They Pack a Venomous Bite, and Other Interesting Facts About the Pygmy Slow Loris

They Pack a Venomous Bite, and Other Interesting Facts About the Pygmy Slow Loris

Pygmy slow lorises are nocturnal, wide-eyed primates that spend most of their time in trees. Native to Vietnam, Cambodia, Laos, and China, their pygmy name is apt. They top out at about 10 inches in length and two pounds in weight, though most weigh about half that.

The “loris” part of their name is also appropriate, coming from an old Dutch word meaning clown. That’s likely due to their natural eye “makeup” looking a little bit like they might be ready to join the circus. These markings surround large eyes that help them hunt their favorite prey – insects and small mammals and birds – in the dark. They also eat fruit, tree gum, and sap.

Unfortunately, this species is listed as endangered on the International Union for Conservation of Nature’s Red List. The main threat? People. Learn more about this unique species that could use our help.

They Have Unique Bodies

The pygmy slow loris has an extra tongue. The larger upper tongue is used to slurp up nectar, while the lower acts as a toothbrush after they’ve finished their meal. Their back is also out of the ordinary. They have extra vertebrae, which allows them to move like snakes.

They’re the Only Venomous Primate

Their slithering movements aren’t the only way they’re similar to snakes. Slow lorises are also venomous, like many of their scaled neighbors. They’re the only primate and one of the few mammals with this attribute. They have a toxic oil located in glands near their elbows. When they lick this oil and it mixes with their saliva, it becomes venom. The venom then spreads to their teeth, producing a dangerous and sometimes deadly bite. Grooming their babies with this venom can also protect them from predators.

They May Fight Dirty

Slow lorises don’t just use that venom to fight off predators from other species. Research has found they most often use it against each other. Anna Nekaris from Oxford Brookes University led a study on Javan slow lorises in Indonesia that involved eight years of observing the species. Her team found that about a third of females and a little more than half of males showed signs of a toxic loris bite. Symptoms include the loss of large patches of skin and fur, and sometimes fingers and toes. Ultimately, the bites can also be fatal.


The thought is that these intraspecies bites stem from territorialism in the species, as well as their protection of mates and offspring. Nekaris told Mongabay that they’re “adorable little furballs of death.”

They Can Be Social, Though

Despite the fact that they’re somewhat solitary in the wild – which isn’t surprising considering the prior fact – when they end up in captivity, they can make “friends.” Pygmy slow lorises are often victims of the pet trade, and when rescued, they can find themselves in zoos or other wildlife rescues. A 2021 study of six female pygmy slow lorises at the Japan Monkey Centre’s Slow Loris Conservation Centre found that all-female groups are social and prefer to remain close to each other, even when nesting at night. The researchers say this suggests females of the species may seek out companionship when it’s available.

They Snooze in an Endearing Way

Since pygmy slow lorises are nocturnal, they spend the day sleeping in trees. The position is kind of cute, though. They’ll usually sleep curled up into a ball with their heads tucked under their arms. They’ll do this in the hollows of trees, in tree crevices, or on branches.

They’re Also Up for Hanging Out

While they’re up in the trees, they make the most of branches. Though they’re small, they have remarkably strong limbs. They can hang from a branch with their hind legs for hours at a time. They may do this while gathering food. The San Diego Zoo says they avoid having circulation issues in this position due to extra vascular bundles in their limbs that allow blood to flow to their extremities.

They’re Double Trouble

Offspring can be twice the fun for pygmy slow loris mothers. Having twins is a common experience for this species. They may have more in captivity, though. In the wild, as was mentioned before, the mother can use her venom to keep her young safe as she goes to forage for food. So even their babies can pack a venomous punch.

They Hibernate... Sort Of

While they may not knock out for months during the winter like true hibernators, pygmy slow lorises do partake in a lesser version of hibernation: torpor. They’ll do this when resources are scarce in order to save energy. When they enter this state, their metabolism slows and their body temperature falls, just like in hibernators.

A 2015 study on the topic found that this torpor can last for periods of up to 63 hours. The study authors note that the pygmy slow loris is the only primate species outside of Madagascar found to utilize torpor/hibernation in the colder months.

They May Be Beneficial to the Environment

Research has indicated that the pygmy slow loris provides benefits to its environment. First, it eats insects, keeping their numbers at manageable levels. Secondly, it may potentially play a role in seed dispersal due to its fruit intake.

They Face Threats

Like so many unique species, the pygmy slow loris faces many threats to its survival, which has led to its endangered status on the IUCN Red List. Due to its “cuteness” factor, the species is caught up in the pet trade. When people sell them as pets, they will often remove their teeth to take away their venomous bite. This can lead to serious health issues including malnutrition and infections. Many of these animals will also die.

They’re also used in traditional medicine and are faced with habitat loss.

We’re working to help the pygmy slow loris and other threatened Vietnamese wildlife through Greater Good Charities’ Global Discovery Expeditions program, which supports scientists as they do survey work in biodiverse regions, including Vietnam. If you’d like to help, learn how here!

Michelle Milliken

Michelle has a journalism degree and has spent more than seven years working in broadcast news. She's also been known to write some silly stuff for humor websites. When she's not writing, she's probably getting lost in nature, with a fully-stocked backpack, of course.

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