stumps on their head which are covered with skin. They have a long blue tongue, which can be up to 45 cm long. They eat plants and small insects.

Habitat

Giraffes are found in parts of Africa.They live on the savannah, which is the African grassland, or in light woodland. They do not live in thick forests where it is difficult to see predators such as lions approaching.

Life

Giraffes eat mostly leaves from trees, which they can reach because of their long legs and long necks. They can go without water for weeks.

Giraffes live alone or in loose groups. Young male giraffes form small groups until they become mature. Adult males live alone. Females form groups of 4 - 32 animals. When the female is close to giving birth, it leaves the group for a time to give birth to its offspring, and comes back 2-3 weeks after her baby is born.

After a pregnancy of 14-15 months the female gives birth to usually a single baby (which is called "calf"). Giraffes give birth while standing, so the baby falls down 2 meters. Giraffe calfs are already 1.8 m tall and weigh 50 kg. The calf stays with its mother for 1½ years. Young giraffes become mature when they are 4 years old, and they are fully grown when they are 6 years old. Giraffes can become 25 years old, in captivity they can become 35 years old.

More Facts

Giraffes are the tallest animals of all. They have long legs and long necks. There are 7 bones in their necks, the same as in ours. Males can grow to nearly five and a half metres tall, and females to nearly five metres tall.

There are about 9 different sub-species, or breeds, of giraffe. There are only small differences between them. When giraffes of two different sub-species breed, the young are called hybrids (mixed breeds). Of the nine sub-species of giraffe, only one, the Rothchild's, is endangered.

Giraffes have horns called ossicones. These are fur-covered bumps on their skulls, unlike the horns of other animals.Giraffe skin is blotched in patterns of browns and yellows. No two have the same pattern. The different sub-species have different coat patterns.

Look up Giraffa camelopardalis in Wikispecies, a directory of species

krc:Сурахайpcd:Girafe


Citable sentences

Up to date as of December 20, 2010

Here are sentences from other pages on Giraffe, which are similar to those in the above article.








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