Slow lorises (genus Nycticebus) are strepsirrhine primates found in South and Southeast Asia. They range from Northeast India to the southern Philippines and from the Yunnan province in China in the north to the island of Java in the south. There are currently five species recognized: Sunda slow loris (N. coucang), Bengal slow loris (N. bengalensis), pygmy slow loris (N. pygmaeus), Javan slow loris (N. javanicus), and the Bornean slow loris (N. menagensis). Slow lorises are most closely related to other lorisids, such as slender lorises, pottos, the false potto, and angwantibos.
Like other living ("crown") strepsirrhines, these nocturnal primates have a reflective layer in their eye called the tapetum lucidum, which enhances their night vision. They also have a rhinarium or "wet nose", which is a touch-based sense organ. Because of their close relation to lemurs and other lorisiforms, they also possess a toothcomb, which is used in personal and social grooming, as well as feeding. Like nearly all prosimian ("pre-monkey") primates, they have a toilet-claw, which is also used in grooming. Slow lorises have a round head, narrow snout, large eyes, and distinctive coloration patterns. Their arms and legs are nearly equal in length, and their trunk is long, allowing them to twist and extend to nearby branches. The hands and feet of slow lorises have several adaptations that give them a pincer-like grip and enable them to grasp branches for long periods of time. Slow lorises and possibly some of their closest relatives have a toxic bite—a rare trait among mammals. Little is known about their social structure, but they are known to communicate by scent-marking. Males are highly territorial. Slow lorises reproduce slowly, and the infants are initially parked on branches or carried by either parent. They are omnivores, eating small animals, fruit, tree gum, and other vegetation.
All slow loris species are listed as either "Vulnerable" or "Endangered" on the International Union for Conservation of Nature and Natural Resources Red List of Threatened Species (IUCN Red List) and are threatened by the wildlife trade and habitat loss. Although their habitat is rapidly disappearing and becoming fragmented, making it nearly impossible for slow lorises to disperse between forest fragments, unsustainable demand from the exotic pet trade and traditional medicine has been the greatest cause for their decline.