The liger is a hybrid cross between a male lion (Panthera leo) and a tigress (Panthera tigris). Thus, it has parents with the same genus but of different species. It is distinct from the similar hybrid tiglon. It is the largest of all known cats and extant felines.
Ligers enjoy swimming, which is a characteristic of tigers, and are very sociable like lions. Ligers exist only in captivity because the habitats of the parental species do not overlap in the wild. Historically, when the Asiatic Lion was prolific the territories of lions and tigers did overlap and there are legends of ligers existing in the wild. Notably, ligers typically grow larger than either parent species, unlike tiglons which tend to be about as large a female tiger.
The history of ligers dates to at least the early 19th century in, India Asia. In 1798, Étienne Geoffroy Saint-Hilaire (1772–1844) made a colour plate of the offspring of a lion and a tiger.In 1825, G.B. Whittaker made an engraving of liger cubs born in 1824. parents and their three liger offspring are also depicted with their trainer in a 19th Century painting in the naïve style.
Two liger cubs which had been born in 1837 were exhibited to William IV and to his successor Victoria. On 14 December 1900 and on 31 May 1901, Carl Hagenbeck wrote to zoologist James Cossar Ewart with details and photographs of ligers born at the Hagenbeck's Tierpark in Hamburg in 1897.
In 1935, four ligers from two litters were reared in the Zoological Gardens of Bloemfontein, South Africa. Three of them, a male and two females, were still living in 1953. The male weighed 340 kg (750 lb) and stood a foot and a half (45 cm) taller than a full grown male lion at the shoulder.Although ligers are more commonly found than tiglons today, in At Home In The Zoo (1961), Gerald Iles wrote "For the record I must say that I have never seen a liger, a hybrid obtained by crossing a lion with a tigress. They seem to be even rarer than tigons."
The liger is the largest known cat in the world. Imprinted genes may be a factor contributing to huge liger size. These are genes that may or may not be expressed on the parent they are inherited from, and that occasionally play a role in issues of hybrid growth. For example, in some dog breed crosses, genes that are expressed only when maternally-inherited cause the young to grow larger than is typical for either parent breed. This growth is not seen in the paternal breeds, as such genes are normally "counteracted" by genes inherited from the female of the appropriate breed.
Other big cat hybrids can reach similar sizes; the litigon, a rare hybrid of a male lion and a female tiglon, is roughly the same size as the liger, with a male named Cubanacan (at the Alipore Zoo in India) reaching 363 kg (800 lb). The extreme rarity of these second-generation hybrids may make it difficult to ascertain whether they are larger or smaller, on average, than the liger.
It is erroneously believed that ligers continue to grow throughout their lives due to hormonal issues. It may be that they simply grow far more during their growing years and take longer to reach their full adult size. Further growth in shoulder height and body length is not seen in ligers over 6 years old, same as both lions and tigers. Male ligers also have the same levels of testosterone on average as an adult male lion, yet are azoospermic in accordance with Haldane's rule. In addition, female ligers may also attain great size, weighing approximately 320 kg (705 lb) and reaching 3.05 m (10 ft) long on average, and are often fertile. In contrast, pumapards (hybrids between pumas and leopards) tend to exhibit dwarfism.
