from The American Heritage® Dictionary of the English Language, 4th Edition
- n. The anterior or cephalic portion of the body of certain invertebrates, such as arachnids, in which segmentation is not evident.
from Wiktionary, Creative Commons Attribution/Share-Alike License
- n. The front segment of a body which is divided into two or more segments, especially the cephalothorax of an arachnid.
from the GNU version of the Collaborative International Dictionary of English
- n. The anterior of the body of an animal, as of a cephalopod; the thorax of an arthropod.
from The Century Dictionary and Cyclopedia
- n. The anterior or cephalic section of the body of a cephalopod, bearing the rays or arms; the head or anterior part of any mollusk, in advance of the mesosoma.
- n. In dimyarian lamellibranchs, a region of the body in which is the anterior adductor muscle, and which is situated in front of the mouth: it is succeeded by the mesosoma.
- n. In Cirripedia, the wide part of the body, preceding the thoracic segments: in the barnacle, for example, that part which is situated immediately behind the point of attachment of the body to the shell on the rostral side. Darwin. See cuts under Balanus and Lepadidæ.
Attached to the prosoma are the bird eater's eight legs, their pedipalps and two chelicerae's.
All of these groups share a similar body architecture, being divided into an anterior prosoma (the cephalothorax) and a posterior opisthosoma (abdomen).
Tarantulas have two body parts viz. the prosoma (cephalothorax) and the opisthososma (abdomen) that are connected via the pregenital somite (pedicle).
This is a result of the tarantula's mouth, located under the chelicerae on the front lower part of the spiders prosoma, is just a short straw tube that can only pass liquid through.
The peclide is what allows the two bodies to move, it is attached to the prosoma and allows the opisthosoma to twist in a waist like motion.
The prosoma is also known as the cephalthoray, while the abdomen is known as the opisthosoma.