--- title: "Sunda Slow Loris (Nycticebus coucang) | AnimalTracks.wiki" description: "The deceptively cute nocturnal primate whose elbow-gland secretion carries a protein closely resembling a cat allergen." image: "https://animaltracks.wiki/images/animals/sunda-slow-loris-1.webp" published: "2026-09-05" updated: "2026-09-27" --- # Sunda Slow Loris (*Nycticebus coucang*) > **Status**: Checked against 7 sources, listed under Sources below. > **Tagline**: The deceptively cute nocturnal primate whose elbow-gland secretion carries a protein closely resembling a cat allergen. > **Soundtrack Vibe**: Trip-Hop & Eerie Downtempo // Sneaker Pimps, "6 Underground" > **Soundtrack Links**: [Spotify](https://open.spotify.com/track/5SJ7mZ4HZWbhFcHpBvHU55) | [YouTube](https://www.youtube.com/watch?v=OL4gpjoSeI4) > **Vibe Match**: Hypnotic, eerie and deceptively gentle, like a primate that arms its bite by raising its arms above its head and mixing the oil from a gland on its upper arm with its saliva. ## Biological Superpowers & Stats - **Taxonomy**: *Nycticebus coucang* - **Danger Level**: Extreme - **Conservation Status**: Endangered ([IUCN Red List](https://doi.org/10.2305/iucn.uk.2020-2.rlts.t163017685a17970966.en)) - **Superpower**: Brachial gland chemical weaponization and specialized toothcomb venom delivery - **Habitat**: Mainly primary and secondary lowland tropical forests of Indonesia, Malaysia, southern Thailand and Singapore - **Diet**: Sap, gum, nectar, stems and fruit, occasionally spiders and insects; also seen eating snails and bird eggs - **Tags**: rainforest, venomous, nocturnal, mammal, tree-dweller ## Natural History & Behavior ## A Primate With a Venomous Bite Found mainly in Sumatra and nearby islands, Peninsular Malaysia, southern Thailand and Singapore, the **Sunda Slow Loris** (*Nycticebus coucang*) looks harmless: large eyes, thick fur, and a tail reduced to a stump hidden in that fur. It measures 27 to 38 centimetres and weighs 599 to 685 grams, and the oldest confirmed record, a captive animal, lived 25.8 years. Slow lorises, the genus *Nycticebus*, are the only primates known to harbour toxins. ## An Elbow Gland and a Toothcomb In this species the toxins are thought to come from the **brachial gland**, a bare, gland-studded patch of skin on the inside of the arm that the loris licks during grooming. In the classic slow loris defence posture, a threatened animal usually raises its arms above its head and moves its mouth to the gland to combine the fluid with saliva, then either applies the mixture to the top of its head or keeps it in its mouth to bite. A slow loris's toothcomb conducts the liquid upward, which makes it an effective venom delivery system. A major protein in the gland's secretion, about 18 kilodaltons and built from two chains, shows nearly 70 percent sequence similarity at the start of each chain with Fel d 1, the major allergen from domestic cats. The researchers who isolated it suggest this may explain why bites do harm. Across the genus, bites are intensely painful in both humans and other lorises, can cause swelling and wounds that take weeks to heal, and in extreme cases may trigger anaphylactic shock, sometimes resulting in death. One research team, pointing to other serpentine features of slow lorises such as an extra vertebra in the spine that gives snake-like movement, proposes that the venom may have evolved as mimicry of the spectacled cobra. > **A Toxic Babysitter** Before and during weaning, a mother licks her young, covering them in toxic oil so they may be protected while she leaves to forage. ## What It Eats and What Eats It The Sunda slow loris is a dietary generalist, feeding on sap, gum, nectar, stems, fruit and occasionally spiders and insects. Roughly a third of its diet is sap and gum, another third is nectar and nectar-producing plants, and approximately a quarter is fruit. Its predators include reticulated pythons and changeable hawk-eagles. At Ketambe in Indonesia, researchers recorded one Sumatran orangutan mother and infant eating slow lorises on three occasions, which they called rare. If threatened, the loris rolls into a ball, leaving nothing but toxic fur exposed, and may drop from the tree if the predator is arboreal. It may also bite, though this is very rare next to such passive defences. ## A Rainforest Species Losing Ground The Sunda slow loris is listed **Endangered** on the IUCN Red List. Illegal harvesting and trade are major forces behind declines of wild slow lorises, and habitat loss and degradation over large areas of this species' range have caused large declines too. A study of 77 greater slow lorises, as this species is also called, confiscated en masse and brought to Cikananga Wildlife Center in Indonesia found that 28.6 percent died within the first six months, mostly from traumatic injury, and all the infants died. ## Frequently Asked Questions ### How does the Sunda slow loris produce and deliver its venom? In slow lorises the venom is activated by combining oil from the brachial gland, on the inside of the elbow, with saliva. A threatened loris usually raises its arms above its head and brings its mouth to the gland, then either applies the mixture to the top of its head for defence or keeps it in its mouth to bite. *(Source: [Nekaris et al. 2013]())* ### What happens if a slow loris bites a person? Bites on people are painful and have caused anaphylaxis. A major protein in the Sunda slow loris's elbow-gland secretion shows nearly 70 percent sequence similarity, at the start of its two chains, with Fel d 1, the major allergen from domestic cats. The researchers who found it suggest the two proteins may cross-react in the immune system, a possible explanation for the harm a bite does. *(Source: [Krane et al. 2003]())* ### Why does the slow loris raise its arms over its head when threatened? It is the classic slow loris defence posture: with its arms above its head, a loris can quickly move its mouth to the brachial gland and combine the gland's fluid with saliva. Researchers have also remarked on how snake-like the defensive postures of lorises are. One team, noting serpentine features such as an extra vertebra in the spine that gives snake-like movement, has proposed that slow loris venom may have evolved as mimicry of the spectacled cobra. *(Source: [Nekaris et al. 2013]())* ## Sources 1. [Nycticebus coucang (slow loris). Animal Diversity Web, University of Michigan.]() 2. [AnAge entry for Nycticebus coucang. AnAge: The Animal Ageing and Longevity Database, Build 15.]() 3. [Nekaris, Poindexter & Streicher (2020). Nycticebus coucang. The IUCN Red List of Threatened Species 2020: e.T163017685A17970966.]() 4. [Nekaris et al. (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.]() 5. [Krane et al. (2003). "Venom" of the slow loris: sequence similarity of prosimian skin gland protein and Fel d 1 cat allergen. Naturwissenschaften.]() 6. [Hardus et al. (2012). Behavioral, Ecological, and Evolutionary Aspects of Meat-Eating by Sumatran Orangutans (Pongo abelii). International Journal of Primatology.]() 7. [Fuller et al. (2017). Welfare impacts of the illegal wildlife trade in a cohort of confiscated greater slow lorises, Nycticebus coucang. Journal of Applied Animal Welfare Science.]() *Published September 5, 2026. 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