Thursday, 6 October 2016

White tiger


The white Bengal tigers are distinctive due to the color of their fur. The white fur caused by a lack of the pigment pheomelanin, which is found in Bengal tigers with orange color fur. When compared to Bengal tigers, the white Bengal tigers tend to grow faster and heavier than the orange Bengal tiger. They also tend to be somewhat bigger at birth, and as fully grown adults. White Bengal tigers are fully grown when they are 2–3 years of age. White male tigers reach weights of 200 to 230 kilograms an can grow up to 3 meters in length. As with all tigers, the white Bengal tiger’s stripes are like fingerprints, with no two tigers having the same pattern. The stripes of the tiger are a pigmentation of the skin; if an individual were to be shaved, its distinctive coat pattern would still be visible. For a white Bengal tiger to be born, both parents must carry the unusual gene for white colouring, which only happens naturally about once in 10,000 births. Dark-striped white individuals are well-documented in the Bengal tiger subspecies (Panthera tigris tigris) as well as having been reported historically in several other subspecies. Currently, several hundred white tigers are in captivity worldwide, with about one hundred being found in India. Their unique white color fur has made them popular in entertainment showcasing exotic animals, and at zoos.White Siberian tigers

White Siberian tigers


The existence of white Siberian tigers has not been scientifically documented, despite occasional unsubstantiated reports of sightings of white tigers in the regions where wild Siberian tigers live. It may be that the white mutation does not exist in the wild Siberian tiger population: no white Siberian tigers have been born in captivity, despite the fact that the subspecies has been extensively bred during the last few decades (with much outbreeding between the different Siberian lineages for purposes of conservation genetics); a recessive allele should occasionally turn up in a homozygous state during such breeding, and in this particular case yield white tigers from normally-colored parents, but no such animals have beenreported.The famous white Siberian tigers found in captivity are actually not pure Siberian tigers. They are instead the result of Siberian tigers breeding with Bengal tigers. The gene for white coating is quite common among Bengal tigers, but the natural birth of a white Bengal tiger is still a very rare occasion in the wild, where white tigers are not bred selectively.


Stripeless white tigers and golden tabby tiger

The white tiger is not considered a tiger subspecies, but rather a hybrid mutant variant of the existing tiger subspecies. If a pure white Siberian tiger were to be born, it would therefore not be selectively bred within the tiger conservation programs. It would, however, probably still be selectively bred outside the program in an effort to create more white Siberian tigers. Due to the popularity of white tigers, they are used to attract visitors to zoos. White tigers are found in zoos in China commonly.Stripeless white tigers and golden tabby tigerA tiger with almost no stripes at The Mirage in Las Vegas.An additional genetic condition can remove most of the striping of a white tiger, making the animal almost pure white. One such specimen was exhibited at Exeter Change in England in 1820, and described by Georges Cuvier as "A white variety of Tiger is sometimes seen, with the stripes very opaque, and not to be observed except in certain angles of light."[3] Naturalist Richard Lydekker said that, "a white tiger, in which the fur was of a creamy tint, with the usual stripes faintly visible in certain parts, was exhibited at the old menagerie at Exeter Change about the year 1820."[4] Hamilton Smith said, "A wholly white tiger, with the stripe-pattern visible only under reflected light, like the pattern of a white tabby cat, was exhibited in the Exeter Change Menagerie in 1820.", and John George Wood stated that, "a creamy white, with the ordinary tigerine stripes so faintly marked that they were only visible in certain lights." Edwin Henry Landseer also drew this tigress in 1824.The modern strain of snow white tigers came from repeated brother–sister matings of Bhim and Sumita at Cincinnati Zoo. The gene involved may have come from a Siberian tiger, via their part-Siberian ancestor Tony. Continued inbreeding appears to have caused a recessive gene for stripelessness to show up. About one fourth of Bhim and Sumita's offspring were stripeless. Their striped white offspring, which have been sold to zoos around the world, may also carry the stripeless gene. Because Tony's genome is present in many white tiger pedigrees, the gene may also be present in other captive white tigers. As a result, stripeless white tigers have appeared in zoos as far afield as theCzech Republic (Liberec), Spain and Mexico. Stage magicians Siegfried & Roy were the first to attempt to selectively breed tigers for stripelessness; they owned snow-white Bengal tigers taken from Cincinnati Zoo (Tsumura, Mantra, Mirage and Akbar-Kabul) and GuadalajaraMexico (Vishnu and Jahan), as well as a stripeless Siberian tiger called Apollo.[5]In 2004, a blue-eyed, stripeless white tiger was born in a wildlife refuge in AlicanteSpain. Its parents are normal orange Bengals. The cub was named Artico ("Arctic").Stripeless white tigers were thought to be sterile until Siegfried & Roy's stripeless white tigress Sitarra, a daughter of Bhim and Sumita, gave birth. Another variation which came out of the white strains were unusually light-orange tigers called "golden tabby tigers". These are probably orange tigers that carry the stripeless white gene as a recessive. Some white tigers in India are very dark, between white and orange.

In captivity


White tigers at the Haifa Zoo, IsraelIndiaWhite tigers are found in many major zoos across India. Nandankanan Zoological ParkOdisha hosts 34 white tigers with the first litter of white tigers born in 1980.[30]AfricaParc de Ben Aknoun is a zoo in the city of Algiers, which houses white tigers of a rare breed. Two females and a male were brought on a flight from Gabon, in July 2014.[31]CaribbeanThe Emperor Valley Zoo in Trinidad and Tobago houses a male (Shere Khan) and female (Rajasi) white tiger. On 10th January 2015, Rajasi gave birth to two cubs, Raja and Rani.[32][33]EuropeJardim Zoológico de Lisboa (the Zoologic Garden of Lisbon) is home to five white tigers, a male and female along with their cubs (one male and two females), all born in the zoo.[34][35] Two Bengal white tigers were born in a zoo in Győr in January 2015.[36]Three Bengal white tigers were born in a zoo in November 2014, in a mini-zoo in KlaipėdaLithuania,[37] and five female Bengal white tigers were born in April 2015.[38][39][40]AmericaThere are two white tigers in captivity at Downtown Aquarium, Houston, under a legal permit by Tilman J. Fertitta. There are three white tigers in Beto Carrero World Park in Brazil.

In popular culture

White Tiger deformedOutside of India, inbred white tigers have been prone to crossed eyes, a condition known as strabismus, an example of which is "Clarence the cross-eyed lion",[10] due to incorrectly routed visual pathways in the brains of white tigers. When stressed or confused, all white tigers cross their eyes. Strabismus is associated with white tigers of mixed Bengal x Siberian ancestry. The only pure-Bengal white tiger reported to be cross-eyed was Mohini's daughter Rewati. Strabismus is directly linked to the white gene and is not a separate consequence of inbreeding.The orange litter-mates of white tigers are not prone to strabismus. Siamese cats and albinos of every species which have been studied all exhibit the same visual pathway abnormality found in white tigers. Siamese cats are also sometimes cross-eyed, as are some albino ferrets. The visual pathway abnormality was first documented in white tigers in the brain of a white tiger called Moni after he died, although his eyes were of normal alignment. The abnormality is that there is a disruption in the optic chiasm. The examination of Moni's brain suggested the disruption is less severe in white tigers than it is in Siamese cats. Because of the visual pathway abnormality, by which some optic nerves are routed to the wrong side of the brain, white tigers have a problem with spatial orientation, and bump into things until they learn to compensate. Some tigers compensate by crossing their eyes. When the neurons pass from the retina to the brain and reach the optic chiasma, some cross and some do not, so that visual images are projected to the wrong hemisphere of the brain. White tigers cannot see as well as normal tigers and suffer from photophobia, like albinos.Other genetic problems include shortened tendons of the forelegs, club foot, kidney problems, arched or crooked backbone and twisted neck. Reduced fertility and miscarriages, noted by ”tiger man” Kailash Sankhala in pure-Bengal white tigers, were attributed to inbreeding depression.[9] A condition known as "star-gazing" (the head and neck are raised almost straight up, as if the affected animal is gazing at the stars), which is associated with inbreeding in big cats, has also been reported in white tigers.[14] Some white tigers born to North American lines have bulldog faces with a snub nose, jutting jaw, domed head and wide-set eyes with an indentation between the eyes. However, some of these traits may be linked to poor diet rather than inbreeding.There was a 450 lb (200 kg) male cross-eyed white tiger at the Pana'ewa Rainforest Zoo in Hawaii, which was donated to the zoo by Las Vegas magician Dirk Arthur.[15] There is a picture of a white tiger which appears to be cross-eyed on just one side in Siegfried & Roy's book Mastering The Impossible. A white tiger, named Scarlett O'Hara, who was Tony's sister, was cross-eyed only on the right side.A male white tiger named Cheytan, a son of Bhim and Sumita born at the Cincinnati Zoo, died at the San Antonio Zoo in 1992 from anaesthesia complications during root canal therapy. It appears that white tigers also react strangely to anaesthesia. The best drug for immobilizing a tiger is CI 744, but a few tigers, white ones in particular, undergo a re-sedation effect 24–36 hours later.[16] This is due to their inability to produce normal tyrosinase, a trait they share with albinos, according tozoo veterinarian David Taylor.  He treated a pair of white tigers from the Cincinnati Zoo at Fritz Wurm's safari park in Stukenbrock, Germany, forsalmonella poisoning, which reacted strangely to the anaesthesia.[17]Mohini was checked for Chédiak-Higashi syndrome in 1960, but the results were inconclusive.[18][19] This condition is similar to albino mutations and causes bluish lightening of the fur color, crossed eyes, and prolonged bleeding after surgery. Also, in the event of an injury, the blood is slow to coagulate. This condition has been observed in domestic cats, but there has never been a case of a white tiger having Chédiak-Higashi syndrome. There has been a single case of a white tiger having central retinal degeneration, reported from the Milwaukee County Zoo, which could be related to reduced pigmentation in the eye. The white tiger in question was a male named Mota on loan from the Cincinnati Zoo.