The slow loris is the only known venomous primate, using a toxic bite for defense.
Slow lorises are nocturnal primates found in the rainforests and other tropical forests of South and Southeast Asia. They produce venom by mixing saliva with a secretion from glands on their upper arms. When threatened, a slow loris may raise its arms, collect the secretion, and deliver it through a bite.
The venom can cause severe pain, swelling, tissue damage, and, in rare cases, serious allergic reactions in humans. It also helps slow lorises deter predators and may play a role in conflicts between individuals. Their slow, deliberate movements and strong grip suit life among branches.
“Venomous” means that the animal actively delivers toxins, usually by biting; “poisonous” generally means toxins harm an animal that touches or eats them. Slow lorises are not the only mammals with toxins, but they are the only primates confirmed to have a venomous bite.