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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.
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]
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.
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 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. [3]
The extant chelicerates comprise two marine groups: Sea spiders and horseshoe crabs, and the terrestrial arachnids. These have been thought to be related as shown below. [41] [44] (Pycnogonida (sea spiders) may be excluded from the chelicerates, which are then identified as the group labelled "Euchelicerata". [46]) A 2019 analysis nests ...
A spider could also simply climb into someone's mouth. But Rod Crawford, arachnid curator at the Burke Museum, said "spiders probably find sleeping humans terrifying" because we "create vibrations ...
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]