Nycticebus coucang (Boddaert, 1785)
by Ms. Noor Faradiana Binti Md Fauzi, Mr. Mohammad Shahfiz Azman, Dr. Ahmad Khaldun Ismail & Dr Scott A Weinstein
© Rosnizam, R.

Nycticebus coucang commonly known as Sunda Slow Loris or Greater Slow Loris. It is also referred by local as Kera Duku or Kongkang. It is a mammal that constitutes Family Lorisidae and belongs to Order Primates (Francis, 2019). This species has been recorded in Indonesia (Sumatra); Malaysia (Peninsular Malaysia); Singapore and Thailand (Nekaris et al., 2020; Roos et al., 2014). The subspecies, Nycticebus coucang insularis, has been rediscovered at Tioman Island (Rovie-Ryan et al., 2018). In addition, Malaysian Sunda Slow Loris has also been characterized genetically at subspecies and species level to portray systematic relationships toward its sister taxon (Rovie-Ryan et al., 2019; Md-Zain et al., 2019).

The Sunda Slow Loris can be recognized by having grey-brown to reddish-brown pelage with a broad, darker-coloured stripe running down their back to the top of the head, which branches into four lines connecting to the eyes ears (Francis, 2019). It also possesses large eyes with a dark-coloured ring around each eye. The large eyes provide increased visual acuity to this mainly nocturnal primate. Moreover, it also has only stubs and hidden beneath the slow loris dense fur. Like other primates, it also has hand and feet that can grasp, digits with nails and both eyes on the front of the face (Francis, 2019). The range of head to body length of the Sunda Slow Loris is around 26-30 cm and can attain weights ranging from 375 grams to 900 grams (Francis, 2019).

The Sunda Slow Loris is mostly solitary; social contact is rare and these animals are arboreal, mostly inhabiting small to medium-sized trees in secondary forests. It also has been found in gardens as well as plantations. Wirdateti et al. (2005) reported that N. coucang prefers trees such as ficus and bamboo with tight arrangement of intertwining branches and vines that may provide some protection from predators and facilitates climbing. Furthermore, the roaming area of home ranges varies, probably due to habitat differences; adults inhabit overlapping ranges of 0.004 to 0.25 km2 (Wiens, 2002).

Nycticebus coucang consumes a wide variety of foods such as fruits, leaves, flower, nectars, gum, saps, stems, and occasionally insects (Wirdateti et al., 2005; Wiens et al., 2006). The remainder of its diet consists of assorted items, such as snails and bird eggs (Francis, 2019; Weins et al., 2006). The common name “slow loris” probably was applied because of it’s unhurried movement and the absence of leaping or jumping, as is commonly seen in other primates (Ishida et al., 1992). Although its has a high-energy diet , the Sunda Slow Loris has a slow metabolism. The low metabolism may be partly related to energy costs of detoxifying certain secondary plant compounds in many genera of plants that are consumed (Wiens et al., 2006).

The Sunda Slow Loris also has been termed a “unique primate”, as some authors have declared it “venomous” (Nekaris et al., 2013). It produces an oily secretion from brachial glands on the insides of its elbows (Phillipps & Phillips, 2016). This secretion has been hypothetically considered to have variously: a defensive function; a means to remove ectoparasites, and/or have a role in conspecific territoriality, and other proposed functions (e.g., see Hagey et al., 2007; Barrett et al., 2021; Nekaris et al., 2020; Grow et al., 2015). Several postures have been associated with the proposed use of this secretion including upper extremity elevation, and anointing the brachial gland secretion with saliva; ‘anointing’ behaviour can include application on the head, or oral retention of the secretion.

In addition, the Sunda Slow Loris also may apply or anoint this secretion while grooming by using a unique structure in it’s lower jaw called a ‘tooth comb’. As a slow loris is grooming, the branchial gland secretion can reportedly be transferred to offspring as well (Alterman, 1991; Nekaris et al., 2013). Some authors have asserted that the Sunda Slow Loris secretion functions as a “venom”; however, other authors have questioned whether there is sufficient evidence to support “venom function” in this species (e.g., Weinstein et al., 2013) especially because of the lack of evidence supporting a defensive role of this secretion (e.g., several predators including orang-utans and pythons actively prey on N. coucang, e.g., Utami & van Hooff, 1997). The secretion reportedly only becomes toxic once mixed with the saliva (Alterman, 1991). This primate is typically non-aggressive and only bite when they feel very threatened. Humans bitten by Nycticebus most commonly experience local effects including pain; however, the secretion contains a protein with notable similarity to a domestic cat allergen, Fel d-1 (this is the major allergen in cats), and some bitten persons develop life-threatening anaphylaxis (e.g., Wilde, 1972; Utap & Mohd Jamal, 2019; Inoue et al., 2021). This also may occur in susceptible persons after bites from a wide variety of animals and is not consistent with “envenoming” (Weinstein et al., 2013). Slow loris bites can cause moderately local pain in humans (Krane et al., 2003; Matthew et al., 2018), which may heal slowly. There were approximately 10 cases of N. coucang bites in human consulted to the Remote Evenomation Consultancy Services (RECS) in Malaysia from 2013 to 2021. These bite incidences were recorded in Johor, Melaka, Negri Sembilan, Sarawak and Sabah. All involved accidental bites from handling with unprotected hands causing moderate to severe pain. The ‘allergic’ reaction symptoms appears within a few minutes after the bite such as swelling of eyes and face, hoarseness of voice, shortness of breath and urticarial rash. Patients may present with signs of anaphylactic shock at the emergency department. These signs and symptoms reasolved following the standard treatment for acute anaphylaxis i.e. intravenous fluids, adrenaline, antihistamines and steroids. No death has been recorded from the bite of N. couchang in Malaysia.

According to the IUCN Red List of Threatened Species, this primate is categorized as Endangered and totally protected under the Wildlife Conservation Act 2010. In addition to the increasingly recognised impact of the pet trade, slow loris populations are also declining (probably more significantly) because of escalating habitat destruction as forests are destroyed for farms, roads and human settlements (Nekaris et al., 2020). The fragmentation of the forests cause broken habitat continuity that may restrict species dispersal because of the species reliance on continuous canopy cover in order to move from tree to tree. Therefore, appropriate conservation measures such as an awareness campaign to expand awareness of the importance of Sunda Slow Loris conservation and sustainable forest management is essential to help recovery of this endangered and less known mammal. It is also advisable not to keep Sunda Slow Loris as pets or to handle them with bare hands. It is important to seek urgent medical help if bitten.


  1. Alterman, L. (1991). Toxins and toothcombs: potential allospecific chemical defense in Nycticebus and Perodicticus. In Alterman, L., Doyle, G. & Izard, M.K. (Eds.), Creatures of the Dark. Springer, Boston, MA. pp. 413-424.
  2. Francis, C.M. (2019). A field guide to the mammals of South-East Asia. Bloomsbury Publishing Plc., London, United Kingdom.
  3. Grow, N.B. & Nekaris, K.A.I. (2015). Does toxic defence in Nycticebus spp. relate to ectoparasites? The lethal effects of slow loris venom on arthropods. Toxicon. 95: pp. 1-5
  4. Hagey, L.R., Fry, B.G. & Fitch-Snyder, H. (2007). Talking Defensively: A Dual Use for the Brachial Gland Exudate of Slow and Pygmy lorises. In Gursky, S.L. & Nekaris, K.A.I. (Eds.), Primate Anti-Predator Strategies. Springer, Boston, MA. pp. 253-272.
  5. Inoue, F., Inoue, A., Tsuboi, T., Ichikawa, T., Suga, M., Ishihara, S. & Nakayama, S. (2021). Severe Anaphylactic Shock Following a Slow Loris Bite in a Patient with Cat Allergy. Intern Med . 60: pp. 3037-3039
  6. Ishida, H., Hirasaki, E. & Matano, S. (1992). Locomotion of the slow loris between discontinuous substrates. Topic in primatology. In Matano, S., Tuttle, R.H., Ishida, H. & Goodman, M. (Eds.), Evolutionary Biology, Reproductive Endocrinology, and Virology, volume 3. Tokyo: University of Tokyo Press. pp. 139-152.
  7. Krane, S., Itagaki, Y., Nakanishi, K. & Weldon, P.J. (2003). “Venom” of the slow loris: sequence similarity of prosimian skin gland protein and Fel d 1 cat allergen. Naturwissenschaften. 90 (2): pp. 60-62
  8. Matthew, G., Ariana, W., Stephanie, A.P., Nancy, G. & Nekaris, K.A.I. (2018). Survey of practitioners handling slow lorises (Primates: Nycticebus): an assessment of the harmful effects of slow loris bites. Journal of Venom Research. 9: pp. 1-7
  9. Md-Zain, B.M., Mohhoyua, K.S., Aifat, N.R., Ngadi, E., Ayob, N., Rovie-Ryan, J.J., Ampeng, A., Mohd-Ridwan, A.R., Blair, M.E. & Abdul-Latiff, M.A.B. (2019). Molecular data confirm the presence of Nycticebus bengalensis on Langkawi Island, Malaysia. Biodiversitas. 20 (4): pp. 1115-1120
  10. Nekaris, K.A.I., Moore, R.S., Rode, E.J. & Fry, B.G. (2013). Mad, bad and dangerous to know: the biochemistry, ecology and evolution of slow loris venom. Journal of Venomous Animals and Toxins including Tropical Diseases. 19: pp. 1-10
  11. Nekaris, K.A.I., Stephanie, A.P. & Streicher, U. (2020). Nycticebus coucang. The IUCN Red List of Threatened Species 2020: e.T163017685A17970966. Retrieved March 22, 2021, from
  12. Roos, M.C., Boonratana, R., Supriatna, J., Fellowes, J.R., Groves, C.P., Nash, S.D., Rylands, A.B. & Mittermeier, R.A (2014). An updated taxonomy and conservation status review of Asian primates. Asian Primates Journal. 4 (1): pp. 2-38
  13. Rovie-Ryan, J.J., Gani, M., Lee, Y.P., Gan, H.M. & Abdullah, M.T. (2018). Rediscovery of Nycticebus coucang insularis Robinson, 1917 (Primates: Lorisidae) at Tioman Island and its mitochondrial genetic assessment. Sains Malaysiana. 47 (10): pp. 2533-2542
  14. Rovie-Ryan, J.J., Gani, M., Lee, Y.P., Gan, H.M. & Abdullah, M.T. (2019). Mitogenome data of Nycticebus coucang insularis Robinson, 1917 (Primate: Lorisidae). Data in Brief . 25: pp. 104058
  15. Utami, S.S. & Van Hooff, J.A.R.A.M. (1997). Meat-eating by adult female Sumatran orangutans (Pongo pygmaeus abelii). Am. J. Primatol . 43: pp. 159-165
  16. Utap, M.S. & Mohd Jamal, M.S. (2019). Anaphylactic shock following a bite of a wild Kayan slow loris (Nycticebus kayan) in rural Sarawak, Malaysian Borneo. Rural and Remote Health. 19: pp. 5163
  17. Weinstein, S.A., White, J., Keyler, D.E. & Kardong, K.V. (2013). Response to Jackson et al. (2012). Toxicon. 64: pp. 116-127
  18. Wiens, F. (February 2002). Behavior and Ecology of Wild Slow Lorises (Nycticebus coucang): Social Organization, Infant Care System, and Diet (Doctoral Dissertation, Bayreuth University, Bavaria, Germany). Retrieved March 22, 2021, from
  19. Wiens, F., Zitzmann, A. & Hussien, N. A. (2006). Fast food for slow lorises: Is low metabolism related to secondary compounds in high-energy plant diet? Journal of Mammalogy. 87 (4): pp. 790-798
  20. Wilde, H. (1972). Anaphylactic shock following bite by a ‘slow loris’, Nycticebus coucang. Am. J. Trop. Med. Hyg. 21 (5): pp. 592-594
  21. Wirdateti, W., Lilik, E.S., Suparno, S. & Tri Hadi, H. (2005). Feeding and habitat of slow Loris (Nycticebus coucang) in Badui Tribe conservation forest, Rangkasbitung-south Banten. Biodiversitas. 6 (1): pp. 45-49
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