What does prosoma mean?
A prosoma is the anterior or front section of an arthropod's body. It contains important sensory and feeding structures, especially the eyes and mouthparts, and in many arachnids also supports the first pair of legs. The term is especially common in descriptions of spiders, scorpions, mites, and related animals. In a spider, the prosoma is connected to the abdomen by a narrow stalk-like pedicel, making the division between the two regions particularly visible. Prosoma should not be confused with the opisthosoma, the posterior part of the body, or with cephalothorax, a related but broader term for a head and thorax combined into one region. For most general readers, the word is mainly useful when reading specialist descriptions of animal anatomy.
nounThe front or anterior portion of the body of an arthropod, bearing the eyes and mouth and usually fused with the first pair of appendages. In many arachnids, it is the part of the body in front of the narrow pedicel.
- The anterior division of an arthropod's body, bearing the eyes and mouth and typically the first pair of appendages.
"The prosoma of the spider contains its eyes, mouthparts, and first pair of legs."
"The spider's prosoma is joined to its abdomen by a narrow pedicel."
"In a scorpion, the prosoma bears the chelicerae, pedipalps, and walking legs."
Plural is used in technical zoological contexts, especially for the anterior body regions of multiple arthropods.
"The prosomata of the two specimens differ in size."
In a spider, the prosoma is the front-facing “head” region: it carries the eyes and mouthparts and anchors the first pair of legs.
Reviewed by Deb Chak, Editor. AI-assisted content curated by RJS Tech Solutions LLP.
Where does prosoma come from?
The word comes from Greek prós, meaning “forward” or “before,” and sōma, meaning “body.” Its development reflects its anatomical use: the term names the forward-facing part of an arthropod's body. English zoological usage developed alongside other technical anatomical terms built from Greek roots, including somatic and prosomium.
Related word forms
How prosoma is actually used
Primarily a technical zoological term. It is most often used for arachnids and other arthropods whose body is divided into recognizable anterior and posterior regions.
Easily confused with prosoma
The prosoma is the front body region bearing the eyes and mouth, whereas the opisthosoma is the posterior region behind it.
Cephalothorax is a broader term for a combined head and thorax, while prosoma specifically names the anterior body region of an arthropod.