Chelicerae. Organ that in arachnids replaces the antennae .
Summary
- 1 Chelicera
- 2 Types of chelicerae
- 1 Description
- 3 Fountains
chelicerae
Each of the paired and prehensile function appendages , characteristic of chelicerates . Organ that in arachnids replaces the antennae .
Types of chelicerae
Description
*Knife chelicerae: These types of chelicerae resemble a folding razor and can be considered subchelate. It is made up of two knuckles and is exclusive to Tetrapulmonata . They consist of a basal knuckle that articulates with the cephalothorax and another fang-shaped apical knuckle that articulates with the basal knuckle. They present two different forms: orthognathous and labidognathous. The orthognathic chelicerae articulate in such a way as to allow them to move parallel to the axis of the body. This type of chelicerae occurs in spiders Liphistiomorphae and Mygalomorphae and in the closely related orders Amblypygi , Schizomida and Uropygi(Thelyphonida). The labidognathic chelicerae move at right angles to the axis of the body; are characteristic of the araneomorphic spiders Araneomorphae.
*Scissor chelicerae: Scissor chelicerae are chelate-shaped and are made up of two knuckles. They occur in the orders pseudoscorpiones and solifuges.
*Claw chelicerae : This is the primitive condition and occurs in palpigrades, scorpions and harvestmen. They are found in other non-arachnid chelicerates, such as the Xiphosura and Eurypterida . Perhaps the cheliphores of the pycnogonids are homologues of this type of chelicerae and should be considered here.