The slow loris may have gained popular fame through YouTube videos in which terrified lorises grasp umbrellas, but it's actually a fascinating animal even when it's not fearing for its life. (Yep, that's what's going on in those videos: when threatened, lorises become docile and passive, which is different from being friendly. Oh, and the pet trade in lorises is brutal and horrifying, just FYI.) It's one of very few venomous mammals and even fewer venomous primates; it has a poison gland on its elbow which it licks to mix with its saliva, giving it a venomous bite. It also has a highly peculiar arrangement of blood vessels in its hands and feet, so that it can grasp branches for hours on end, supporting its own weight, without losing sensation.