Slow loris: Difference between revisions

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Like other living ("[[Crown group|crown]]") strepsirrhines, these [[Nocturnality|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 [[Sensory system|sense organ]]. Because of their close relation to lemurs and other lorisiforms, they also possess a [[toothcomb]], which is used in [[Personal grooming|personal]], [[social grooming]], and 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 (anatomy)|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.
 
Like other living ("[[Crown group|crown]]") strepsirrhines, these [[Nocturnality|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 [[Sensory system|sense organ]]. Because of their close relation to lemurs and other lorisiforms, they also possess a [[toothcomb]], which is used in [[Personal grooming|personal]], [[social grooming]], and 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 (anatomy)|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. The [[toxin]] is produced by licking a [[gland]] on their arm, and the [[secretion]] mixes with its [[saliva]] to form the toxin. The toxin is also applied as a form of protection for their infants during grooming. They move slowly and deliberately, making little or no noise, and when threatened, they freeze and become docile. Little is known about their social structure, but they are known to communicate by [[Territory (animal)|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 [[omnivore]]s, eating small animals, fruit, [[Gum (botany)|tree gum]], and other vegetation.
+
Slow lorises and possibly some of their closest relatives have a toxic bite—a rare trait among mammals. The [[toxin]] is produced by licking a [[gland]] on their arm, and the [[secretion]] mixes with its [[saliva]] to form the toxin. The toxin is also applied as a form of protection for their infants during grooming. They move slowly and deliberately, making little or no noise, and when threatened, they freeze and become docile. Little is known about their social structure, but they are known to communicate by [[Territory (animal)|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 [[omnivore]]s, eating small animals, fruit, [[Gum (botany)|tree gum]], and other vegetation. Slow Lorises are treated with absoloute cruelty, being tickled into stupours, exposed to harmful UV rays and having their teeth pulled out. The Society for the Protection of Slow Lorises (SPOSL) try to prevent this.
   
 
All slow loris species are listed as either "[[Vulnerable species|Vulnerable]]" or "[[Endangered species|Endangered]]" on the [[IUCN Red List|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 [[Habitat fragmentation|fragmented]], making it nearly impossible for slow lorises to [[Biological dispersal|disperse]] between forest fragments, unsustainable demand from the [[exotic pet]] trade and [[traditional medicine]] has been the greatest cause for their decline. Despite local laws prohibiting the trade in slow lorises and slow loris products, as well as protection from international commercial trade under [[CITES#Appendix I|Appendix I]], slow lorises are openly sold in animal markets in Southeast Asia and smuggled to countries like Japan. They have also been popularized as pets in [[viral video]]s on [[YouTube]]. Slow lorises have their teeth cut or pulled out for the pet trade, and often die from infection, blood loss, poor handling, or poor nutrition.
 
All slow loris species are listed as either "[[Vulnerable species|Vulnerable]]" or "[[Endangered species|Endangered]]" on the [[IUCN Red List|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 [[Habitat fragmentation|fragmented]], making it nearly impossible for slow lorises to [[Biological dispersal|disperse]] between forest fragments, unsustainable demand from the [[exotic pet]] trade and [[traditional medicine]] has been the greatest cause for their decline. Despite local laws prohibiting the trade in slow lorises and slow loris products, as well as protection from international commercial trade under [[CITES#Appendix I|Appendix I]], slow lorises are openly sold in animal markets in Southeast Asia and smuggled to countries like Japan. They have also been popularized as pets in [[viral video]]s on [[YouTube]]. Slow lorises have their teeth cut or pulled out for the pet trade, and often die from infection, blood loss, poor handling, or poor nutrition.

Revision as of 13:20, 25 March 2011

Slow lorises[1]
Nycticebus coucang 002.jpg
Sunda slow loris
Nycticebus coucang
CITES Appendix I (CITES)[2]
Scientific classification
Kingdom: Animalia
Phylum: Chordata
Class: Mammalia
Order: Primates
Family: Lorisidae
Subfamily: Lorinae
Genus: Nycticebus
E. Geoffroy, 1812
Type species
Tardigradus coucang
Boddaert, 1785
Species

Nycticebus coucang
Nycticebus bengalensis
Nycticebus pygmaeus
Nycticebus javanicus
Nycticebus menagensis
Nycticebus linglom

Range map showing ranges of the three species of slow loris: the Sunda Loris (N. coucang) in Thailand, Malaysia, and Indonesia; the Bengal Slow Loris (N. bengalensis) in east India, China, Bangladesh, Bhutan, Burma, Thailand, Laos, Vietnam, and Cambodia; and the Pygmy Slow Loris (N. pygmaeus) in Vietnam and Laos.
Distribution of Nycticebus spp.
red = N. pygmaeus; blue = N. bengalensis;
brown = N. coucang, N. javanicus, & N. menagensis

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. They are also closely related to the remaining lorisiforms—the various types of galago—as well as the lemurs of Madagascar. Their evolutionary history is uncertain since their fossil record is patchy and molecular clock studies have given unclear or contradictory results.

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, social grooming, and 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. The toxin is produced by licking a gland on their arm, and the secretion mixes with its saliva to form the toxin. The toxin is also applied as a form of protection for their infants during grooming. They move slowly and deliberately, making little or no noise, and when threatened, they freeze and become docile. 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. Slow Lorises are treated with absoloute cruelty, being tickled into stupours, exposed to harmful UV rays and having their teeth pulled out. The Society for the Protection of Slow Lorises (SPOSL) try to prevent this.

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. Despite local laws prohibiting the 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 countries like Japan. They have also been popularized as pets in viral videos on YouTube. Slow lorises have their teeth cut or pulled out for the pet trade, and often die from infection, blood loss, poor handling, or poor nutrition.

Etymology

The genus Nycticebus was named in 1812 by Étienne Geoffroy Saint-Hilaire[1] for its nocturnal behavior. The name derives from the Ancient Greek nycti- (νύξ, genitive form νυκτός), meaning "night" and cebus (κῆβος) meaning "monkey".[3]

The word "loris" was first used in 1765 by the French naturalist Georges-Louis Leclerc, Comte de Buffon as a close equivalent to the Dutch name, loeris. This etymology was later supported by the physician William Baird in the 1820s, who noted that the Dutch word loeris signified "a clown."[4]

In Indonesia, slow lorises are called malu malu or "shy one" because they freeze and cover their face when spotted.[5] The Acehnese name, buah angin ("wind monkey"), refers to their ability to "fleetingly but silently escape".[6]

Evolutionary history

Slow lorises (genus Nycticebus) are strepsirrhine primates and are related to other living lorisiforms, such as slender lorises, pottos, false pottos, angwantibos, and galagos, as well as the lemurs of Madagascar.[7] The fossil record in both Asia and Africa is patchy, with most fossils dating back to the early Miocene, approximately 20 million years ago.[8] The evolutionary origins of living (crown) strepsirrhines have traditionally been unclear due to a lack of sufficient fossil evidence, and often contradictory molecular clock, morphological, and biogeographic studies.[7] In 2003 however, teeth and jaw fragments dating to the Late Middle Eocene (c. 40 million years ago) were found at the Birket Qarun Formation in the Egyptian Faiyum and were named Karanisia clarki. This fossil species is the oldest specimen to possess a toothcomb, a dental feature common among all living lorisiforms and lemurs, and has helped secure the evolutionary origins of the crown strepsirrhines in Africa.[9] One of the simplest models of lorisiform evolution suggests that they diverged first from the lemurs and then from each other in Africa, with one group of lorisids later migrating to Asia and evolving into the slender and slow lorises of today.[10] Slow lorises are thought to have reached the islands of Sundaland during times of low sea level, when the Sunda Shelf was exposed, creating a land bridge between the mainland and islands off the coast of Southeast Asia.[11] Molecular clock analysis suggests that slow lorises may have started evolving into distinct species about 6 million years ago.[12]

Although Karanisia has been cautiously placed with angwantibos (lorisoids from Africa, genus Arctocebus) several other fossil species have been discovered in Asia that are more closely related to the slow lorises.[13] The fossil genus Nycticeboides dates from the late Miocene, and was found in Pakistan. Although it was comparable in size to the pygmy slow loris (Nycticebus pygmaeus), its teeth set it apart from living slow lorises.[14] In 1997, French paleontologists reported the discovery of a single tooth from a Miocene site in Thailand.[15] The tooth most closely resembled living slow lorises, and based on this limited material, it was named Nycticebus linglom, using open nomenclature (the preceding "?") to indicate the tentative nature of the assignment.[16]

The living slow lorises are generally considered to be most closely related to the slender lorises (genus Loris) of India, followed by the angwantibos, pottos, (genus Perodicticus), and the false potto (genus Pseudopotto), all from Central and West Africa.[13] However, the relationship between the African lorises and the Asian lorises is complicated by biogeography, strong similarities in morphology (with both slender and robust body forms existing in both Africa and Asia), and significant differences in genetics.[7]

Taxonomy and phylogeny

... it had the face of a bear, the hands of a monkey, [and] moved like a sloth ...

American zoologist Dean Conant Worcester, describing the Bornean slow loris in 1891.[17]

One of the earliest mentions of a slow loris in the scientific literature was written by Carl Linnaeus in his 1753 Systema Naturae; Linnaeus placed Lemur tardigradus (later Nycticebus coucang) at the start of his list of lemur species.[18] In 1770, Dutchman Arnout Vosmaer (1720–1799) described a specimen of N. coucang he had received two years earlier to which he gave the French name "le paresseuz pentadactyle du Bengale" ("the five-fingered sloth of Bengal"). The Dutch physician and naturalist Pieter Boddaert later questioned Vosmaer's decision to affiliate the animal with sloths, arguing instead that it was more closely aligned with the lorises of Ceylon (now Sri Lanka) and Bengal.[19] In 1794, Boddaert was the first to officially describe a species of slow loris, under the name Tardigradus coucang. Several species were described in the following years: Nycticebus bengalensis (originally Loris bengalensis) by Bernard Germain de Lacépède in 1800; Nycticebus javanicus by Étienne Geoffroy Saint-Hilaire in 1812;[20] Nycticebus menagensis (originally Lemur menagensis) by Richard Lydekker in 1893;[21] and Nycticebus pygmaeus by John James Lewis Bonhote in 1907.[22] Geoffroy Saint-Hilaire defined the genus Nycticebus in 1812, setting Nycticebus coucang (then called Tardigradus coucang) as the type species.





N. menagensis






N. bengalensis, N. coucang



N. coucang




N. coucang*




N. javanicus





N. pygmaeus




Phylogeny and relationships of N. coucang and related species based on mitochondrial DNA sequences.[23]

In his influential 1952 book Primates: Comparative Anatomy and Taxonomy, the primatologist William Charles Osman Hill consolidated all the slow lorises in one species, N. coucang.[24] In 1971 Colin Groves recognized the pygmy slow loris (N. pygmaeus) as a separate species,[25] and divided N. coucang into four subspecies,[26] 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).[27] Species differentiation was based largely on differences in morphology, such as size, fur color, and head markings.[28]

To help clarify species and subspecies boundaries, and to establish whether morphology-based classifications were consistent with evolutionary relationships, the phylogenetic 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 karyotypes,[29] restriction enzymes,[30] and DNA sequences[31] were focused on understanding the relationships between species in the genus, not the phylogeny of the entire genus.[28] Although the sample size was limited, Chen and colleagues' 2006 publication showed that the lineages of Nycticebus can be generally divided into N. pygmaeus—which is deeply separated from the other slow lorises, and is thought to have been the first to diverge evolutionarily—and the other species. The analysis suggested that DNA sequences from some individuals of N. coucang and N. bengalensis apparently share a closer evolutionary relationship with each other than with members of their own species. The authors suggest that this result may be explained by introgressive hybridization, as the tested individuals of these two taxa originated from a region of sympatry in southern Thailand; the precise origin of one of the N. coucang individuals was not known.[28] 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 between the two species.[32]

Description

Skull of the Sunda slow loris

Slow lorises have a round head[33] because their skull is shorter from front to back compared to other prosimians.[34] Like other lorisids, its snout does not taper towards the front of the face as it does in lemurs, making the face appear less long and pointed.[35] Compared to the slender lorises, the snout of the slow loris is even less pointed.[33] The skull has prominent crests (ridges of bone).[36] A distinguishing feature of the slow loris skull is that the occipital bone is flattened and faces backward. The foramen magnum (hole through which the spinal cord enters) faces directly backward.[37] The brain of slow lorises has more folds (convolutions) than the brains of galagos.[38]

Coloration patterns around the eyes differ between the slender lorises (middle two) and the slow lorises (top and bottom).

The ears are reduced in size,[7] sparsely covered in hair, and hidden in the fur.[39] 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.[39] Like other strepsirrhine primates, the nose and lip are covered by a moist skin called the rhinarium ("wet nose"), which is a sense organ.[40]

The eyes of slow lorises are forward-facing, which gives good depth-perception. Their eyes are large[36][41] and possess a reflective layer, called the tapetum lucidum, that improves low-light vision. It is possible this layer may blur the images they see as the reflected light may interfere with the incoming light.[42] Slow lorises have monochromatic vision, meaning they see in shades of only one color. They lack the opsin gene that would allow them to detect short wavelength light, which includes the colors blue to green.[43]

The dental formula of slow lorises is 2.1.3.32.1.3.3 × 2 = 36, meaning that on each side of the mouth there is two upper and lower incisors, one upper and lower canine tooth, three upper and lower premolars, and three upper and lower molars, giving a total of 36 permanent teeth.[44][36] Like all other crown strepsirrhines, their lower incisors and canine are procumbent (lie down and face outwards), forming a toothcomb, which is used for personal, social grooming, and feeding.[44][45] They have relatively large canine teeth, their inner upper incisors are larger than the outer upper incisors, and they have a diastema (gap) between the canine and the first premolar. Their first premolar is elongated, and the last molar has three cusps on the crown of the tooth, the shortest of which is near the back. The palate (roof of the mouth) only goes as far back as the second molar.[36]

Slow lorises range in weight from the pygmy slow loris at 265 grams (9.3 oz) to as much as 2,100 grams (74 oz) for the Bengal slow loris.[46] Slow lorises have a stout body,[39] and their tail is greatly reduced and hidden beneath the dense fur.[7][39] Their combined head and body length varies by species, with the smallest, the pygmy slow loris, measuring 18 to 21 cm (7.1 to 8.3 in) to the Sunda slow loris measuring 27 to 38 cm (11 to 15 in).[39] Their trunk is longer than other prosimians[47] because they have 15–16 thoracic vertebrae compared to 12–14 in other prosimians.[48] This gives them greater mobility when twisting and extending towards nearby branches.[41] Their other vertebrae include seven cervical vertebrae, six or seven lumbar vertebrae, six or seven sacral vertebrae, and seven to eleven caudal vertebrae.[48]

The eyes of slow lorises are large and have a reflective layer, called the tapetum lucidum, to help them see better at night.

Compared to galagos, which have longer legs than arms, slow lorises have arms and legs of nearly equal length.[7] Their intermembral index (ratio of arm to leg length) averages 89, indicating their forelimbs are slightly shorter than their hindlimbs.[39] Like the slender lorises, their arms are slightly longer than their body,[48] however, the extremities of slow loris are more stout.[39]

Slow lorises have a powerful grasp with both their hands and feet due to several specializations.[39][49] They can tightly grasp branches with little effort because of a special muscular arrangement in their hands and feet, where their thumb is nearly perpendicular (~180°) to the rest of the fingers and the hallux (big toe) ranges between being perpendicular to pointing slightly backwards.[7][49][50] They have a large flexor muscle of the toes that originates on the lower end of the thigh bone, which helps impart a strong grasping ability to the hind limbs.[51] The second digit of the hand is short compared to the other digits,[39] while on the foot, the fourth toe is the longest.[48] Their sturdy thumb helps to act like a clamp when digits three, four, and five grasp the opposite side of a tree branch.[7][39] This gives their hands and feet a pincer-like appearance.[7] Their 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 members of the lorisine subfamily.[7][33][50] Both slender and slow lorises have relatively short feet.[48] Like nearly all crown strepsirrhines, they have a toilet-claw or grooming claw on the second toe of each foot.[7][48]

Slow lorises have an unusually low basal metabolic rate. This may be as little as 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 can be fatal to humans.[52]

Distribution and diversity

Slow lorises are found in South and Southeast Asia. Their collective range stretches from Northeast India through Indochina, east to the Sulu Archipelago (the small, southern islands of the Philippines), and south to the island of Java (including the Borneo, Sumatra, and many small nearby islands). They are found in India (Assam province), China (Yunnan province), Laos, Vietnam, Cambodia, Bangladesh, Burma, Thailand, Malaysia, the Philippines, and Indonesia. They have also been reported in Mindanao, the eastern-most island of the Philippines, although they were likely introduced there by humans.[53]

There are currently five recognized species. The pygmy slow loris (N. pygmaeus) occurs east of the Mekong River in eastern Cambodia, in the Yunnan province of southern China, Laos, and Vietnam.[54] The Bornean slow loris (N. menagensis) is found in Brunei, Indonesia, Malaysia and the small southern islands of the Philippines.[55] The Javan slow loris (N. javanicus) is only found on the island of Java in Indonesia.[56] The Sunda slow loris (N. coucang) occurs in Indonesia, Malaysia, the Isthmus of Kra in southern Thailand, and Singapore.[57] The Bengal slow loris (N. bengalensis) has the largest distribution of all the slow lorises[58] and can be found in Bangladesh, Cambodia, southern China, Northeast India, Laos, Myanmar, Thailand, and Vietnam.[59]

Slow lorises range across tropical and subtropical regions,[60] are found in primary and secondary rainforests, as well as bamboo groves, and mangrove forests.[49][61] They prefer forests with high, dense canopies,[39][60] although some species have also be found in disturbed habitats, such as chocolate plantations and mixed-crop home gardens.[61] 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 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 0.05 lorises per kilometer for N. pygmaeus.[62]

Behavior and ecology

A small 6-week-old baby clings to its mothers back as she climbs vertically through the branches
Babies cling to the mother's back.

Little is known about the social structure of slow lorises, but they generally spend most of the night foraging alone.[63][64] Slow lorises sleep during the day, usually alone but occasionally with other slow lorises.[63] There is significant overlap between the home ranges of adults, and males may have larger home ranges than females.[63][64] In the absence of direct studies of slow lorises, primatologist Simon Bearder speculated that slow loris social behavior is similar to the potto, another slow-moving nocturnal primate.[65] 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, by limiting vocal exchanges and alarm calls and by scent marking with urine being the dominant form of communication.[49][65] Adult males are highly territorial and are aggressive towards other males.[49][66] Vocalizations include an affiliative (friendly) call krik, and a louder call resembling a crow's caw.[67] 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.[49][66]

Slow lorises are slow and deliberate climbers, and often hold onto branches with three of their four extremities.[68] To move between trees, they carefully grip the terminal branches of the neighboring tree and pull themselves across the small gap.[7] They will also grip branches with only their hind feet, lift themselves upright, and quickly launch forward with their hands to catch prey.[68] Due to their slow movement, all lorises, including the slow lorises have specially adapted mechanism for defense against predation. Their slow, deliberate movement hardly disturbs the vegetation and is almost completely silent. Once disturbed, they immediately freeze and remain docile. If cornered, they may adopt a defensive posture by curling up and lunging at the predator.[69]

Slow lorises can produce a secretion on their brachial gland (a gland on their arm) which when mixed with their saliva creates volatile, noxious toxin that is stored in the mouth. Before stashing their offspring in a secure location, female slow lorises will lick their brachial gland, and then groom their young with their toothcomb, depositing the toxin on their fur. When threatened, slow lorises may also lick their brachial gland and bite their aggressors, delivering the toxin into the wound. Slow lorises are known to be reluctant to release their bite, which is likely to maximize the transfer of toxins. Animal dealers in Southeast Asia keep tanks of water nearby so that in case of a bite, they can submerge both their arm and the slow loris to make the animal let go.[70] The toxin is similar to the allergen in cat dander,[71] and in tests, an African palm civet (Nandinia binotata) averted a sample.[70] Loris bites cause a painful swelling, but the toxin is mild and not fatal. The single case of human death reported in the scientific literature was believed to have resulted from anaphylactic shock.[72] Although the trait is rare among mammals, slow lorises may not be the only primates with this type of defense—the closely related pottos and slender lorises may share the trait.[70]

Slow lorises have a special network of capillaries in their hands and feet that allow them to cling to branches for hours without losing sensation.

Studies suggest that slow lorises are polygynandrous.[73] Infants are either parked on branches while their parents find food or else are carried by one of the parents.[66] Due to their long gestations (about six months), small litter sizes, low birth weights, long weaning times (three to six months),[74] and long gaps between births, slow loris populations have one of the slowest growth rates among mammals of similar size.[75] 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. Further, a seven-year study of captively-bred pygmy slow lorises revealed a skewed sex distribution, with 1.68 males born for every 1 female.[32]

Breeding may be continuous throughout the year. In captive Sunda slow lorises, mating primarily occurs between June and mid-September, with the estrus cycle lasting 29 to 45 days and estrus lasting one to five days. Likewise, gestation lasts 185 to 197 days, and the young, which weigh between 30 and 60 grams (1.1 and 2.1 oz) at birth, wean at five to seven months. 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 around 12 to 14 months and will chase them out. In captivity, they can live 20 or more years.[49]

Diet

Slow lorises are omnivores, eating insects, arthropods, small birds and reptiles, eggs, fruits, gums, nectar and other vegetation.[64][76][77] 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.[64][76][78] A more detailed study of a different Sunda slow loris population in 2002 and 2003 showed very different dietary proportions. This study showed a diet 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).[76] The Sunda slow loris eats insects which other predators avoid due to their repugnant taste or smell.[64] Captive slow lorises eat a wide variety of foods including bananas and other fruits, rice, dog-food, raw horse meat, insects, lizards, freshly killed chicken, mice, young hamsters and milk formula that is made by mixing instant baby food with egg and honey. Captive slow loris diets may be supplemented with cod-liver oil and bone meal.[79]

Slow lorises can eat while hanging upside down from a branch with both hands.[64] They spend about 20% of their nightly activities feeding.[63] Preliminary results of studies on the pygmy slow loris indicates 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.[63][76] However, one 2002 analysis of pygmy slow loris feces indicated that it contained 98% insect remains and just 2% plant remains.[79] The pygmy slow loris returns to the same gum feeding sites often and leaves conspicuous gouges on tree trunks when inducing the flow of exudates.[63][76] Slow lorises have been reported gouging for exudates from heights ranging from 1 m (3 ft 3 in) to as much as 12 m (39 ft); the gouging process, whereby the loris repetitively bangs its toothcomb into the hard bark, may be noisy enough to be audible up to 10 m (33 ft) away. The marks remaining after gouging can be used by field workers to assess loris presence in an area.[80] Captive pygmy slow lorises also make characteristic gouge marks in wooden substrates.[79] It is not known how the sympatric pygmy and Bengal slow loris partition their feeding niches.[76] 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.[81] 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 complex carbohydrates; and a short duodenum.[82][83]

Cultural references

Beliefs about slow lorises and their use in traditional practices is deep-rooted and goes back at least 300 years, if not earlier based on oral traditions.[84] In the late 1800s and early 1900s, it was reported that the people from the interior of the island 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.[85] 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.[86]

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 that slow lorises have medicinal powers because they require more than one hit with a stick to die.[85] 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.[85][41] 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 and Koh Kong Provinces of Cambodia.[85]

In the folklore of northern Thailand, the slow loris is considered venomous. This belief may have originated from the painful anaphylactic reactions that susceptible individuals experience when bitten by the animal.[72]

Conservation

Slow lorises are popular in the exotic pet trade, which threatens wild populations.

The two greatest threats to slow lorises are deforestation and the wildlife trade.[87] Slow lorises have lost a significant amount of habitat,[88] with habitat fragmentation isolating small populations and obstructing biological dispersal.[56] However, despite the lost habitat, their decline is most closely associated with unsustainable trade, either as exotic pets or for traditional medicine.[88] All species are listed either as "Vulnerable" or "Endangered" by the International Union for Conservation of Nature (IUCN).[89] When all five species were considered a single species, imprecise population data and their regular occurrence in Southeast Asian animal markets inaccurately suggested that slow lorises were common, resulting in a previous IUCN Red List assessment of "Least Concern" as recently as 2000.[6][57][90] Since 2007, all slow loris species are protected from commercial international trade under Appendix I.[91] Furthermore, local trade is illegal because every nation in which they occur naturally has laws protecting them.[92]

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.[85][91] Additionally, 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.[93]

Populations of slow loris species, such as the Bengal and Sunda slow loris, 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. The population has grown to 74 animals between the time they were imported in the late 1980s and 2008, with most of them born at the San Diego Zoo.[87]

Wildlife trade

Prior to the 1960, the hunting of slow lorises was sustainable,[88] but due to growing demand, decreased supply, and the subsequent increased value of the marketed wildlife, slow lorises have been overexploited and are in decline.[90] With the use of modern technology, such as battery-powered search lights, slow lorises have become easier to hunt because of their eye shine.[75] Traditional medicine made from loris parts are thought to cure many diseases,[85] 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 et al. (2010) showed that these belief systems were so strong that the majority of respondents expressed reluctance to consider alternatives to loris-based medicines.[90]

Even the best breeding facilities have great difficulty breeding lorises, and those that do often have difficulty keeping them alive. It is so easy to get access to wild-caught lorises, it is highly doubtful that a seller who claims to have captive-bred ones is telling the truth.

Primatologist Anna Nekaris, in 2009 discussing the misleading information posted on YouTube.[89]

Slow lorises are sold locally at street markets, but are also sold internationally over the Internet and in pet stores.[94][95] They are especially popular or trendy in Japan, particularly among women.[94][96] The reasons for their popularity, according to the Japan Wildlife Conservation Society (JWCS), are that "they're easy to keep, they don't cry, they're small, and just very cute."[96] Because of their "cuteness", videos of pet slow lorises are some of the mostly frequently watched animal-related viral videos on YouTube.[41][89] In 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.[97] According to Nekaris, these videos are misunderstood by most people who watch them since most don't realize it is illegal 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.[89][97] Despite frequent advertisements by pet shops in Japan, the World Conservation Monitoring Centre (WCMC) reported only a few dozen slow lorises were imported in 2006, suggesting frequent smuggling.[60] Slow lorises are also smuggled to China, Taiwan, Europe, the United States, and Saudi Arabia for use as pets.[95][96] There is also extensive smuggling of trade of slow loris in Poland and Russia, according to Dr. Nekaris.[97]

A small, young slow loris is gripped by its limbs while its front teeth are cut with fingernail cutter
Slow lorises have their front teeth cut or pulled before being sold as pets, a practice that often results in infection and death.

Even within their countries of origin, slow lorises are very popular pets,[98] particularly in Indonesia.[99] 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.[100] Furthermore, few know about their strong odor or their potentially lethal bite.[101] According to 59 monthly surveys and interviews with local traders taken during late 2000s, nearly a thousand locally sourced slow lorises exchanged hands in the Medan bird market in North Sumatra.[98]

International trade usually results in a high mortality rate during transit, between 30% and 90%. Slow lorises also experience many health problems as a result of both local and international trade.[96] In order to give the impression that the primates are tame and appropriate pets for children,[102] to protect people from their potentially toxic bite,[92] or to deceive buyers into thinking the animal is a baby,[96] animal dealers either pull the front teeth with pliers or wire cutters or they cut them off with nail cutters.[41][98][100] This results in severe bleeding, which sometimes causes shock or death,[41] and frequently leads to dental infection, which is fatal in 90% of all cases.[100][102] Without their teeth, the animals are no longer able to fend for themselves in the wild, and must remain in captivity for life.[100][102] 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.[95] As many as 95% of the slow lorises rescued from the markets die of dental infection or improper care.[102]

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.[96] Slow lorises are also very stress-sensitive and do not do well in captivity. Infection, stress, pneumonia, and poor nutrition lead to high death rates among pet lorises.[100] Common health problems seen in pet slow lorises include undernourishment, tooth decay, diabetes, obesity, and kidney failure.[89] Pet owners also fail to provide proper care because they are usually sleeping when the nocturnal pet is awake.[89][102]

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