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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.
In animals like whip scorpions and whip spiders the first two 'sternites' bearing the book lungs may actually be highly modified opisthosomal limbs. Segmentation of the opisthosoma in adult spiders is not visible, but embryo spiders typically have 13 segments, the posterior segments being called the presegmental zone.
The cephalothorax, also called prosoma in some groups, is a tagma of various arthropods, comprising the head and the thorax fused together, as distinct from the abdomen behind. [1] The terms prosoma and opisthosoma are equivalent to cephalothorax and abdomen in some groups.
Cephalothorax or prosoma: One of the two main body parts , located towards the anterior end, composed of the head (cephalic region or caput) and the thorax (thoracic region), the two regions being separated by the cervical groove; covered by the carapace and bearing the eyes, legs, pedipalps and mouthparts [3]
When a spider bites, the two parts of the chelicerae come together like a folding knife, and when making a threat display or actually preparing to bite, the spider will open the angle of the fangs with the basal portion of the chelicerae and also open the angle of the basal portion with the cephalothorax. [2]
The bodies of many arachnids, such as spiders, have two tagmata, as do the bodies of some crustaceans: in both groups the anterior tagma may be called the cephalothorax (meaning head plus chest) or the prosoma or prosome (meaning "fore-part of body"). The posterior tagma may be called the abdomen.
In crustaceans, the carapace functions as a protective cover over the cephalothorax (i.e., the fused head and thorax, as distinct from the abdomen behind). Where it projects forward beyond the eyes, this projection is called a rostrum. The carapace is calcified to varying degrees in different crustaceans. [1]
A spider's body comprises two regions: the prosoma or cephalothorax (anterior end) and the opisthosoma or abdomen (posterior end). [5] Both regions are responsible for their own functions and are linked by a narrow stalk called a pedicel. [5] The prosoma is segmented and protected by the sternum, carapace, and a plate on the dorsal and ventral ...