Toxicological Trivia from December 15, 2009: An animal may be poisonous to humans through various mechanisms, for example by inoculation (venomous animals). This requires the existence of some element that specializes in animal anatomy, which have specific names, eg chelicerae belongs to:
a) Spiders;
b) The snakes;
c) Some insects.

Correct Answer a. Read more in monograph in Spanish: Basics "Venomous Animals of Argentina. Items for recognition and first aid measures in case of accidents (2006). See also in Wikipedia: The chelicerae (pronounced /kəˈlɪsəri/) are mouth parts of the Chelicerata, an arthropod subphylum that includes arachnids, Merostomata (horseshoe crabs), and Pycnogonida (sea spiders). Chelicerae are pointed appendages which are used to grasp food, and are found in place of the chewing mandibles most other arthropods have. Additionally, some chelicerae, such as those found in spiders, are hollow and contain (or are connected to) venom glands, and are used to inject venom into prey or a (perceived) threat.