Chelicera
A pair of front appendages in chelicerates, positioned ahead of the mouth and used to seize, pierce, cut, or otherwise handle food.
Chelicerata: An arthropod subphylum whose members lack antennae and bear chelicerae as their first pair of appendages. Chelicerae are the defining first appendages of this arthropod group.
Cheliceral fang: A pointed terminal part of a chelicera, especially in spiders, used to pierce prey and deliver venom. Spider fangs are a specialized form of cheliceral tip.
Spider: An arachnid with four pairs of walking legs and chelicerae that commonly bear fangs. Spiders provide the familiar example of chelicerae modified for venomous prey capture.
Arthropod head problem: The evolutionary challenge of identifying how segments and appendages correspond across arthropod lineages. Chelicerae occupy a head segment whose homology has been debated.
Arthropod: An invertebrate animal with a segmented body, jointed appendages, and a chitinous exoskeleton. Chelicerae are specialized jointed appendages within the arthropod body plan.
Venom: A secretion delivered by an animal through a bite, sting, or other specialized structure to affect another organism. In many spiders, chelicerae inject venom through their fangs.
Scorpion: An arachnid with grasping pedipalps, a segmented tail, and chelicerae used to tear food. Scorpions use small chelicerae to process prey alongside their prominent pincers.
Hox gene: A developmental regulatory gene that helps assign identities to body regions along an animal's main axis. Hox expression helps explain the distinct developmental identity of chelicerate appendage-bearing segments.
Pedipalp: The second pair of appendages in chelicerates, often used for sensing, prey handling, or reproduction. Pedipalps sit directly behind chelicerae and are easily confused with them.
Spider silk: A protein fiber spun by spiders from specialized abdominal glands for webs, prey capture, or other functions. Chelicerae manipulate silk during prey wrapping and feeding.