Color Variation of Tiger

Color Variation of Tiger

            The orange colored tiger with black stripes is, of course, the most prevalent. There are different shades of orange ranging from almost yellow to dark burnt orange. The stripes also vary in shade, size and abundance. Some tigers will have dark, wide stripes while some have fewer stripes that are narrower. It is interesting to note that every stripe pattern is unique. No two tigers are marked the same, much like a person's fingerprints.

            Color and striping is controlled by gene groups that are inherited from the parent's genes, the same as hair color in humans. A person may have dark hair and that would be the trait they most likely would pass on to their children, especially if both parents have the same color gene. If one parent has a dark hair, and the other has blond hair, the child will usually have dark hair because the gene for dark hair is dominant. In order for the child to have blonde hair, the parent with dark hair must also have a recessive gene for blonde hair. Then the child has a 50/50 chance to have either color hair. Recessive genes are what cause different color variations - in tigers as well as people. It is what causes a white tiger to be born from two standard colored parents.

Orange Tiger

            The orange colouring is the most common color of tiger. Every subspecies of tiger can be orange. Whereas some of the more exotic colours are limited to certain subspecies.

White Tiger

            A white tiger is caused by the homozygous occurrence of a recessive allele in the genome. Estimations show that around one in 10,000 wild Bengal tiger births will result in a white tiger. The white tiger is not considered a tiger subspecies, but rather a mutant variant of the existing tiger subspecies.

Snow White Tiger

            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.  The modern strain of snow white tigers came from repeated brother–sister mating of Bhim and Sumita. The gene involved may have come from a Siberian tiger; continued inbreeding appears to have caused a recessive gene for stripelessness to show up.

Golden Tabby Tiger

            It is sometimes referred to as the strawberry tiger due to the strawberry blonde coloration. A golden tabby tiger is one with an extremely rare color variation caused by a recessive gene and is currently only found in captive tigers. Like the white tiger, it is a color form and not a separate species. In the case of the golden tiger, this is the wide band gene; while the white tiger is due to the color inhibitor (chinchilla) gene. There are currently believed to be fewer than 30 of these rare tigers in the world. The golden tiger's white coat and gold patches make it stand out from the norm. Their striping is much paler than usual and may fade into spots or large prominent patches. Golden tigers also tend to be larger and, due to the effect of the gene on the hair shaft, have softer fur than their orange relatives.

Maltese Tiger

            The Maltese tiger, or blue tiger, is a semi-hypothetical coloration morph of a tiger, reported mostly in the Fujian Province of China. It is said to have bluish fur with dark grey stripes. Most of the Maltese tigers reported have been of the South Chinese subspecies. The South Chinese tiger today is critically endangered, and the "blue" alleles may be wholly extinct. Blue tigers have also been reported in Korea, home of Siberian tigers. It is suggested that blue tigers possessed two different pairs of recessive alleles - the non-agouti (s/s), and the dilute (d/d) which combine to produce a solid blue-grey colour as found in domestic cats such as the British Blue and Russian Blue.

Black Tiger

            A black tiger is a rare colour variant of the tiger and is not a distinct species or geographic subspecies. There are reports and one painting (now lost) of pure black non-striped tigers (true melanistic tigers). Most black mammals are due to the non-agouti mutation. Agouti refers to the ticking of each individual hair. In certain light, the pattern still shows up because the background color is less dense than the colour of the markings.

            So-called black tigers are due to pseudo-melanism. Pseudo-melanistic tigers have thick stripes so close together that the tawny background is barely visible between stripes. Such tigers are said to be getting more common due to inbreeding. They are also said to be smaller than normal tigers, perhaps also due to inbreeding or because large black leopards are misidentified as black tigers.

There are reports that one of the three white tigers born in Vandalur zoo in June 2010 seems to have changed its colors — most of its body and legs are now black.

References

          http://www.tigerhaven.org/page.asp?page=6&p=Education%20and%20Reference

          http://www.tigerhomes.org/animal/backstage/tiger-color-variations.cfm

          http://en.wikipedia.org/wiki/Tiger

The Arabian Oryx

            At one time extinct in the wild, this desert antelope can once again be seen wandering the dry Arabian Peninsula. The Arabian oryx is an antelope that is highly specialised for its harsh desert environment. The bright white coat reflects the sun’s rays and the hooves are splayed and shovel-like, providing a large surface area with which to walk on the sandy ground. The legs are brown in colour, with white bands on the ankles, and there are also brown markings on the face, on the bridge of the nose, the cheeks and a triangular patch on the forehead. Arabian oryx of both sexes have magnificent straight, ringed horns that can reach up to 68 centimetres in length; those of the female are thinner and longer than the male. Males have a tuft of hair on the throat, and the tails of both sexes are tufted at the ends and dark brown/black on the lower half. Arabian oryx calves are brown with markings on their tail and knees, gaining adult markings by six months.

Status

            The Arabian oryx is classified as Vulnerable (VU) on the IUCN Red List, and listed on Appendix I of CITES.

Range

            Once widespread on the Arabian Peninsula, reaching north into Israel, Jordan, Iraq, Syria and Sinai in Egypt. The last wild oryx was shot in 1972 and the species persisted only in captivity for a decade. Thanks to re-introduction efforts, wild populations now occur in Israel, Oman and Saudi Arabia, and it is likely that, with additional re-introduction programs currently taking place, this range will increase into other countries within the Arabian Peninsula. The Arabian Oryx formerly occurred through most of the Arabian Peninsula, north to Kuwait and Iraq. The species' range had already contracted by the early years of the 20th century and the decline accelerated thereafter. Before 1920, oryx distribution was separated into areas over 1,000 km apart: a northern population in and around the Nafud, and a larger southern population in the Rub Al Khali and the plains of central-southern Oman. Oryx disappeared from the north in the 1950s. In the south, their range steadily decreased due to hunting, and by the 1960s oryx were restricted to parts of central and southern Oman. The last wild individuals were probably shot in 1972 on the Jiddat al Harasis.

            Arabian Oryx have been reintroduced to Oman (Arabian Oryx Sanctuary, from 1982); Saudi Arabia (Mahazat as-Sayd Reserve, 2,244 km² from 1990; Uruq Bani Ma’arid Reserve, 12,000 km² from 1995), Israel (three sites in the Northern Arava and Negev Desert, from 1997); United Arab Emirates (Arabian Oryx Reserve, Abu Dhabi, from 2007); and Jordan (Wadi Rum, beginning 2009).

            Reintroductions in Kuwait, Iraq and Syria have also been proposed. There is a small introduced population on Hawar Island, Bahrain and large semi-managed populations at several sites in Qatar and UAE.

Regionally extinct: Egypt (Sinai); Iraq; Jordan; Kuwait; Syrian Arab Republic; United Arab Emirates; Yemen

Reintroduced: Israel; Oman; Saudi Arabia

Introduced: Bahrain; Qatar

Habitat

            Inhabits the arid plains and deserts of Arabia, where temperatures even in the shade can reach as much as 50ºC in the summer months.

Biology

            Arabian oryx are gregarious animals forming herds containing five to thirty individuals. The herds increase in size in good conditions, however, in poor conditions the group size is usually composed of a male, a couple of females and their young. Other males adopt a more solitary existence and hold large territories. These antelope seem to be able to detect rainfall from a great distance and have an almost nomadic way of life, travelling vast areas in search of precious new growth after intermittent rains. Females give birth to a single calf once a year if conditions are good; births can occur in any month and calves are weaned after three and a half months of age.

            These antelope graze on grasses and herbs and will also take roots and tubers; they can go without direct water sources for long periods of time. Most activity occurs in the early morning and late evening with groups resting in the shade during the searing midday heat. Using their front hooves, oryx excavate depressions in the ground, which allow them to lie in cooler sand, and provide some protection against the fierce desert winds.

Threat

            The Bedouin people of the Arabian Peninsula traditionally hunted Arabian oryx for their meat and hides. The total decimation of the species did not occur until after the Second World War however, with the availability of firearms and motorised transport, and the demand for sport hunting. The species became extinct in the wild in 1972 when the last recorded animal was shot. Following the success of re-introduced herds during the 1990s, poaching once again has become a serious threat and has devastated the Oman population.

Conservation

            The rescue of the Arabian oryx began in early 1960s when Fauna and Flora International had the foresight to capture wild oryx and transfer them to Phoenix Zoo in Arizona. Operation Oryx, as it became known, succeeded in establishing a large captive herd in the USA that could later be used for re-introductions. The first herds were released in Oman at Jaaluni in the Jiddat-al-Harasis in 1982, with more populations subsequently established in Israel and Saudi Arabia . Over the years the wild population has grown, and in 2008 was estimated to number 1,100 individuals. The most recent conservation efforts for the Arabian oryx have taken place in the Emirate of Abu Dhabi, where a release program that was begun in 2007 has released around 100 animals into the wild. The United Arab Emirates government is also funding re-introductions of this species into Jordan and is also considering releases into Yemen. Currently, an inter-governmental body known as The Coordinating Committee for the Conservation of the Arabian Oryx oversees the coordination of conservation efforts for this species within the Arabian Peninsula. Despite the unfortunate poaching problems affecting the Oman population, the re-introduction of the Arabian oryx represents a remarkable conservation success story and an example of what international cooperation can achieve.

References

          http://www.iucnredlist.org/apps/redlist/details/15569/0

            http://www.ultimateungulate.com/artiodactyla/oryx_leucoryx.html

          http://en.wikipedia.org/wiki/Arabian_Oryx

The Blue Whale

            The blue whale (Balaenoptera musculus) is a marine mammal belonging to the suborder of baleen whales (called Mysticeti). At 30 metres (98 ft) in length and 180 metric tons (200 short tons) or more in weight, it is the largest known animal to have ever existed. There are at least three distinct subspecies, B. m. musculus of the North Atlantic and North Pacific, B. m. intermedia (Antarctic Blue Whale) of the Southern Ocean and B. m. brevicauda (also known as the pygmy blue whale) found in the Indian Ocean and South Pacific Ocean. B. m. indica, found in the Indian Ocean, may be another subspecies. As with other baleen whales, its diet consists almost exclusively of small crustaceans known as krill.

Status: The blue whale is classified as Endangered (EN) on the IUCN Red List. It is listed on Appendix I of CITES and Appendix I of the Convention on Migratory Species. Subspecies: Antarctic blue whale, Balaenoptera musculus intermedia, is classified as Critically Endangered (CR); and the pygmy blue whale, Balaenoptera musculus brevicauda, is classified as Data Deficient (DD).

Population: The global population of blue whales is uncertain, but based on the above information; the global total for the species is plausibly in the range 10,000-25,000, corresponding to about 3-11% of the 1911 population size.

Description: The blue whale is the largest animal to have ever lived, being almost as big as a Boeing 737 and even larger than the biggest dinosaurs. The largest recorded length for a blue whale is 33.5 metres, although most individuals vary between 24 and 27 metres. The heart of this monstrous whale is actually around the size of a Volkswagen Beetle.

            Like other rorquals (members of the family Balaenopteridae), the blue whale has a long, somewhat tapered and streamlined body, with the head making up less than one-fourth of its total body length. The rostrum (upper part of the head) is very broad and flat and almost U-shaped, with a single ridge that extends just forward of the blowhole to the tip of the snout. The body is smooth and relatively free of parasites, although a few barnacles may attach to the edge of the tail fluke, the tips of the flippers and to the small, triangular dorsal fin. There is a row of 300 to 400 black baleen plates on each side of the mouth, and approximately 90 throat grooves extend to the navel, which allows the throat to expand enormously during feeding.

            The blow (or spout) of this species is the biggest amongst all whales, the slender upright column of air rising up to nine meters. Blue whales in the Northern Hemisphere are generally smaller than those in the Southern Ocean. The female may be up to 10 metres longer than the male.

            Despite its common name, the blue whale is actually greyish-blue, with a mottled effect that is visible in some lights and can allow individuals to be identified. The underside often has a yellowish tinge, especially on whales living in polar waters, which is caused by microscopic algae called ‘diatoms’ and led to early whalers giving this species the nickname ‘sulphur bottom whale’.

Range: The blue whale is found in every ocean except the Arctic, with a range that extends from the periphery of drift-ice in polar seas to the tropics, although it is absent from some seas such as the Mediterranean, Okhotsk and Bering. It follows a seasonal migration pattern between summering and wintering areas, although some individuals may remain in certain areas year-round. The species’ range can be loosely organised into three main populations: one in the North Atlantic, one in the North Pacific, and another in the southern Hemisphere.

                               

            In the Antarctic region, which formerly supported the largest blue whale population, the blue whale occurs from the Antarctic Polar Front up to and into the ice in the summer, and is thought to migrate equator-wards before winter. In the North Atlantic the summer distribution of the blue whale extends from the Scotian Shelf to the Davis Strait in Canada, eastwards to Iceland, the Denmark Strait and Svalbard, and north to the ice edge. The winter distribution of the blue whale in the North Atlantic is poorly known, but it is thought that in the past the blue whale was widely distributed in the southern half of the North Atlantic in the winter.

            The blue whale occurs in the eastern Pacific from southern Chile to Costa Rica, where it is present year-round. In the North Pacific, it is found from the coast of Oregon to the Kurile Islands and north to the Aleutian Islands. In the past the blue whale was regularly caught off southern Japan and the Korean peninsula, but it has not been seen there in recent years.

Habitat: The blue whale inhabits the open ocean, where it is found most frequently along the continental shelf edge and near polar ice. It feeds at both the surface and at depth, undertaking diurnal vertical migrations as it follows its krill prey to depths of at least 100 metres.

            Poleward movements in the spring allow the blue whale to take advantage of high prey abundances in the summer, while movement towards the subtropics in the autumn allows the blue whale to reduce its energy expenditure while fasting, avoid ice entrapment and breed in warmer waters.

Biology: The blue whale usually occurs alone or in groups of two or three, but occasionally large groups of up to 60 may form in areas of high food abundance. It feeds mainly on shrimp-like krill, which are filtered through the baleen plates. During feeding, large volumes of water and food can be taken into the mouth because the pleated grooves in the throat expand. As the mouth closes, water is expelled through the baleen plates, which trap the food on the inside to be swallowed. During the summer feeding season, the blue whale gorges itself, consuming an astounding 4 tonnes or more each day, meaning it may eat up to 40 million krill a day.

            The blue whale reaches sexual maturity at 7 to 10 years of age, when it will mate with several partners during winter and early spring. A single calf is produced after a gestation period of 10 to 11 months and weaned at the summer feeding grounds, when it is approximately seven months old. During the nursing period, the calf consumes around 100 gallons of the mother’s fat rich-milk and grows an incredible one and a half inches in length each day, with a weight gain of 90 kilograms per day. The inter-birth period for female blue whales is probably two to three years, although this may have decreased recently in response to the low population densities.

            The blue whale produces louder calls than any other animal on earth. Communication occurs via a variety of low frequency sounds and clicks. The male blue whale is capable of producing particularly long calls, which have been well studied and appear to have functions in sensing the environment, prey detection, communication and male display. The call of the blue whale reaches levels up to 188 decibels. This extraordinarily loud whistle can be heard for hundreds of miles underwater. Theoretical calculations by Roger Payne and Douglas Webb (from the 1970's) predicted that the loudest whale sounds might be transmitted across an entire ocean. The blue whale is much louder than a jet, which reaches only 140 decibels.

Threat: Because of its enormous size and speed, the blue whale was largely safe from early whalers, who could not pursue it in open boats with hand harpoons. However, the advent of the exploding harpoon gun in 1868 allowed for the commercial exploitation of this species, with the whaling industry particularly focusing on the blue whale after 1900. The slaughter peaked in 1931, when over 29,000 were killed in one season. After that, blue whales became so scarce that the whalers turned to other species. 

          More than 360,000 blue whales were taken by whaling fleets in the Southern Hemisphere from 1904 to 1967, and the Antarctic and North Atlantic populations were probably depleted to the low hundreds by the time whaling ceased. The total global blue whale population has declined by at least 70 percent, and possibly as much as 90 percent, over the last three generations, with the formerly very large Antarctic population declining over the same period by as much as 97 percent.

            Although commercial whaling of the blue whale is now banned, its population is so small that any further mortalities may severely impact on the survival of the species. It is still subject to a number of threats including ship strikes, noise and chemical pollution, and net entanglement. The remote distribution of some blue whale populations probably makes them less vulnerable to human impacts than some other cetacean species, but local populations that inhabit waters with significant levels of human activity, such as the Gulf of St. Lawrence, may be particularly vulnerable to these threats.

Conservation: Hunting of the blue whale was banned in 1966, although some illegal soviet whaling persisted for several years after. No blue whales have been deliberately caught since 1978. However, this protection almost came too late for the blue whale, and recovery has been extremely slow. Only in the last few years have there been signs that numbers may be increasing. Today, there are an estimated 10,000 to 25,000 blue whales surviving worldwide, which represents around 3 to 11 percent of the total pre-commercial exploitation population. All international trade in the blue whale is further prohibited by its listing on Appendix I of the Convention on International Trade in Endangered Species (CITES) and on Appendix I of the Convention on Migratory Species (CMS or the Bonn Convention).

            The blue whale occurs in a number of Marine Protected Areas throughout its range that is aimed at protecting the whole marine ecosystem, as well as whale sanctuaries in the Antarctic, Indian and Southern Oceans. Several countries have also implemented research and conservation programmes for this species, much of which is coordinated by the International Whaling Commission, and these include identifying areas of critical habitat, investigating species abundance and distribution, and mitigating the threats to the species.

References:

          http://en.wikipedia.org/wiki/Blue_whale

            http://www.enchantedlearning.com/subjects/whales/species/Bluewhale.shtml

            http://www.blue-whale.info/Reproduction_of_Blue_whale.html

            http://www.animalinfo.org/species/cetacean/balamusc.htm

            http://www.antarctica.gov.au/about-antarctica/wildlife/animals/whales/blue-whale