Source: World Wild Life
The giant panda (Ailuropoda melanoleuca), also known as the panda bear or simply panda, is a bear species endemic to China. It is characterised by its white coat with black patches around the eyes, ears, legs and shoulders. Its body is rotund; adult individuals weigh 100 to 115 kg (220 to 254 lb) and are typically 1.2 to 1.9 m (3 ft 11 in to 6 ft 3 in) long. It is sexually dimorphic, with males being typically 10 to 20% larger than females. A thumb is visible on its forepaw, which helps in holding bamboo in place for feeding. It has large molar teeth and expanded temporal fossa to meet its dietary requirements. It can digest starch and is mostly herbivorous with a diet consisting almost entirely of bamboo and bamboo shoots.
For many decades, the precise taxonomic classification of the giant panda was under debate because it shares characteristics with both bears and raccoons.[11] In 1985, molecular studies indicated that the giant panda is a true bear, part of the family Ursidae.[12][13] These studies show it diverged about 19 million years ago from the common ancestor of the Ursidae;[14] it is the most basal member of this family and equidistant from all other extant bear species.[14][15]
Two subspecies of giant panda have been recognized on the basis of distinct cranial measurements, colour patterns, and population genetics
The nominate subspecies, A. m. melanoleuca, consists of most extant populations of the giant panda. These animals are principally found in Sichuan and display the typical stark black and white contrasting colours.[17] The Qinling panda, A. m. qinlingensis,[18] is restricted to the Qinling Mountains in Shaanxi at elevations of 1,300–3,000 m (4,300–9,800 ft). The typical black and white pattern of Sichuan giant pandas is replaced with a light brown and white pattern.[16] The skull of A. m. qinlingensis is smaller than its relatives, and it has larger molars.[19]The giant panda has a body shape typical of bears. It has black fur on its ears, limbs, shoulders and around the eyes. The rest of the animal's coat is white.[32] The bear's distinctive coloration appears to serve as camouflage in both winter and summer environments as they do not hibernate. The white areas serve as camouflage in snow, while the black shoulders and legs conceal them in shade.[33] Studies in the wild have found that when viewed from a distance, the panda displays disruptive coloration, while up close, they rely more on blending in.[34] The black ears may be used to display aggression,[33] while the eye patches might facilitate them identifying one another.[33][35] The giant panda's thick, woolly coat keeps it warm in the cool forests of its habitat.[32]
Despite its taxonomic classification as a carnivoran, the giant panda's diet is primarily herbivorous, with approximately 99% of its diet consisting of bamboo.[48] However, the giant panda still has the digestive system of a carnivore, as well as carnivore-specific genes,[49] and thus derives little energy and little protein from the consumption of bamboo. The ability to break down cellulose and lignin is very weak, and their main source of nutrients comes from starch and hemicelluloses. The most important part of their bamboo diet is the shoots, that are rich in starch and have up to 32% protein content. Accordingly, pandas have evolved a higher capability to digest starches than strict carnivores.[50] Raw bamboo is toxic, containing cyanide compounds. Pandas' body tissues are less able than herbivores to detoxify cyanide, but their gut microbiomes are significantly enriched in putative genes coding for enzymes related to cyanide degradation, suggesting that they have cyanide-digesting gut microbes.[51] It has been estimated that an adult panda absorbs 54.8–66.1 mg (0.846–1.020 gr) of cyanide a day through its diet. To prevent poisoning, they have evolved anti-toxic mechanisms to protect themselves. About 80% of the cyanide is metabolized to less toxic thiocyanate and discharged in urine, while the remaining 20% is detoxified by other minor pathways.[52]