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The chelicerae (/ k ə ˈ l ɪ s ər iː /) are the mouthparts of the subphylum Chelicerata, an arthropod group that includes arachnids, horseshoe crabs, and sea spiders. Commonly referred to as " jaws ", chelicerae may be shaped as either articulated fangs , or as a type of pincers .
The chelicerae ("claw horns") that give the sub-phylum its name normally consist of three sections, and the claw is formed by the third section and a rigid extension of the second. [ 13 ] [ 20 ] However, spiders' have only two sections, and the second forms a fang that folds away behind the first when not in use. [ 17 ]
Carnivores have chelicerae that tear and crush prey, whereas herbivores can have chelicerae that are modified for piercing and sucking (as do parasitic species). In sea spiders, the chelicerae (also known as chelifores) are short and chelate and are positioned on either side of the base of the proboscis or sometimes vestigial or absent.
Chelicera (plural chelicerae): One of two appendages at the front of the carapace, made up of basal portion, the paturon, and the fang; [5] sometimes called the jaw; see also Chelicerae; Cheliceral furrow: A shallow groove on the basal portion of a chelicera accommodating the fang, usually having teeth on its margins [6]
The cephalothorax, also called prosoma, is composed of two primary surfaces: a dorsal carapace and a ventral sternum.Most external appendages on the spider are attached to the cephalothorax, including the eyes, chelicerae and other mouthparts, pedipalps and legs.
The first of these are the chelicerae, which give chelicerates their name. In horseshoe crabs, these look like tiny pincers in front of the mouth. [25]: 555 Behind the chelicerae are the pedipalps, which are primarily used as legs. In the final molt of males, the ends of the pedipalps are modified into specialized, grasping claws used in mating.
And three-segmented chelicerae is the ancestral condition in Parasitiformes, but has been reduced to just two segments in more derived groups. [18] The pedipalps differ between taxa depending on diet; in some species the appendages resemble legs while in others they are modified into chelicerae-like structures.
The chelicerae, which are very sharp, are used to pull small amounts of food off the prey item into a pre-oral cavity below the chelicerae and carapace. The digestive juices from the gut are egested onto the food, and the digested food is then sucked into the gut in liquid form.