Slow Loris
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Slow lorises are a group of several
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
of
nocturnal Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite. Nocturnal creatures generally have highly developed sens ...
strepsirrhine Strepsirrhini or Strepsirhini (; ) is a suborder of primates that includes the lemuriform primates, which consist of the lemurs of Madagascar, galagos ("bushbabies") and pottos from Africa, and the lorises from India and southeast Asia. Colle ...
primate Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians (monkeys and apes, the latter including huma ...
s that make up the
genus Genus ( plural genera ) is a taxonomic rank used in the biological classification of extant taxon, living and fossil organisms as well as Virus classification#ICTV classification, viruses. In the hierarchy of biological classification, genus com ...
''Nycticebus''. Found in
Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical United Nations geoscheme for Asia#South-eastern Asia, south-eastern region of Asia, consistin ...
and bordering areas, they range from
Bangladesh Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world, with a population exceeding 165 million people in an area of . Bangladesh is among the mos ...
and
Northeast India , native_name_lang = mni , settlement_type = , image_skyline = , image_alt = , image_caption = , motto = , image_map = Northeast india.png , ...
in the west to the Sulu Archipelago in the
Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...
in the east, and from
Yunnan Yunnan , () is a landlocked Provinces of China, province in Southwest China, the southwest of the People's Republic of China. The province spans approximately and has a population of 48.3 million (as of 2018). The capital of the province is ...
province in China in the north to the island of
Java Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's List ...
in the south. Although many previous classifications recognized as few as a single all-inclusive species, there are now at least eight that are considered valid: the
Sunda slow loris The Sunda slow loris (''Nycticebus coucang'') or greater slow loris is a strepsirrhine primate and a species of slow loris native to Indonesia, West Malaysia, southern Thailand and Singapore. It measures from head to tail and weighs between . ...
(''N. coucang''),
Bengal slow loris The Bengal slow loris (''Nycticebus bengalensis'') or northern slow loris is a strepsirrhine primate and a species of slow loris native to the Indian subcontinent and Indochina. Its geographic range is larger than that of any other slow loris s ...
(''N. bengalensis''),
Javan slow loris The Javan slow loris (''Nycticebus javanicus'') is a strepsirrhine primate and a species of slow loris native to the western and central portions of the island of Java, in Indonesia. Although originally described as a separate species, it was co ...
(''N. javanicus''),
Philippine slow loris The Philippine slow loris (''Nycticebus menagensis'') is a strepsirrhine primate and a species of slow loris that is native to the north and east coastal areas of the island of Borneo, as well as the Sulu Archipelago in the Philippines. The sp ...
(''N. menagensis''), Bangka slow loris (''N. bancanus''),
Bornean slow loris ''Nycticebus borneanus'', the Bornean slow loris, is a strepsirrhine primate and a species of slow loris that is native to central south Borneo in Indonesia. Formerly considered a subspecies or synonym of '' N. menagensis'', it was promot ...
(''N. borneanus''), Kayan River slow loris (''N. kayan'') and Sumatran slow loris (''N. hilleri''). A ninth species, the
pygmy slow loris The pygmy slow loris (''Xanthonycticebus pygmaeus'') is a species of slow loris found east of the Mekong River in Vietnam, Laos, eastern Cambodia, and China. It occurs in a variety of forest habitats, including tropical dry forests, semi-everg ...
(''X. pygmaeus''), was recently moved to the new genus ''
Xanthonycticebus The pygmy slow loris (''Xanthonycticebus pygmaeus'') is a species of slow loris found east of the Mekong River in Vietnam, Laos, eastern Cambodia, and China. It occurs in a variety of forest habitats, including tropical dry forests, semi-evergre ...
''. After the pygmy slow loris, the group's closest relatives are the
slender loris The slender lorises (''Loris'') are a genus of loris native to India and Sri Lanka. The genus comprises two species, the red slender loris found in Sri Lanka and the gray slender loris from Sri Lanka and India. Slender lorises spend most of their ...
es of southern India and Sri Lanka. Their next closest relatives are the African lorisids, the
potto The pottos are three species of strepsirrhine primate in the genus ''Perodicticus'' of the family Lorisidae. In some English-speaking parts of Africa, they are called "softly-softlys". Etymology The common name "potto" may be from Wolof (a t ...
s,
false potto The false potto (''Pseudopotto martini'') is a lorisoid primate of uncertain taxonomic status found in Africa. Anthropologist Jeffrey H. Schwartz named it in 1996 as the only species of the genus ''Pseudopotto'' on the basis of two specimens ...
s, and
angwantibo Angwantibos are two species of strepsirrhine primates classified in the genus ''Arctocebus'' of the family Lorisidae. They are also known as golden pottos because of their yellow or golden coloration. Angwantibos live in tropical Africa and thei ...
s. They are less closely related to the remaining lorisoids (the various types of
galago Galagos , also known as bush babies, or ''nagapies'' (meaning "night monkeys" in Afrikaans), are small nocturnal primates native to continental, sub-Sahara Africa, and make up the family Galagidae (also sometimes called Galagonidae). They ar ...
), and more distantly to the
lemur Lemurs ( ) (from Latin ''lemures'' – ghosts or spirits) are Strepsirrhini, wet-nosed primates of the Superfamily (biology), superfamily Lemuroidea (), divided into 8 Family (biology), families and consisting of 15 genera and around 100 exist ...
s of
Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...
. Their evolutionary history is uncertain since their
fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
record is patchy and
molecular clock The molecular clock is a figurative term for a technique that uses the mutation rate of biomolecules to deduce the time in prehistory when two or more life forms diverged. The biomolecular data used for such calculations are usually nucleoti ...
studies have given inconsistent results. Slow lorises have a round head, a narrow snout, large eyes, and a variety of distinctive coloration patterns that are species-dependent. Their arms and legs are nearly equal in length, and their
torso The torso or trunk is an anatomical term for the central part, or the core, of the body of many animals (including humans), from which the head, neck, limbs, tail and other appendages extend. The tetrapod torso — including that of a human ...
is long and flexible, 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 have a toxic bite, a trait rare among mammals and unique among the primates. The
toxin A toxin is a naturally occurring organic poison produced by metabolic activities of living cells or organisms. Toxins occur especially as a protein or conjugated protein. The term toxin was first used by organic chemist Ludwig Brieger (1849– ...
is obtained by licking a sweat
gland In animals, a gland is a group of cells in an animal's body that synthesizes substances (such as hormones) for release into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland). Structure De ...
on their arm, and the
secretion 440px Secretion is the movement of material from one point to another, such as a secreted chemical substance from a cell or gland. In contrast, excretion is the removal of certain substances or waste products from a cell or organism. The classical ...
is activated by mixing with
saliva Saliva (commonly referred to as spit) is an extracellular fluid produced and secreted by salivary glands in the mouth. In humans, saliva is around 99% water, plus electrolytes, mucus, white blood cells, epithelial cells (from which DNA can be ...
. Their toxic bite, once thought to be primarily a deterrent to predators, has been discovered to be primarily used in disputes within the species. The secretion from the arm contains a chemical related to cat allergen, but may be augmented by secondary toxins from the diet in wild individuals. Slow lorises move slowly and deliberately, making little or no noise, and when threatened, they stop moving and remain motionless. Their only documented predators—apart from humans—include snakes,
changeable hawk-eagle The changeable hawk-eagle ''(Nisaetus cirrhatus)'' or crested hawk-eagle is a large bird of prey species of the family Accipitridae. More informal or antiquated English common names include the marsh hawk-eagle or Indian crested hawk-eagle.Ferguso ...
s and
orangutan Orangutans are great apes native to the rainforests of Indonesia and Malaysia. They are now found only in parts of Borneo and Sumatra, but during the Pleistocene they ranged throughout Southeast Asia and South China. Classified in the genu ...
s, although cats,
viverrid Viverridae is a family of small to medium-sized, feliform mammals. The viverrids () comprise 33 species placed in 14 genera. This family was named and first described by John Edward Gray in 1821. Viverrids occur all over Africa, southern Europe, ...
s and
sun bear The sun bear (''Helarctos malayanus'') is a species in the family Ursidae (the only species in the genus ''Helarctos'') occurring in the tropical forests of Southeast Asia. It is the smallest bear, standing nearly at the shoulder and weighing ...
s are suspected. Little is known about their social structure, but they are known to communicate by
scent marking In ethology, territory is the sociographical area that an animal consistently defends against conspecific competition (or, occasionally, against animals of other species) using agonistic behaviors or (less commonly) real physical aggression. ...
. Males are highly territorial. Slow lorises reproduce slowly, and the infants are initially parked on branches or carried by either parent. They are
omnivore An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nutr ...
s, eating small animals, fruit, tree gum, and other vegetation. Each of the slow loris species that had been identified prior to 2012 is listed as either " Vulnerable" or "
Endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inva ...
" on the
IUCN Red List The International Union for Conservation of Nature (IUCN) Red List of Threatened Species, also known as the IUCN Red List or Red Data Book, founded in 1964, is the world's most comprehensive inventory of the global conservation status of biol ...
. The three newest species are yet to be evaluated, but they arise from (and further reduce the ranks of) what was thought to be a single "vulnerable" species. All four of these are expected to be listed with at least the same, if not a higher-risk, conservation status. All slow lorises are threatened by the
wildlife trade Wildlife trade refers to the of products that are derived from non-domesticated animals or plants usually extracted from their natural environment or raised under controlled conditions. It can involve the trade of living or dead individuals, ti ...
and
habitat loss Habitat destruction (also termed habitat loss and habitat reduction) is the process by which a natural habitat becomes incapable of supporting its native species. The organisms that previously inhabited the site are displaced or dead, thereby ...
. 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 An exotic pet is a pet which is relatively rare or unusual to keep, or is generally thought of as a wild species rather than as a domesticated pet. The definition varies by culture, location, and over time—as animals become firmly enough esta ...
trade and from
traditional medicine Traditional medicine (also known as indigenous medicine or folk medicine) comprises medical aspects of traditional knowledge that developed over generations within the folk beliefs of various societies, including indigenous peoples, before the ...
has been the greatest cause for their decline. Deep-rooted beliefs about the supernatural powers of slow lorises, such as their purported abilities to ward off evil spirits or to cure wounds, have popularized their use in traditional medicine. Despite local laws prohibiting trade in slow lorises and slow loris products, as well as protection from international commercial trade under Appendix I, slow lorises are openly sold in animal markets in Southeast Asia and smuggled to other countries, such as Japan. Due in part to the large eyes that are an adaptation to their nocturnal lifestyle, they have also been popularized as '
cute Cuteness is a subjective term describing a type of attractiveness commonly associated with youth and appearance, as well as a scientific concept and analytical model in ethology, first introduced by Konrad Lorenz. Lorenz proposed the concept ...
' pets in
viral video A viral video is a video that becomes popular through a viral process of Internet sharing, typically through video sharing websites such as YouTube as well as social media and email.Lu Jiang, Yajie Miao, Yi Yang, ZhenZhong Lan, Alexander Haupt ...
s on
YouTube YouTube is a global online video platform, online video sharing and social media, social media platform headquartered in San Bruno, California. It was launched on February 14, 2005, by Steve Chen, Chad Hurley, and Jawed Karim. It is owned by ...
. Slow lorises have their teeth cut or pulled out for the pet trade. They make poor pets as they are nocturnal, have specialized diets, are difficult to care for, and often die from infection, blood loss, improper caring and handling or inadequate nutrition.


Taxonomy and systematics

Although many previous classifications recognized as few as a single all-inclusive species, there are now at least eight that are considered valid: Other than the
pygmy slow loris The pygmy slow loris (''Xanthonycticebus pygmaeus'') is a species of slow loris found east of the Mekong River in Vietnam, Laos, eastern Cambodia, and China. It occurs in a variety of forest habitats, including tropical dry forests, semi-everg ...
in sister genus ''
Xanthonycticebus The pygmy slow loris (''Xanthonycticebus pygmaeus'') is a species of slow loris found east of the Mekong River in Vietnam, Laos, eastern Cambodia, and China. It occurs in a variety of forest habitats, including tropical dry forests, semi-evergre ...
'', the group's closest relatives are the
slender loris The slender lorises (''Loris'') are a genus of loris native to India and Sri Lanka. The genus comprises two species, the red slender loris found in Sri Lanka and the gray slender loris from Sri Lanka and India. Slender lorises spend most of their ...
es of southern India and Sri Lanka. Their next closest relatives are the African lorisids, the
potto The pottos are three species of strepsirrhine primate in the genus ''Perodicticus'' of the family Lorisidae. In some English-speaking parts of Africa, they are called "softly-softlys". Etymology The common name "potto" may be from Wolof (a t ...
s,
false potto The false potto (''Pseudopotto martini'') is a lorisoid primate of uncertain taxonomic status found in Africa. Anthropologist Jeffrey H. Schwartz named it in 1996 as the only species of the genus ''Pseudopotto'' on the basis of two specimens ...
s, and
angwantibo Angwantibos are two species of strepsirrhine primates classified in the genus ''Arctocebus'' of the family Lorisidae. They are also known as golden pottos because of their yellow or golden coloration. Angwantibos live in tropical Africa and thei ...
s. They are less closely related to the remaining lorisoids (the various types of
galago Galagos , also known as bush babies, or ''nagapies'' (meaning "night monkeys" in Afrikaans), are small nocturnal primates native to continental, sub-Sahara Africa, and make up the family Galagidae (also sometimes called Galagonidae). They ar ...
), and more distantly to the
lemur Lemurs ( ) (from Latin ''lemures'' – ghosts or spirits) are Strepsirrhini, wet-nosed primates of the Superfamily (biology), superfamily Lemuroidea (), divided into 8 Family (biology), families and consisting of 15 genera and around 100 exist ...
s of
Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...
. Their evolutionary history is uncertain since their
fossil A fossil (from Classical Latin , ) is any preserved remains, impression, or trace of any once-living thing from a past geological age. Examples include bones, shells, exoskeletons, stone imprints of animals or microbes, objects preserved ...
record is patchy and
molecular clock The molecular clock is a figurative term for a technique that uses the mutation rate of biomolecules to deduce the time in prehistory when two or more life forms diverged. The biomolecular data used for such calculations are usually nucleoti ...
studies have given inconsistent results.


Evolutionary history

Slow lorises (genus ''Nycticebus'') are
strepsirrhine Strepsirrhini or Strepsirhini (; ) is a suborder of primates that includes the lemuriform primates, which consist of the lemurs of Madagascar, galagos ("bushbabies") and pottos from Africa, and the lorises from India and southeast Asia. Colle ...
primate Primates are a diverse order of mammals. They are divided into the strepsirrhines, which include the lemurs, galagos, and lorisids, and the haplorhines, which include the tarsiers and the simians (monkeys and apes, the latter including huma ...
s and are related to other living lorisoids, such as the
pygmy slow loris The pygmy slow loris (''Xanthonycticebus pygmaeus'') is a species of slow loris found east of the Mekong River in Vietnam, Laos, eastern Cambodia, and China. It occurs in a variety of forest habitats, including tropical dry forests, semi-everg ...
(''Xanthonycticebus''),
slender loris The slender lorises (''Loris'') are a genus of loris native to India and Sri Lanka. The genus comprises two species, the red slender loris found in Sri Lanka and the gray slender loris from Sri Lanka and India. Slender lorises spend most of their ...
es (''Loris''),
potto The pottos are three species of strepsirrhine primate in the genus ''Perodicticus'' of the family Lorisidae. In some English-speaking parts of Africa, they are called "softly-softlys". Etymology The common name "potto" may be from Wolof (a t ...
s (''Perodicticus''),
false potto The false potto (''Pseudopotto martini'') is a lorisoid primate of uncertain taxonomic status found in Africa. Anthropologist Jeffrey H. Schwartz named it in 1996 as the only species of the genus ''Pseudopotto'' on the basis of two specimens ...
s (''Pseudopotto''),
angwantibo Angwantibos are two species of strepsirrhine primates classified in the genus ''Arctocebus'' of the family Lorisidae. They are also known as golden pottos because of their yellow or golden coloration. Angwantibos live in tropical Africa and thei ...
s (''Arctocebus''), and
galago Galagos , also known as bush babies, or ''nagapies'' (meaning "night monkeys" in Afrikaans), are small nocturnal primates native to continental, sub-Sahara Africa, and make up the family Galagidae (also sometimes called Galagonidae). They ar ...
s (family Galagidae), and to the
lemur Lemurs ( ) (from Latin ''lemures'' – ghosts or spirits) are Strepsirrhini, wet-nosed primates of the Superfamily (biology), superfamily Lemuroidea (), divided into 8 Family (biology), families and consisting of 15 genera and around 100 exist ...
s of
Madagascar Madagascar (; mg, Madagasikara, ), officially the Republic of Madagascar ( mg, Repoblikan'i Madagasikara, links=no, ; french: République de Madagascar), is an island country in the Indian Ocean, approximately off the coast of East Africa ...
. They are most closely related to the pygmy slow loris, followed by the slender lorises of
South Asia South Asia is the southern subregion of Asia, which is defined in both geographical and ethno-cultural terms. The region consists of the countries of Afghanistan, Bangladesh, Bhutan, India, Maldives, Nepal, Pakistan, and Sri Lanka.;;;;;;;; ...
, the angwantibos, pottos and false pottos of
Central Central is an adjective usually referring to being in the center of some place or (mathematical) object. Central may also refer to: Directions and generalised locations * Central Africa, a region in the centre of Africa continent, also known as ...
and
West Africa West Africa or Western Africa is the westernmost region of Africa. The United Nations defines Western Africa as the 16 countries of Benin, Burkina Faso, Cape Verde, The Gambia, Ghana, Guinea, Guinea-Bissau, Ivory Coast, Liberia, Mali, Maurit ...
. Lorisoids are thought to have evolved in Africa, where most living species occur; later, one group may have migrated to Asia and evolved into the slender and slow lorises of today. Lorises first appear in the Asian fossil record in the
Miocene The Miocene ( ) is the first geological epoch of the Neogene Period and extends from about (Ma). The Miocene was named by Scottish geologist Charles Lyell; the name comes from the Greek words (', "less") and (', "new") and means "less recen ...
, with records in
Thailand Thailand ( ), historically known as Siam () and officially the Kingdom of Thailand, is a country in Southeast Asia, located at the centre of the Indochinese Peninsula, spanning , with a population of almost 70 million. The country is bo ...
around 18 million years ago (mya) and in
Pakistan Pakistan ( ur, ), officially the Islamic Republic of Pakistan ( ur, , label=none), is a country in South Asia. It is the world's List of countries and dependencies by population, fifth-most populous country, with a population of almost 24 ...
16 mya. The Thai record is based on a single tooth that most closely resembles living slow lorises and that is tentatively classified as a species of ''Nycticebus''. The species is named ? ''Nycticebus linglom'', using
open nomenclature Open nomenclature is a vocabulary of partly informal terms and signs in which a taxonomist may express remarks about their own material. This is in contrast to synonymy lists, in which a taxonomist may express remarks on the work of others. Common ...
(the preceding "?" indicates the tentative nature of the assignment). Several lorises are found in the
Siwalik The Sivalik Hills, also known as the Shivalik Hills and Churia Hills, are a mountain range of the outer Himalayas that stretches over about from the Indus River eastwards close to the Brahmaputra River, spanning the northern parts of the Indi ...
deposits of Pakistan, dating to 16 to 8 mya, including '' Nycticeboides'' and '' Microloris''. Most are small, but an unnamed form dating to 15–16 mya is comparable in size to the largest living slow lorises. Molecular clock analysis suggests that slow lorises may have started evolving into distinct species about 10 mya. They are thought to have reached the islands of
Sundaland Sundaland (also called Sundaica or the Sundaic region) is a biogeographical region of South-eastern Asia corresponding to a larger landmass that was exposed throughout the last 2.6 million years during periods when sea levels were lower. It ...
when the
Sunda Shelf Geologically, the Sunda Shelf is a south-eastern extension of the continental shelf of Mainland Southeast Asia. Major landmasses on the shelf include the Bali, Borneo, Java, Madura, and Sumatra, as well as their surrounding smaller islands. ...
was exposed at times of low sea level, creating a
land bridge In biogeography, a land bridge is an isthmus or wider land connection between otherwise separate areas, over which animals and plants are able to cross and Colonisation (biology), colonize new lands. A land bridge can be created by marine regre ...
between the mainland and islands off the coast of Southeast Asia.


Discovery and taxonomy

The earliest known mention of a slow loris in scientific literature is from 1770, when Dutchman Arnout Vosmaer (1720–1799) described a specimen of what we know today as ''N. bengalensis'' that he had received two years earlier. The French naturalist
Georges-Louis Leclerc, Comte de Buffon Georges-Louis Leclerc, Comte de Buffon (; 7 September 1707 – 16 April 1788) was a French naturalist, mathematician, cosmologist, and encyclopédiste. His works influenced the next two generations of naturalists, including two prominent Fr ...
, later questioned Vosmaer's decision to affiliate the animal with sloths, arguing that it was more closely aligned with the lorises of
Ceylon Sri Lanka (, ; si, ශ්‍රී ලංකා, Śrī Laṅkā, translit-std=ISO (); ta, இலங்கை, Ilaṅkai, translit-std=ISO ()), formerly known as Ceylon and officially the Democratic Socialist Republic of Sri Lanka, is an ...
(now Sri Lanka) and Bengal. The word "loris" was first used in 1765 by Buffon as a close equivalent to a Dutch name, ''loeris''. This
etymology Etymology ()The New Oxford Dictionary of English (1998) – p. 633 "Etymology /ˌɛtɪˈmɒlədʒi/ the study of the class in words and the way their meanings have changed throughout time". is the study of the history of the Phonological chan ...
was later supported by the
physician A physician (American English), medical practitioner (Commonwealth English), medical doctor, or simply doctor, is a health professional who practices medicine, which is concerned with promoting, maintaining or restoring health through th ...
William Baird in the 1820s, who noted that the Dutch word ''loeris'' signified "a clown". In 1785, the Dutch physician and naturalist
Pieter Boddaert Pieter Boddaert (1730 – 6 May 1795) was a Dutch physician and natural history, naturalist. Early life, family and education Boddaert was the son of a Middelburg jurist and poet by the same name (1694–1760). The younger Pieter obtained his M.D ...
was the first to officially
describe Shneur Hasofer is a Hasidic musician known as DeScribe. Hasofer's musical style has been characterized as "Hasidic hip-hop," "Hasidic rap" and "Hasidic R&B". Background Hasofer was born to a Chabad Hasidic family in Melbourne, Australia. Hasof ...
a species of slow loris using the name ''Tardigradus coucang''. This species was based on the "tailless maucauco" described by
Thomas Pennant Thomas Pennant (14 June Old Style, OS 172616 December 1798) was a Welsh natural history, naturalist, traveller, writer and antiquarian. He was born and lived his whole life at his family estate, Downing Hall near Whitford, Flintshire, in Wales ...
in 1781, which is thought to have been based on a Sunda slow loris, and on Vosmaer's description of a Bengal slow loris. Consequently, there has been some disagreement over the identity of ''Tardigradus coucang''; currently the name is given to the Sunda slow loris. The next slow loris species to be described was ''Lori bengalensis'' (currently ''Nycticebus bengalensis''), named by
Bernard Germain de Lacépède Bernard-Germain-Étienne de La Ville-sur-Illon, comte de Lacépède or La Cépède (; 26 December 17566 October 1825) was a French naturalist and an active freemason. He is known for his contribution to the Comte de Buffon's great work, the ...
in 1800. In 1812,
Étienne Geoffroy Saint-Hilaire Étienne Geoffroy Saint-Hilaire (15 April 177219 June 1844) was a French naturalist who established the principle of "unity of composition". He was a colleague of Jean-Baptiste Lamarck and expanded and defended Lamarck's evolutionary theories. ...
named the genus ''Nycticebus'', naming it for its
nocturnal Nocturnality is an animal behavior characterized by being active during the night and sleeping during the day. The common adjective is "nocturnal", versus diurnal meaning the opposite. Nocturnal creatures generally have highly developed sens ...
behavior. The name derives from the grc, νυκτός, (nyktos),
genitive In grammar, the genitive case (abbreviated ) is the grammatical case that marks a word, usually a noun, as modifying another word, also usually a noun—thus indicating an attributive relationship of one noun to the other noun. A genitive can al ...
form of (, "night"), and (, "monkey"). Geoffroy also named ''Nycticebus javanicus'' in this work. Later 19th-century authors also called the slow lorises ''Nycticebus'', but most used the species name ''tardigradus'' (given by Linnaeus in 1758 in the 10th edition of ''Systema Naturæ'') for slow lorises, until mammalogists
Witmer Stone Witmer Stone (September 22, 1866 – May 24, 1939) was an American ornithologist, botanist, and mammalogist, and was considered one of the last of the “great naturalists.” Stone is remembered principally as an ornithologist. He was preside ...
and James A. G. Rehn clarified in 1902 that Linnaeus's name actually referred to a slender loris. Several more species were named around 1900, including ''Nycticebus menagensis'' (originally ''Lemur menagensis'') by
Richard Lydekker Richard Lydekker (; 25 July 1849 – 16 April 1915) was an English naturalist, geologist and writer of numerous books on natural history. Biography Richard Lydekker was born at Tavistock Square in London. His father was Gerard Wolfe Lydekker, ...
in 1893 and ''Nycticebus pygmaeus'' by John James Lewis Bonhote in 1907. However, in 1939
Reginald Innes Pocock Reginald Innes Pocock F.R.S. (4 March 1863 – 9 August 1947) was a British zoologist. Pocock was born in Clifton, Bristol, the fourth son of Rev. Nicholas Pocock and Edith Prichard. He began showing interest in natural history at St. Edward ...
consolidated all slow lorises into a single
species In biology, a species is the basic unit of classification and a taxonomic rank of an organism, as well as a unit of biodiversity. A species is often defined as the largest group of organisms in which any two individuals of the appropriate s ...
, ''N. coucang'', and in his influential 1953 book ''Primates: Comparative Anatomy and Taxonomy'', primatologist
William Charles Osman Hill Dr William Charles Osman Hill FRSE FZS FLS FRAI (13 July 1901 – 25 January 1975) was a British anatomist, primatologist, and a leading authority on primate anatomy during the 20th century. He is best known for his nearly completed eight-vol ...
also followed this course. In 1971
Colin Groves Colin Peter Groves (24 June 1942 – 30 November 2017) was a British-Australian biologist and anthropologist. Groves was Professor of Biological Anthropology at the Australian National University in Canberra, Australia. Education Born in Englan ...
recognized the
pygmy slow loris The pygmy slow loris (''Xanthonycticebus pygmaeus'') is a species of slow loris found east of the Mekong River in Vietnam, Laos, eastern Cambodia, and China. It occurs in a variety of forest habitats, including tropical dry forests, semi-everg ...
(''N. pygmaeus'') as a separate species, and divided ''N. coucang'' into four
subspecies In biological classification, subspecies is a rank below species, used for populations that live in different areas and vary in size, shape, or other physical characteristics (morphology), but that can successfully interbreed. Not all species ...
, while in 2001 Groves opined there were three species (''N. coucang'', ''N. pygmaeus'', and ''N. bengalensis''), and that ''N. coucang'' had three subspecies (''Nycticebus coucang coucang'', ''N. c. menagensis'', and ''N. c. javanicus''). In 2006, the Bornean slow loris was elevated to the species level (as ''Nycticebus menagensis'') based on molecular analysis of
DNA sequences A nucleic acid sequence is a succession of bases signified by a series of a set of five different letters that indicate the order of nucleotides forming alleles within a DNA (using GACT) or RNA (GACU) molecule. By convention, sequences are us ...
of the
D-loop In molecular biology, a displacement loop or D-loop is a DNA structure where the two strands of a double-stranded DNA molecule are separated for a stretch and held apart by a third strand of DNA. An R-loop is similar to a D-loop, but in this ca ...
and the cytochrome ''b'' gene. In 2008, Groves and Ibnu Maryanto confirmed the promotion of the fifth species, the Javan slow loris, to species status, a move that had been suggested in previous studies from 2000. They based their decision on an analysis of cranial
morphology Morphology, from the Greek and meaning "study of shape", may refer to: Disciplines * Morphology (archaeology), study of the shapes or forms of artifacts * Morphology (astronomy), study of the shape of astronomical objects such as nebulae, galaxies ...
and characteristics of
pelage Fur is a thick growth of hair that covers the skin of mammals. It consists of a combination of oily #Guard hair, guard hair on top and thick #Down hair, underfur beneath. The guard hair keeps moisture from reaching the skin; the underfur acts as ...
. Species differentiation was based largely on differences in morphology, such as size, fur color, and head markings. To help clarify species and subspecies boundaries, and to establish whether morphology-based classifications were consistent with evolutionary relationships, the
phylogenetic In biology, phylogenetics (; from Greek φυλή/ φῦλον [] "tribe, clan, race", and wikt:γενετικός, γενετικός [] "origin, source, birth") is the study of the evolutionary history and relationships among or within groups o ...
relationships within the genus ''Nycticebus'' were investigated by Chen and colleagues using DNA sequences derived from the mitochondrial markers D-loop and cytochrome ''b''. Previous molecular analyses using
karyotype A karyotype is the general appearance of the complete set of metaphase chromosomes in the cells of a species or in an individual organism, mainly including their sizes, numbers, and shapes. Karyotyping is the process by which a karyotype is disce ...
s,
restriction enzyme A restriction enzyme, restriction endonuclease, REase, ENase or'' restrictase '' is an enzyme that cleaves DNA into fragments at or near specific recognition sites within molecules known as restriction sites. Restriction enzymes are one class o ...
s, and DNA sequences were focused on understanding the relationships between a few species, not the phylogeny of the entire genus. The analyses published in 2006 by Chen and colleagues' proved inconclusive, although one test suggested that ''N. coucang'' and ''N. bengalensis'' apparently share a closer evolutionary relationship with each other than with members of their own species, possibly due to
introgressive hybridization Introgression, also known as introgressive hybridization, in genetics is the transfer of genetic material from one species into the gene pool of another by the repeated backcrossing of an interspecific hybrid with one of its parent species. Intr ...
since the tested individuals of these two taxa originated from a region of
sympatry In biology, two related species or populations are considered sympatric when they exist in the same geographic area and thus frequently encounter one another. An initially interbreeding population that splits into two or more distinct species sh ...
in southern Thailand. This hypothesis was corroborated by a 2007 study that compared the variations in mitochondrial DNA sequences between ''N. bengalensis'' and ''N. coucang'', and suggested that there has been
gene flow In population genetics, gene flow (also known as gene migration or geneflow and allele flow) is the transfer of genetic material from one population to another. If the rate of gene flow is high enough, then two populations will have equivalent a ...
between the two species. In 2012, two taxonomic synonyms (formerly recognized as subspecies) of ''N. menagensis''—'' N. bancanus'' and '' N. borneanus''—were elevated to species status, and a new species—'' N. kayan''—was also distinguished from the same. Rachel Munds, Anna Nekaris and Susan Ford based these taxonomic revisions on distinguishable facial markings. With that, the ''N. menagensis''
species complex In biology, a species complex is a group of closely related organisms that are so similar in appearance and other features that the boundaries between them are often unclear. The taxa in the complex may be able to hybridize readily with each oth ...
that had been collectively known as the Bornean slow loris became four species: the
Philippine slow loris The Philippine slow loris (''Nycticebus menagensis'') is a strepsirrhine primate and a species of slow loris that is native to the north and east coastal areas of the island of Borneo, as well as the Sulu Archipelago in the Philippines. The sp ...
(''N. menagensis''), the
Bornean slow loris ''Nycticebus borneanus'', the Bornean slow loris, is a strepsirrhine primate and a species of slow loris that is native to central south Borneo in Indonesia. Formerly considered a subspecies or synonym of '' N. menagensis'', it was promot ...
(''N. borneanus''), the Bangka slow loris (''N. bancanus''), and the Kayan River slow loris (''N. kayan''). Nekaris and Nijman (2022) combined morphological, behavioural, karyotypical and genetic data and suggested that the pygmy slow loris is best placed in its own genus, ''Xanthonycticebus.''


Anatomy and physiology

Slow lorises have a round head because their
skull The skull is a bone protective cavity for the brain. The skull is composed of four types of bone i.e., cranial bones, facial bones, ear ossicles and hyoid bone. However two parts are more prominent: the cranium and the mandible. In humans, the ...
is shorter than in other living strepsirrhine. Like other lorisids, their snout does not taper towards the front of the face as it does in lemurs, making the face appear less long and pointed. Compared with the slender lorises, the snout of the slow loris is even less pointed. As with other members of Lorisidae, its interorbital distance is shorter than in lemurs. The skull has prominent crests (ridges of bone). A distinguishing feature of the slow loris skull is that the
occipital bone The occipital bone () is a neurocranium, cranial dermal bone and the main bone of the occiput (back and lower part of the skull). It is trapezoidal in shape and curved on itself like a shallow dish. The occipital bone overlies the occipital lobe ...
is flattened and faces backward. The
foramen magnum The foramen magnum ( la, great hole) is a large, oval-shaped opening in the occipital bone of the skull. It is one of the several oval or circular openings (foramina) in the base of the skull. The spinal cord, an extension of the medulla oblon ...
(hole through which the spinal cord enters) faces directly backward. The brains of slow lorises have more folds (convolutions) than the brains of galagos. The ears are small, sparsely covered in hair, and hidden in the fur. Similar to the slender lorises, the fur around and directly above the eyes is dark. Unlike the slender lorises, however, the white stripe that separates the eye rings broadens both on the tip of the nose and on the forehead while also fading out on the forehead. Like other strepsirrhine primates, the nose and lip are covered by a moist skin called the
rhinarium The rhinarium (New Latin, "belonging to the nose"; plural: rhinaria) is the furless skin surface surrounding the external openings of the nostrils in many mammals. Commonly it is referred to as the tip of the ''snout'', and breeders of cats and ...
("wet nose"), which is a sense organ. The eyes of slow lorises are forward-facing, which gives
stereo vision Stereopsis () is the component of depth perception retrieved through binocular vision. Stereopsis is not the only contributor to depth perception, but it is a major one. Binocular vision happens because each eye receives a different image becaus ...
. Their eyes are large and possess a reflective layer, called the
tapetum lucidum The ''tapetum lucidum'' ( ; ; ) is a layer of tissue in the eye of many vertebrates and some other animals. Lying immediately behind the retina, it is a retroreflector. It reflects visible light back through the retina, increasing the light a ...
, that improves low-light vision. It is possible that this layer blurs the images they see, as the reflected light may interfere with the incoming light. Slow lorises have monochromatic vision, meaning they see in shades of only one color. They lack the
opsin Animal opsins are G-protein-coupled receptors and a group of proteins made light-sensitive via a chromophore, typically retinal. When bound to retinal, opsins become Retinylidene proteins, but are usually still called opsins regardless. Most pro ...
gene that would allow them to detect short wavelength light, which includes the colors blue and green. The
dental formula Dentition pertains to the development of teeth and their arrangement in the mouth. In particular, it is the characteristic arrangement, kind, and number of teeth in a given species at a given age. That is, the number, type, and morpho-physiolo ...
of slow lorises is , meaning that on each side of the mouth there are two upper (maxillary) and lower (mandibular)
incisor Incisors (from Latin ''incidere'', "to cut") are the front teeth present in most mammals. They are located in the premaxilla above and on the mandible below. Humans have a total of eight (two on each side, top and bottom). Opossums have 18, whe ...
s, one upper and lower
canine tooth In mammalian oral anatomy, the canine teeth, also called cuspids, dog teeth, or (in the context of the upper jaw) fangs, eye teeth, vampire teeth, or vampire fangs, are the relatively long, pointed teeth. They can appear more flattened however ...
, three upper and lower
premolar The premolars, also called premolar teeth, or bicuspids, are transitional teeth located between the canine and molar teeth. In humans, there are two premolars per quadrant in the permanent set of teeth, making eight premolars total in the mouth ...
s, and three upper and lower
molars The molars or molar teeth are large, flat teeth at the back of the mouth. They are more developed in mammals. They are used primarily to grind food during chewing. The name ''molar'' derives from Latin, ''molaris dens'', meaning "millstone to ...
, giving a total of 36 permanent teeth. As in all other
crown A crown is a traditional form of head adornment, or hat, worn by monarchs as a symbol of their power and dignity. A crown is often, by extension, a symbol of the monarch's government or items endorsed by it. The word itself is used, partic ...
strepsirrhines, their lower incisors and canine are procumbent (lie down and face outwards), forming a
toothcomb A toothcomb (also tooth comb or dental comb) is a dental structure found in some mammals, comprising a group of front teeth arranged in a manner that facilitates grooming, similar to a hair comb. The toothcomb occurs in lemuriform primates ( ...
, which is used for
personal Personal may refer to: Aspects of persons' respective individualities * Privacy * Personality * Personal, personal advertisement, variety of classified advertisement used to find romance or friendship Companies * Personal, Inc., a Washington, ...
and
social grooming Social grooming is a behavior in which social animals, including humans, clean or maintain one another's body or appearance. A related term, allogrooming, indicates social grooming between members of the same species. Grooming is a major soci ...
and feeding. The toothcomb is kept clean by the sublingua or "under-tongue", a specialized structure that acts like a toothbrush to remove hair and other debris. The sublingua extends below the tip of the tongue and is tipped with
keratin Keratin () is one of a family of structural fibrous proteins also known as ''scleroproteins''. Alpha-keratin (α-keratin) is a type of keratin found in vertebrates. It is the key structural material making up scales, hair, nails, feathers, ho ...
ized, serrated points that rake between the front teeth. Slow lorises have relatively large maxillary canine teeth, their inner (mesial) maxillary incisors are larger than the outer (distal) maxillary incisors, and they have a
diastema A diastema (plural diastemata, from Greek διάστημα, space) is a space or gap between two teeth. Many species of mammals have diastemata as a normal feature, most commonly between the incisors and molars. More colloquially, the condition ...
(gap) between the canine and the first premolar. The first mandibular premolar is elongated, and the last molar has three cusps on the
crown A crown is a traditional form of head adornment, or hat, worn by monarchs as a symbol of their power and dignity. A crown is often, by extension, a symbol of the monarch's government or items endorsed by it. The word itself is used, partic ...
, the shortest of which is near the back. The bony
palate The palate () is the roof of the mouth in humans and other mammals. It separates the oral cavity from the nasal cavity. A similar structure is found in crocodilians, but in most other tetrapods, the oral and nasal cavities are not truly sepa ...
(roof of the mouth) only goes as far back as the second molar. Slow lorises range in weight from the Bornean slow loris at to as much as for the Bengal slow loris. Slow lorises have stout bodies, and their tails are only stubs and hidden beneath the dense fur. Their combined head and body lengths vary by species, but range from between all species. The trunk is longer than in other living strepsirrhines because they have 15–16
thoracic vertebrae In vertebrates, thoracic vertebrae compose the middle segment of the vertebral column, between the cervical vertebrae and the lumbar vertebrae. In humans, there are twelve thoracic vertebra (anatomy), vertebrae and they are intermediate in size b ...
, compared to 12–14 in other living strepsirrhines. This gives them greater mobility when twisting and extending towards nearby branches. Their other
vertebrae The spinal column, a defining synapomorphy shared by nearly all vertebrates,Hagfish are believed to have secondarily lost their spinal column is a moderately flexible series of vertebrae (singular vertebra), each constituting a characteristic i ...
include seven
cervical vertebrae In tetrapods, cervical vertebrae (singular: vertebra) are the vertebrae of the neck, immediately below the skull. Truncal vertebrae (divided into thoracic and lumbar vertebrae in mammals) lie caudal (toward the tail) of cervical vertebrae. In ...
, six or seven
lumbar vertebrae The lumbar vertebrae are, in human anatomy, the five vertebrae between the rib cage and the pelvis. They are the largest segments of the vertebral column and are characterized by the absence of the foramen transversarium within the transverse p ...
, six or seven sacral vertebrae, and seven to eleven caudal vertebrae. Unlike galagos, which have longer legs than arms, slow lorises have arms and legs of nearly equal length. Their intermembral index (ratio of arm to leg length) averages 89, indicating that their forelimbs are slightly shorter than their hind limbs. As with the slender lorises, their arms are slightly longer than their body, but the extremities of slow lorises are more stout. Slow lorises have a powerful grasp with both their hands and feet due to several specializations. They can tightly grasp branches with little effort because of a special muscular arrangement in their hands and feet, where the thumb diverges at nearly 180° from the rest of the fingers, while the hallux (big toe) ranges between being perpendicular and pointing slightly backwards. The toes have a large flexor digitorum longus muscle, flexor muscle that originates on the lower end of the Femur, thigh bone, which helps to impart a strong grasping ability to the hind limbs. The second digit of the hand is short compared to the other digits, while on the foot, the fourth toe is the longest. The sturdy thumb helps to act like a clamp when digits three, four, and five grasp the opposite side of a tree branch. This gives their hands and feet a pincer-like appearance. The strong grip can be held for hours without losing sensation due to the presence of a rete mirabile (network of capillaries), a trait shared among all lorises. Both slender and slow lorises have relatively short feet. Like nearly all lemuriforms, they have a grooming claw on the second toe of each foot. Slow lorises have an unusually low basal metabolic rate, about 40% of the typical value for placental mammals of their size, comparable to that of sloths. Since they consume a relatively high-calorie diet that is available year-round, it has been proposed that this slow metabolism is due primarily to the need to eliminate toxic compounds from their food. For example, slow lorises can feed on ''Gluta'' bark, which may be fatal to humans.


Distribution and diversity

Slow lorises are found in South and
Southeast Asia Southeast Asia, also spelled South East Asia and South-East Asia, and also known as Southeastern Asia, South-eastern Asia or SEA, is the geographical United Nations geoscheme for Asia#South-eastern Asia, south-eastern region of Asia, consistin ...
. Their collective range stretches from
Northeast India , native_name_lang = mni , settlement_type = , image_skyline = , image_alt = , image_caption = , motto = , image_map = Northeast india.png , ...
through Indochina, east to the Sulu Archipelago (the small, southern islands of the
Philippines The Philippines (; fil, Pilipinas, links=no), officially the Republic of the Philippines ( fil, Republika ng Pilipinas, links=no), * bik, Republika kan Filipinas * ceb, Republika sa Pilipinas * cbk, República de Filipinas * hil, Republ ...
), and south to the island of
Java Java (; id, Jawa, ; jv, ꦗꦮ; su, ) is one of the Greater Sunda Islands in Indonesia. It is bordered by the Indian Ocean to the south and the Java Sea to the north. With a population of 151.6 million people, Java is the world's List ...
(including Borneo, Sumatra, and many small nearby islands). They are found in India (Northeastern states), China (
Yunnan Yunnan , () is a landlocked Provinces of China, province in Southwest China, the southwest of the People's Republic of China. The province spans approximately and has a population of 48.3 million (as of 2018). The capital of the province is ...
province), Laos, Vietnam, Cambodia,
Bangladesh Bangladesh (}, ), officially the People's Republic of Bangladesh, is a country in South Asia. It is the eighth-most populous country in the world, with a population exceeding 165 million people in an area of . Bangladesh is among the mos ...
, Burma, Thailand, Malaysia, the Philippines, Indonesia, Brunei, and Singapore. There are currently seven recognized species. The
Bornean slow loris ''Nycticebus borneanus'', the Bornean slow loris, is a strepsirrhine primate and a species of slow loris that is native to central south Borneo in Indonesia. Formerly considered a subspecies or synonym of '' N. menagensis'', it was promot ...
(''N. menagensis''), found on Borneo and nearby islands, including the Sulu Archipelago, and in 2012 was split into four distinct species (adding ''N. bancanus'', ''N. borneanus'', and ''N. kayan''). The
Javan slow loris The Javan slow loris (''Nycticebus javanicus'') is a strepsirrhine primate and a species of slow loris native to the western and central portions of the island of Java, in Indonesia. Although originally described as a separate species, it was co ...
(''N. javanicus'') is only found on the island of Java in Indonesia. The
Sunda slow loris The Sunda slow loris (''Nycticebus coucang'') or greater slow loris is a strepsirrhine primate and a species of slow loris native to Indonesia, West Malaysia, southern Thailand and Singapore. It measures from head to tail and weighs between . ...
(''N. coucang'') occurs on Sumatra and the Malay Peninsula, including Singapore and southern Thailand (the Isthmus of Kra). The
Bengal slow loris The Bengal slow loris (''Nycticebus bengalensis'') or northern slow loris is a strepsirrhine primate and a species of slow loris native to the Indian subcontinent and Indochina. Its geographic range is larger than that of any other slow loris s ...
(''N. bengalensis'') has the largest distribution of all the slow lorises and can be found in Bangladesh, Cambodia, southern China, Northeast India, Laos, Burma, Thailand, and Vietnam. Slow lorises range across Tropics, tropical and Subtropics, subtropical regions and are found in primary and secondary rainforests, as well as bamboo groves and mangrove forests. They prefer forests with high, dense Canopy (biology), canopies, although some species have also been found in Disturbance (ecology), disturbed habitats, such as Theobroma cacao, cacao plantations and mixed-crop home gardens. Due largely to their nocturnal behavior and the subsequent difficulties in accurately quantifying abundance, data about the population size or distribution patterns of slow lorises is limited. In general, encounter rates are low; a combined analysis of several field studies involving transect surveys conducted in South and Southeast Asia determined encounter rates ranging from as high as 0.74 lorises per kilometer for ''N. coucang'' to as low as 0.1 lorises per kilometer for ''N. bengalensis''.


Behavior and ecology

Little is known about the social structure of slow lorises, but they generally spend most of the night foraging alone. Individuals sleep during the day, usually alone but occasionally with other slow lorises. Home ranges of adults may significantly overlap, and those of males are generally larger than those of females. In the absence of direct studies of the genus, primatologist Simon Bearder speculated that slow loris social behavior is similar to that of the
potto The pottos are three species of strepsirrhine primate in the genus ''Perodicticus'' of the family Lorisidae. In some English-speaking parts of Africa, they are called "softly-softlys". Etymology The common name "potto" may be from Wolof (a t ...
, another nocturnal primate. Such a social system is distinguished by a lack of matriarchy and by factors that allow the slow loris to remain inconspicuous and minimize energy expenditure. Vocal exchanges and alarm calls are limited; urine marking, scent marking with urine is the dominant form of communication. Adult males are highly territorial and are aggressive towards other males. Animal communication, Vocalizations include an affiliative (friendly) call ''krik'', and a louder call resembling a crow's caw. When disturbed, slow lorises can also produce a low buzzing hiss or growl. To make contact with other individuals, they emit a single high-pitched rising tone, and females use a high whistle when in estrus. Slow lorises are slow and deliberate climbers, and often hold on to branches with three of their four limbs. To move between trees, they carefully grip the terminal branches of the neighboring tree and pull themselves across the small gap. They will also grip branches with only their hind feet, lift themselves upright, and quickly launch forward with their hands to catch prey. Due to their slow movement, all lorises, including the slow lorises, have a specially adapted mechanism for defense against predation. Their slow, deliberate movement hardly disturbs the vegetation and is almost completely silent. Once disturbed, they immediately stop moving and remain motionless. In Indonesia, slow lorises are called ''malu malu'' or "shy one" because they freeze and cover their face when spotted. If cornered, they may adopt a defensive posture by curling up and lunging at the predator. The Acehnese language, Acehnese name, ''buah angin'' ("wind monkey"), refers to their ability to "fleetingly but silently escape". Little is known about the predation of slow lorises. Documented predators include snakes, the
changeable hawk-eagle The changeable hawk-eagle ''(Nisaetus cirrhatus)'' or crested hawk-eagle is a large bird of prey species of the family Accipitridae. More informal or antiquated English common names include the marsh hawk-eagle or Indian crested hawk-eagle.Ferguso ...
(''Nisaetus cirrhatus''), and Sumatran orangutans (''Pongo abelii''). Other potential predators include cats,
sun bear The sun bear (''Helarctos malayanus'') is a species in the family Ursidae (the only species in the genus ''Helarctos'') occurring in the tropical forests of Southeast Asia. It is the smallest bear, standing nearly at the shoulder and weighing ...
s (''Helarctos malayanus''), binturongs (''Arctictis binturong''), and Asian palm civets. Slow lorises produce a
secretion 440px Secretion is the movement of material from one point to another, such as a secreted chemical substance from a cell or gland. In contrast, excretion is the removal of certain substances or waste products from a cell or organism. The classical ...
from their brachial
gland In animals, a gland is a group of cells in an animal's body that synthesizes substances (such as hormones) for release into the bloodstream (endocrine gland) or into cavities inside the body or its outer surface (exocrine gland). Structure De ...
(a scent gland on the upper arm near the axilla) that is licked and mixed with their saliva. In tests, three predators—binturongs, clouded leopards (''Neofelis nebulosa''), and sun bears—retreated or showed other signs of displeasure when presented with cotton swabs anointed with a mixture of the toxic secretion and the saliva, whereas the toxic secretion alone generated mild interest. Before stashing their offspring in a secure location, female slow lorises will lick their brachial glands, and then groom their young with their toothcomb, depositing the toxin on their fur. When threatened, slow lorises may also lick their brachial glands and bite their aggressors, delivering the toxin into the wounds. Slow lorises can be reluctant to release their bite, which is likely to maximize the transfer of toxins. This toxic bite is a rare trait among mammals and unique to lorisid primates. It may also be used for defense against other slow lorises and Parasitism, parasites. According to Nekaris, this adaptation—along with vocalizations, movement, and coloration patterns similar to those of Naja, true cobras—may have evolved through Müllerian mimicry to protect slow lorises when they need to move across the ground due to breaks in the canopy. The secretion from the brachial gland of captive slow lorises is similar to the allergen in cat dander, hence the secretions may merely elicit an allergic reaction, not toxicosis. Loris bites cause a painful swelling, and the single case of human death reported in the scientific literature was believed to have resulted from Anaphylaxis, anaphylactic shock. To protect itself, the Slow loris has also been observed to rub the venom on its fur to chemically-defend itself from predators. Studies suggest that slow lorises are polygynandry, polygynandrous. Infants are either parked on branches while their parents find food or else are carried by one of the parents. Due to their long gestations (about six months), small litter sizes, low birth weights, long weaning times (three to six months), and long gaps between births, slow loris populations have one of the slowest growth rates among mammals of similar size. Pygmy slow lorises are likely to give birth to twins—from 50% to 100% of births, depending on the study; in contrast, this phenomenon is rare (3% occurrence) in Bengal slow lorises. A seven-year study of captive-bred pygmy slow lorises showed a skewed sex distribution, with 1.68 males born for every 1 female. Breeding may be continuous throughout the year. Copulation often occurs while suspended with the hands and feet clinging to horizontal branches for support. In captive Sunda slow lorises, mating primarily occurs between June and mid-September, with the Estrous cycle, estrus cycle lasting 29 to 45 days and estrus lasting one to five days. Likewise, gestation lasts 185 to 197 days, and the young weigh between at birth. Females reach sexual maturity at 18 to 24 months, while males are capable of reproducing at 17 months. However, the fathers become hostile towards their male offspring after 12 to 14 months and will chase them away. In captivity, they can live 20 or more years.


Diet

Slow lorises are
omnivore An omnivore () is an animal that has the ability to eat and survive on both plant and animal matter. Obtaining energy and nutrients from plant and animal matter, omnivores digest carbohydrates, protein, fat, and fiber, and metabolize the nutr ...
s, eating insects and other arthropods, small birds and reptiles, eggs, fruits, gum (botany), gums, nectar and miscellaneous vegetation. A 1984 study of the Sunda slow loris indicated that its diet consists of 71% fruit and gums, and 29% insects and other animal prey. A more detailed study of another Sunda slow loris population in 2002 and 2003 showed different dietary proportions, consisting of 43.3% gum, 31.7% nectar, 22.5% fruit, and just 2.5% arthropods and other animal prey. The most common dietary item was nectar from flowers of the Bertram palm (''Eugeissona tristis''). The Sunda slow loris eats insects that other predators avoid due to their repugnant taste or smell. Preliminary results of studies on the pygmy slow loris indicate that its diet consists primarily of gums and nectar (especially nectar from ''Saraca dives'' flowers), and that animal prey makes up 30–40% of its diet. However, one 2002 analysis of pygmy slow loris feces indicated that it contained 98% insect remains and just 2% plant remains. The pygmy slow loris often returns to the same gum feeding sites and leaves conspicuous gouges on tree trunks when inducing the flow of exudates. Slow lorises have been reported gouging for exudates at heights ranging from to as much as ; the gouging process, whereby the loris repetitively bangs its toothcomb into the hard bark, may be loud enough to be heard up to away. The marks remaining after gouging can be used by field workers to assess loris presence in an area. Captive pygmy slow lorises also make characteristic gouge marks in wooden substrates, such as branches. It is not known how the sympatric pygmy and Bengal slow lorises partition their feeding niches. The plant gums, obtained typically from species in the family Fabaceae (peas), are high in carbohydrates and lipids, and can serve as a year-around source of food, or an emergency reserve when other preferred food items are scarce. Several anatomical adaptations present in slow lorises may enhance their ability to feed on exudates: a long narrow tongue to make it easier to reach gum stashed in cracks and crevices, a large cecum to help the animal digest polysaccharide, complex carbohydrates, and a short duodenum to help quickly pass potentially toxic exudates. Slow lorises can use both hands to eat while hanging upside down from a branch. They spend about 20% of their nightly activities feeding.


In culture

Beliefs about slow lorises and their use in traditional practices are deep-rooted and go back at least 300 years, if not earlier based on oral traditions. In the late 19th and early 20th centuries, it was reported that the people from the interior of Borneo believed that slow lorises were the gatekeepers for the heavens and that each person had a personal slow loris waiting for them in the afterlife. More often, however, slow lorises are used in traditional medicine or to ward off evil. The following passage from an early textbook about primates is indicative of the superstitions associated with slow lorises:
Many strange powers are attributed to this animal by the natives of the countries it inhabits; there is hardly an event in life to man, woman or child, or even domestic animals, that may not be influenced for better or worse by the Slow Loris, alive or dead, or by any separate part of it, and apparently one cannot usually tell at the time, that one is under supernatural power. Thus a Malay may commit a crime he did not premeditate, and then find that an enemy had buried a particular part of a Loris under his threshold, which had, unknown to him, compelled him to act to his own disadvantage. ... [a slow loris's] life is not a happy one, for it is continually seeing ghosts; that is why it hides its face in its hands.
In the Mondulkiri Province of Cambodia, hunters believe that lorises can heal their own broken bones immediately after falling from a branch so that they can climb back up the tree. They also believe that slow lorises have medicinal powers because they require more than one hit with a stick to die. In the province of North Sumatra, the slow loris is thought to bring good luck if it is buried under a house or a road. In the same province, slow loris body parts were used to place curses on enemies. In Java, it was thought that putting a piece of its skull in a water jug would make a husband more docile and submissive, just like a slow loris in the daytime. More recently, researchers have documented the belief that the consumption of loris meat was an aphrodisiac that improves "male power". The gall bladder of the Bengal slow loris has historically been used to make ink for tattoos by the village elders in Pursat Province, Pursat and Koh Kong Provinces of Cambodia. Loris wine is a traditional Cambodian medicine supposed to alleviate the pain of childbirth, made from a mixture of loris bodies and rice wine.


Conservation

The two greatest threats to slow lorises are deforestation and the
wildlife trade Wildlife trade refers to the of products that are derived from non-domesticated animals or plants usually extracted from their natural environment or raised under controlled conditions. It can involve the trade of living or dead individuals, ti ...
. Slow lorises have lost a significant amount of habitat, with habitat fragmentation isolating small populations and obstructing biological dispersal. However, despite the lost habitat, their decline is most closely associated with unsustainable trade, either as
exotic pet An exotic pet is a pet which is relatively rare or unusual to keep, or is generally thought of as a wild species rather than as a domesticated pet. The definition varies by culture, location, and over time—as animals become firmly enough esta ...
s or for
traditional medicine Traditional medicine (also known as indigenous medicine or folk medicine) comprises medical aspects of traditional knowledge that developed over generations within the folk beliefs of various societies, including indigenous peoples, before the ...
. Each of the slow loris species that had been identified prior to 2012 are currently listed as either " Vulnerable" or "
Endangered An endangered species is a species that is very likely to become extinct in the near future, either worldwide or in a particular political jurisdiction. Endangered species may be at risk due to factors such as habitat loss, poaching and inva ...
" by the International Union for Conservation of Nature (IUCN) on their IUCN Red List, Red List. When they were all considered a single species, imprecise population data together with their regular occurrence in Southeast Asian animal markets combined to incorrectly suggest that slow lorises were common. This manifested as incorrect Red List assessments of "Least Concern" as recently as 2000. The three newest species are yet to be evaluated by the IUCN, although each was once thought to be subpopulations of the Bornean slow loris—which was evaluated as "Vulnerable" in 2008. With this division of its range and population, the Bornean slow loris and the three new species face a higher risk of extinction than before. Since 2007, all slow loris species have been protected from commercial international trade under Appendix I of CITES. Furthermore, local trade is illegal because every nation in which they occur naturally has laws protecting them. Despite their CITES Appendix I status and local legal protection, slow lorises are still threatened by both local and international trade due to problems with enforcement. Surveys are needed to determine existing population densities and habitat viability for all species of slow loris. Connectivity between protected areas is important for slow lorises because they are not adapted to dispersing across the ground over large distances. Populations of Bengal and Sunda slow lorises are not faring well in zoos. Of the 29 captive specimens in North American zoos in 2008, several are hybrids that cannot breed, while most are past their reproductive years. The last captive birth for these species in North America was in 2001 in San Diego. Pygmy slow lorises are doing better in North American zoos; from the late 1980s (when they were imported) to 2008, the population grew to 74 animals, with most of them born at the San Diego Zoo.


Wildlife trade

Until the 1960s, the hunting of slow lorises was sustainable, but due to growing demand, decreased supply, and the subsequent increased value of the marketed wildlife, slow lorises have been Overexploitation, overexploited and are in decline. With the use of modern technology, such as battery-powered searchlights, slow lorises have become easier to hunt because of their eyeshine. Traditional medicine made from loris parts is thought to cure many diseases, and the demand for this medicine from wealthy urban areas has replaced the subsistence hunting traditionally performed in poor rural areas. A survey by primatologist Anna Nekaris and colleagues (2010) showed that these belief systems were so strong that the majority of respondents expressed reluctance to consider alternatives to loris-based medicines. Slow lorises are sold locally at street markets but are also sold internationally over the Internet and in pet stores. They are especially popular or trendy in Japan, particularly among women. The reasons for their popularity, according to the Japan Wildlife Conservation Society, are that "they're easy to keep, they don't cry, they're small, and just very cute."


Common misconceptions

Because of their "cuteness", videos of pet slow lorises are some of the most frequently watched animal-related
viral video A viral video is a video that becomes popular through a viral process of Internet sharing, typically through video sharing websites such as YouTube as well as social media and email.Lu Jiang, Yajie Miao, Yi Yang, ZhenZhong Lan, Alexander Haupt ...
s on
YouTube YouTube is a global online video platform, online video sharing and social media, social media platform headquartered in San Bruno, California. It was launched on February 14, 2005, by Steve Chen, Chad Hurley, and Jawed Karim. It is owned by ...
. By March 2011, a newly posted video of a slow loris holding a cocktail umbrella had been viewed more than two million times, while an older video of a slow loris being tickled had been viewed more than six million times. According to Nekaris, these videos are misunderstood by most people who watch them, since most do not realize that it is illegal in most countries to own them as pets and that the slow lorises in the videos are only docile because that is their passive defensive reaction to threatening situations. Despite frequent advertisements by pet shops in Japan, the World Conservation Monitoring Centre reported that only a few dozen slow lorises were legally imported in 2006, suggesting frequent wildlife smuggling, smuggling. Slow lorises are also smuggled to China, Taiwan, Europe, Russia, the United States, and Saudi Arabia for use as pets. Within their countries of origin, slow lorises are very popular pets, particularly in Indonesia. They are seen as a "living toy" for children by local people or are bought out of pity by Western tourists or expatriates. Neither local nor foreign buyers usually know anything about these primates, their endangered status, or that the trade is illegal. According to ''National Geographic'', slow lorises are protected by both local laws in southern Asia and by the Convention on International Trade in Endangered Species (CITES). Furthermore, few know about their strong odor or their painful bite, which may lead to anaphylaxis in some cases. According to data compiled from monthly surveys and interviews with local traders, nearly a thousand locally-sourced slow lorises exchanged hands in the Medan bird market in North Sumatra during the late first decade of the 21st century. International trade usually involves a high mortality rate during transit, between 30% and 90%. Slow lorises also experience many health problems due to both local and international trade. In order to give the impression that the primates are tame and appropriate pets for children, to protect people from their potentially toxic bite, or to deceive buyers into thinking the animal is a baby, animal dealers either pull the front teeth with pliers or wire cutters or cut them off with nail clippers. This results in severe bleeding, which sometimes causes Shock (circulatory), shock or death. Dental infection is common and is fatal in 90% of cases. Without their teeth, the animals can no longer fend for themselves in the wild and must remain in captivity for life. The slow lorises found in animal markets are usually underweight and malnourished and have had their fur dyed, which complicates species identification at rescue centers. As many as 95% of the slow lorises rescued from the markets die of dental infection or improper care. As part of the trade, infants are pulled prematurely from their parents, leaving them unable to remove their own urine, feces, and oily skin secretions from their fur. Slow lorises have a special network of blood vessels in their hands and feet, which makes them vulnerable to cuts when pulled from the wire cages they are kept in. Slow lorises are also stress-sensitive and do not thrive in captivity. Common health problems seen in pet slow lorises include undernourishment, tooth decay, diabetes, obesity, and kidney failure. Infection, stress, pneumonia, and poor nutrition lead to high death rates among pet lorises. Pet owners also fail to provide proper care because they are usually asleep when the nocturnal pet is awake.


References


Works cited

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Abstract in French and English
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External links




International Animal Rescue: Saving the slow loris

Dr. Anna Nekaris' research and conservation

Primate Fact Sheets: Slow loris (''Nycticebus'')

Slow loris skeleton

Asian loris and African pottos conservation website directory
{{DEFAULTSORT:loris, slow Slow lorises, * Primates of Southeast Asia Venomous mammals Species endangered by the pet trade Taxa named by Étienne Geoffroy Saint-Hilaire, slow loris Taxa described in 1812