Cephalothorax

 ( Arthropod Anatomy ) 

The cephalothorax, also called prosoma in some groups, is a tagma of various , comprising the head and the thorax fused together, as distinct from the abdomen behind.

(The terms prosoma and opisthosoma are equivalent to cephalothorax and abdomen in some groups. The terms prosoma and opisthosoma may be preferred by some researchers in cases such as arachnids, where there is neither fossil nor embryonic evidence animals in this class have ever had separate heads and thoraxes, and where the opisthosoma contains organs atypical of a true abdomen, such as a heart and respiratory organs.

Shultz, Stanley; Shultz, Marguerite (2026). 9780764138850, Barron's. ISBN 9780764138850

) The word cephalothorax is derived from the Greek language words for head (κεφαλή]], kephalé) and thorax (θώραξ, thórax]]).

Timothy J. Gibb & C. Y. Oseto (2026). 9780123695451, Academic Press. ISBN 9780123695451

This fusion of the head and thorax is seen in Chelicerata and ; in other groups, such as the Hexapoda (including ), the head remains free of the thorax. An exception is females in Stylopidia, a clade in the order Strepsiptera, a group of highly specialised parasitic insects. A generic classification of Xenidae (Strepsiptera) based on the morphology of the female cephalothorax and male cephalotheca with a preliminary checklist of species In and many , a hard shell called the carapace covers the cephalothorax.

Andrew J. Martinez (2026). 9781881652328, Aqua Quest Publications. ISBN 9781881652328

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Arachnid anatomy

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Fovea

The fovea is the centre of the cephalothorax and is located behind the head (only in spiders).Dalton, Steve (2008). Spiders; The Ultimate Predators. A & C Black, London. P.p. 19. . It is often important in identification. It can be transverse or procurved Smith, A. M. (1990c). Baboon spiders: Tarantulas of Africa and the Middle East. Fitzgerald Publishing, London, pp. 138. Retrieved February 13, 2016. and can, in some tarantulas (e.g. Ceratogyrus darlingi) have a "horn".

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Clypeus

The clypeus is the space between the anterior of the cephalothorax and the ocularium. It is found in most arachnids. It is connected to the labrum of the invertebrate, between the labrum and the face.

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Ocularium

The ocularium is a "turret" for the ocellus found in most arachnids. Spiders... Yorkshire Naturalists' Union. Retrieved February 13, 2016. In harvestman, it may have the ornament of spines.Sankey, John & Savory, Theodore. British Harvestmen. Academic Press. P.p. 1–75. .

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Trident

The trident is a small group of (usually three) spines found in harvestmen exclusively. It is located in front of the ocularium. It varies in size amongst species; in some it is completely absent, and in others it is enlarged considerably.

Categories: Arthropod Anatomy

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