Melursus ursinus

The sloth bear (Melursus ursinus) is a myrmecophagous bear species native to the Indian subcontinent. It feeds on fruits, ants and termites. It is listed as Vulnerable on the IUCN Red List, mainly because of habitat loss and degradation. It has also been called 'labiated bear' because of its long lower lip and palate used for sucking insects. It has a long, shaggy fur, a mane around the face, and long, sickle-shaped claws. It is lankier than brown and Asian black bears.It shares features of insectivorous mammals and evolved during the Pleistocene from the ancestral brown bear through convergent evolution. Sloth bears breed during spring and early summer and give birth near the beginning of winter. When their territories are encroached upon by humans, they sometimes attack them. Historically, humans have drastically reduced their habitat and diminished their population by hunting them for food and products such as their bacula and claws. Sloth bears have been tamed and used as performing pets. Shaw in 1791 named the species Bradypus ursinus. In 1793, Meyer named it Melursus lybius, and in 1817, de Blainville named it Ursus labiatus because of its long lips. Illiger named it Prochilus hirsutus, the Greek genus name indicating long lips, while the specific name noted its long and coarse hair. Fischer called it Chondrorhynchus hirsutus, while Tiedemann named it Ursus longirostris. Sloth bears may have reached their current form in the Early Pleistocene, the time when the bear family specialized and dispersed. A fragment of fossilized humerus from the Pleistocene, found in Andhra Pradesh's Kurnool Basin is identical to the humerus of a modern sloth bear. The fossilized skulls of a bear once named Melursus theobaldi found in the Shivaliks from the Early Pleistocene or Early Pliocene are thought by certain authors to represent an intermediate stage between sloth bears and ancestral brown bears. M. theobaldi itself had teeth intermediate in size between sloth bears and other bear species, though its palate was the same size as the former species, leading to the theory that it is the sloth bear's direct ancestor. Sloth bears probably arose during the Middle Pliocene and evolved in the Indian subcontinent. The sloth bear shows evidence of having undergone a convergent evolution similar to that of other ant-eating mammals. Sloth bears adults are a medium-sized species though weight can range variously from 55 to 105 kg (121 to 231 lb) in typically-sized females and from 80 to 145 kg (176 to 320 lb) in typically-sized males. Exceptionally large specimens of females can scale up to 124 kg (273 lb) and males up to 192 kg (423 lb). The average weight of sloth bears from the nominate subspecies in Nepal was 95 kg (209 lb) in females and 114 kg (251 lb) in males. Nominate bears in India were found to weigh average 93.2 kg (205 lb) in males and 83.3 kg (184 lb) per one study. Specimens from Sri Lanka (M. u. inornatus) may weight up to 68.2 kg (150 lb) in females and 104.5 kg (230 lb) in males. However six Sri Lankan male sloth bears averaged only 74.8 kg (165 lb) and 57.5 kg (127 lb) was the average for four females, so Sri Lankan bears could be up to at least 30% lighter in body mass than nominate race bears and with apparent far more pronounced size sexual dimorphism. They are 60–92 cm (2 ft 0 in–3 ft 0 in) high at the shoulder, and have a body length of 1.4–1.9 m (4 ft 7 in–6 ft 3 in). Besides being smaller than males, females reportedly typically have more fur between their shoulders. Sloth bear muzzles are thick and long, with small jaws and bulbous snouts with wide nostrils. They have long lower lips which can be stretched over the outer edge of their noses, and lack upper incisors, thus allowing them to suck up large numbers of insects. The premolars and molars are smaller than in other bears, as they do not chew as much vegetation. In adults, the teeth are usually in poor condition, due to the amount of soil they suck up and chew when feeding on insects. The back of the palate is long and broad, as is typical in other ant-eating mammals. The paws are disproportionately large, and have highly developed, sickle-shaped, blunt claws which measure 10 cm (4 in) in length. Their toe pads are connected by a hairless web. They have the longest tail in the bear family, which can grow to 15–18 cm (6–7 in). Their back legs are not very strong, though they are knee-jointed, and allow them to assume almost any position. The ears are very large and floppy. The sloth bear is the only bear with long hair on its ears. Sloth bear fur is completely black (rusty for some specimens), save for a whitish Y- or V-shaped mark on the chest. This feature is sometimes absent, particularly in Sri Lankan specimens. This feature, which is also present in Asian black bears and sun bears, is thought to serve as a threat display, as all three species are sympatric with tigers (tigers usually do not carry out attacks on an adult bear if the bear is aware or facing the cat). The coat is long, shaggy, and unkempt, despite the relatively warm environment in which the species is found, and is particularly heavy behind the neck and between the shoulders, forming a mane which can be 30 cm (12 in) long. The belly and underlegs can be almost bare. Sloth bears are usually about the same size as an Asian black bear but are immediately distinctive for their shaggier coat, whitish claws, as well as their typically rangier build. Their head and mouth is highly distinct from that of a black bear with a longer, narrower skull shape (particularly the snout), loose-looking, flappier lips and paler muzzle colour. In few areas of overlap, sloth bear confusion with sun bears is unlikely, given the latter species considerably smaller size, much shorter fur, wrinkled folding skin (especially around the back), bolder chest marking and drastically different, more compact head structure and appearance.