Which primate is the only one known to be venomous?

The only primate known to be venomous is the slow loris. Slow lorises belong mainly to the genus Nycticebus and are nocturnal, tree-dwelling primates found across parts of South and Southeast Asia.

Their unusual chemical defense begins with a brachial gland on the upper arm. A slow loris licks the gland’s secretion and mixes it with saliva, producing a toxic mixture that can be delivered through a bite. The venom may deter predators, defend young, and help settle conflicts between lorises over mates, food, or territory.

This is not the same as being poisonous. Poison harms an animal when eaten or touched, while venom is actively delivered, in this case through the bite. Slow loris bites can cause severe pain, swelling, tissue damage, and in rare cases dangerous allergic reactions in humans.

A common misconception comes from viral videos showing apparently calm lorises. Their motionless behavior is often a defensive response, not evidence that they are suitable pets. The animals are protected in many countries, and the exotic-pet trade causes serious welfare problems.