Although tigers are no longer classified into subspecies, many people continue to refer to tigers using their subspecies names, in part because these names refer to where the animals are found. Using this naming system, three subspecies are now extinct. The Caspian tiger once lived in Afghanistan, Iran, Turkey, and the Central Asiatic region of Russia; it became extinct in the 1950s. The Javan tiger once lived on the island of Java and became extinct in the 1970s. The Bali tiger lived on the island of Bali; the last wild Bali tiger was killed in the late 1930s.
Five tiger subspecies are still living. The Amur tiger, also known as the Siberian tiger, lives primarily in the woodlands of eastern Russia. There are more than 400 Amur tigers in the wild and almost 500 in zoos in Russia, Europe, and the United States. The Bengal or Indian tiger primarily lives in India, with some animals found in nearby Nepal, Bangladesh, Bhutan, and Myanmar. There are about 3,000 Bengal tigers in the wild and about 330 in zoos mostly in India. About 500 Sumatran tigers are found only on the island of Sumatra; another 200 live in zoos throughout Indonesia, North America, Europe, and Australia. About 2,000 Indochinese tigers live primarily in the remote mountainous forests of Thailand, as well as in Myanmar, southern China, Cambodia, Laos, Vietnam, and Malaysia; about 60 live in zoos in Asia and the United States. Fewer than 30 South China tigers may still survive in central and eastern China, and fewer than 50 live in Chinese zoos.
Tigers typically reach a shoulder height of 1 m (3 ft) and measure from 2 to 3 m (7 to 10 ft) from head to rear end. The thick, furred tail extends about 1 m. Tigers range in size from the small Sumatrans, in which females weigh 75 to 110 kg (165 to 240 lb) and males weigh 100 to 140 kg (220 to 310 lb), to the largest Bengal tigers, in which females weigh 100 to 160 kg (220 to 350 lb) and males weigh 180 to 258 kg (400 to 570 lb). The largest tigers are the largest of all cats, but since there is much variation in tiger size, some lions are bigger than some tigers.
Tiger fur is short and varies in color from dark orange to reddish brown, with creamy white on the belly, neck, and inside of limbs. Dark brown or black stripes run vertically across the body. Stripe patterns are unique to individual tigers, and like fingerprints in humans, stripes can be used to tell tigers apart. When you see a tiger in the open, its coloration is vivid and striking. But in the dappled light of the forest or in tall grass, the same bold colors make the tiger nearly invisible to prey and to people. The white tigers seen in some zoos are the result of a rare genetic mutation that occurs rarely in the wild.
As carnivores that kill and feed entirely on the flesh of other mammals, tigers have short, powerful jaws with large jaw muscles. They have 30 teeth, 15 on each side of the jaw. Tigers use their large piercing canines to grab and kill prey. Their scissor-like molars slice flesh, and small incisors scrape meat from bones. Like all cats, tigers have a simple digestive system designed to process meat so that the nutrients can be readily absorbed into the bloodstream.
With the exception of white tigers, which have blue eyes, all tigers have yellow eyes. Tigers mainly use vision to find prey. Although tigers see about as well as humans during the day, their large eye openings gather more light than do human eyes, making tiger night vision far superior to that of humans. In addition, a special structure in the tiger’s eye, called the tapetum lucidum, reflects light, making objects appear brighter. Like the eyes of most carnivores, a tiger’s eyes are at the front of the face, giving tigers binocular vision so that they can focus both eyes on a single object. This helps them judge distance accurately, an ability that is important to predators that must secretly approach their prey to just the right distance before charging in for the kill.
Studies suggest that tigers have very good hearing. They can turn their ears toward the source of a sound, enhancing their hearing sensitivity. They also use olfaction (the sense of smell) to hunt prey, but smell is primarily used to communicate with other tigers in an area. The olfactory system receives smell information through the nose, but tigers also have a vomeronasal olfactory system in which smell information reaches the brain through two tiny openings in the roof of the mouth, just behind the upper incisor teeth.
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