The cheetah (Acinonyx jubatus) is a large cat native to Africa and central Iran. It is the fastest land animal, estimated to be capable of running at 80 to 128 km/h (50 to 80 mph) with the fastest reliably recorded speeds being 93 and 98 km/h (58 and 61 mph), and as such has several adaptations for speed, including a light build, long thin legs and a long tail. It typically reaches 67–94 cm (26–37 in) at the shoulder, and the head-and-body length is between 1.1 and 1.5 m (3 ft 7 in and 4 ft 11 in).
The cheetah's closest relatives are the cougar (Puma concolor) and the jaguarundi (Herpailurus yagouaroundi).[20] Together, these three species form the Puma lineage, one of the eight lineages of the extant felids; the Puma lineage diverged from the rest 6.7 mya. The sister group of the Puma lineage is a clade of smaller Old World cats that includes the genera Felis, Otocolobus and Prionailurus.
The oldest cheetah fossils, excavated in eastern and southern Africa, date to 3.5–3 mya; the earliest known specimen from South Africa is from the lowermost deposits of the Silberberg Grotto (Sterkfontein). Though incomplete, these fossils indicate forms larger but less cursorial than the modern cheetah. Fossil remains from Europe are limited to a few Middle Pleistocene specimens from Hundsheim (Austria) and Mosbach Sands (Germany). Cheetah-like cats are known from as late as 10,000 years ago from the Old World. The giant cheetah (A. pardinensis), significantly larger and slower compared to the modern cheetah, occurred in Eurasia and eastern and southern Africa in the Villafranchian period roughly 3.8–1.9 mya. In the Middle Pleistocene a smaller cheetah, A. intermedius, ranged from Europe to China. The modern cheetah appeared in Africa around 1.9 mya; its fossil record is restricted to Africa.
The diploid number of chromosomes in the cheetah is 38, the same as in most other felids. The cheetah was the first felid observed to have unusually low genetic variability among individuals, which has led to poor breeding in captivity, increased spermatozoal defects, high juvenile mortality and increased susceptibility to diseases and infections. A prominent instance was the deadly feline coronavirus outbreak in a cheetah breeding facility of Oregon in 1983 which had a mortality rate of 60%—higher than that recorded for previous epizootics of feline infectious peritonitis in any felid. The remarkable homogeneity in cheetah genes has been demonstrated by experiments involving the major histocompatibility complex (MHC); unless the MHC genes are highly homogeneous in a population, skin grafts exchanged between a pair of unrelated individuals would be rejected. Skin grafts exchanged between unrelated cheetahs are accepted well and heal, as if their genetic makeup were the same.
The low genetic diversity is thought to have been created by two population bottlenecks from c. 100,000 years and c. 12,000 years ago, respectively. The resultant level of genetic variation is around 0.1–4% of average living species, lower than that of Tasmanian devils, Virunga gorillas, Amur tigers, and even highly inbred domestic cats and dogs.
The cheetah is a lightly built, spotted cat characterised by a small rounded head, a short snout, black tear-like facial streaks, a deep chest, long thin legs and a long tail. Its slender, canine-like form is highly adapted for speed, and contrasts sharply with the robust build of the genus Panthera. Cheetahs typically reach 67–94 cm (26–37 in) at the shoulder and the head-and-body length is between 1.1 and 1.5 m (3 ft 7 in and 4 ft 11 in). The weight can vary with age, health, location, sex and subspecies; adults typically range between 21 and 72 kg (46 and 159 lb). Cubs born in the wild weigh 150–300 g (5.3–10.6 oz) at birth, while those born in captivity tend to be larger and weigh around 500 g (18 oz). Cheetahs are sexually dimorphic, with males larger and heavier than females, but not to the extent seen in other large cats. Studies differ significantly on morphological variations among the subspecies.
The coat is typically tawny to creamy white or pale buff (darker in the mid-back portion). The chin, throat and underparts of the legs and the belly are white and devoid of markings. The rest of the body is covered with around 2,000 evenly spaced, oval or round solid black spots, each measuring roughly 3–5 cm (1.2–2.0 in). Each cheetah has a distinct pattern of spots which can be used to identify unique individuals.[62] Besides the clearly visible spots, there are other faint, irregular black marks on the coat. Newly born cubs are covered in fur with an unclear pattern of spots that gives them a dark appearance—pale white above and nearly black on the underside. The hair is mostly short and often coarse, but the chest and the belly are covered in soft fur; the fur of king cheetahs has been reported to be silky. There is a short, rough mane, covering at least 8 cm (3.1 in) along the neck and the shoulders; this feature is more prominent in males. The mane starts out as a cape of long, loose blue to grey hair in juveniles. Melanistic cheetahs are rare and have been seen in Zambia and Zimbabwe. In 1877–1878, Sclater described two partially albino specimens from South Africa.
Sharply contrasting with the big cats in its morphology, the cheetah shows several adaptations for prolonged chases to catch prey at some of the fastest recorded speeds. Its light, streamlined body makes it well-suited to short, explosive bursts of speed, rapid acceleration, and an ability to execute extreme changes in direction while moving at high speed. The large nasal passages, accommodated well due to the smaller size of the canine teeth, ensure fast flow of sufficient air, and the enlarged heart and lungs allow the enrichment of blood with oxygen in a short time. This allows cheetahs to rapidly regain their stamina after a chase. During a typical chase, their respiratory rate increases from 60 to 150 breaths per minute. Moreover, the reduced viscosity of the blood at higher temperatures (common in frequently moving muscles) could ease blood flow and increase oxygen transport. While running, in addition to having good traction due to their semi-retractable claws, cheetahs use their tail as a rudder-like means of steering that enables them to make sharp turns, necessary to outflank antelopes which often change direction to escape during a chase. The protracted claws increase grip over the ground, while paw pads make the sprint more convenient over tough ground. The limbs of the cheetah are longer than what is typical for other cats its size; the thigh muscles are large, and the tibia and fibula are held close together making the lower legs less likely to rotate. This reduces the risk of losing balance during runs, but compromises the ability to climb. The highly reduced clavicle is connected through ligaments to the scapula, whose pendulum-like motion increases the stride length and assists in shock absorption. The extension of the vertebral column can add as much as 76 cm (30 in) to the stride length.
The cheetah is a carnivore that hunts small to medium-sized prey weighing 20 to 60 kg (44 to 132 lb), but mostly less than 40 kg (88 lb). Its primary prey are medium-sized ungulates. They are the major component of the diet in certain areas, such as Dama and Dorcas gazelles in the Sahara, impala in the eastern and southern African woodlands, springbok in the arid savannas to the south and Thomson's gazelle in the Serengeti. Smaller antelopes like the common duiker are a frequent prey in the southern Kalahari. Larger ungulates are typically avoided, though nyala, whose males weigh around 120 kg (260 lb), were found to be the major prey in a study in the Phinda Game Reserve. In Namibia cheetahs are the major predators of livestock. The diet of the Asiatic cheetah consists of chinkara, desert hare, goitered gazelle, urial, wild goats and livestock; in India cheetahs used to prey mostly on blackbuck. There are no records of cheetahs killing humans. Cheetahs in the Kalahari have been reported feeding on citron melons for their water content.
Prey preferences and hunting success vary with the age, sex and number of cheetahs involved in the hunt and on the vigilance of the prey. Generally only groups of cheetahs (coalitions or mother and cubs) will try to kill larger prey; mothers with cubs especially look out for larger prey and tend to be more successful than females without cubs. Individuals on the periphery of the prey herd are common targets; vigilant prey which would react quickly on seeing the cheetah are not preferred.
