The cheetah's chest is deep and its waist is narrow. The coarse, short fur of the cheetah is tan with round black spots measuring from 2 to 3 cm (0.79 to 1.18 in) across, affording it some camouflage while hunting. There are no spots on its white underside, but the tail has spots, which merge to form four to six dark rings at the end. The tail usually ends in a bushy white tuft. The cheetah has a small head with high-set eyes. Black "tear marks" running from the corner of its eyes down the sides of the nose to its mouth keep sunlight out of its eyes and aid in hunting and seeing long distances. Its thin and fragile body make it well-suited to short bursts of high speed, but not to long-distance running.

Agility, rather than raw speed, accounts for much of the cheetah's ability to catch prey. Cheetahs can accelerate four times as fast as a human (thanks to greater muscle power) and can slow down by 14 kilometers per hour in one stride. They can hunt successfully in dense forests.[17]

The adult cheetah weighs from 21 to 72 kg (46 to 159 lb). Its total head-and-body length is from 110 to 150 cm (43 to 59 in), while the tail can measure 60 to 84 cm (24 to 33 in) in length.[18][19][20][21] Cheetahs are 66 to 94 cm (26 to 37 in) tall at the shoulder. Males tend to be slightly larger than females and have slightly bigger heads, but there is not a great variation in cheetah sizes and it is difficult to tell males and females apart by appearance alone. Compared to a similarly sized leopard, the cheetah is generally shorter-bodied, but is longer tailed and taller (it averages about 90 cm (35 in) tall) and so it appears more streamlined.

Some cheetahs have a rare fur pattern mutation of larger, blotchy, merged spots. Known as "king cheetahs," they were once thought to constitute a separate subspecies but are in fact African cheetahs; their unusual fur pattern is the result of a single recessive gene.[22] The "king cheetah" has only been seen in the wild a handful of times, but it has been bred in captivity.



Comparative illustration of a leopard (left) and cheetah (right)
The cheetah's paws have semi-retractable claws (known only in three other cat species: the fishing cat, the flat-headed cat and the Iriomote cat), offering extra grip in its high-speed pursuits. The ligament structure of the cheetah's claws is the same as those of other cats; it simply lacks the sheath of skin and fur present in other varieties, and therefore, with the exception of the dewclaw, the claws are always visible. The dewclaw is much shorter and straighter than that of other cats.

Adaptations that enable the cheetah to run as fast as it does include large nostrils that allow for increased oxygen intake, and an enlarged heart and lungs that work together to circulate oxygen efficiently. During a typical chase, its respiratory rate increases from 60 to 150 breaths per minute.[12] While running, in addition to having good traction due to its semi-retractable claws, the cheetah uses its tail as a rudder-like means of steering[citation needed] to allow it to make sharp turns, necessary to outflank prey animals that often make such turns to escape.

Unlike true big cats of subfamily Pantherinae, the cheetah can purr as it inhales, but cannot roar. By contrast, the big cats can roar but cannot purr, except while exhaling. The cheetah is still considered by some to be the smallest of the big cats. While it is often mistaken for the leopard, the cheetah does have distinguishing features, such as the aforementioned long "tear-streak" lines that run from the corners of its eyes to its mouth, and spots that are not "rosettes". The thinner body frame of the cheetah is also very different from that of the leopard.

File:Cheetahs on the Edge (Director's Cut).ogv 

A documentary video shot at 1200fps documenting the movement of a cheetah over a set run
The cheetah is a vulnerable species. Of all the big cats, it is the least able to adapt to new environments. It has always proved difficult to breed in captivity, although recently a few zoos have managed to succeed at this. One technique has been to introduce a dog as a playmate and guard dog to enable a captive cheetah to feel less threatened.[23]

Once widely hunted for its fur, the cheetah now suffers more from the loss of both habitat and prey.

The cheetah was formerly considered to be particularly primitive among the cats and to have evolved approximately 18 million years ago. However, new research suggests the last common ancestor of all 40 existing species of felines lived more recently than about 11 million years ago. The same research indicates that the cheetah, while highly derived morphologically, is not of particularly ancient lineage, having separated from its closest living relatives (Puma concolor, the cougar, and Puma yaguarondi, the jaguarundi) around five million years ago.[15] These felids have not changed appreciably since they first appeared in the fossil record.