Editing Cephalothorax

{{short description|Arthropod tagma}}
{{for|cephalothoracic humans|Headless men}}
[[File:General malacostracan en.svg|thumb|''[[Bauplan]]'' of a [[malacostraca]]n; the '''cephalothorax''' is the region including cephalon and thorax, marked in yellow.|upright=1.2]]
The '''cephalothorax''', also called '''prosoma''' in some groups, is a [[Tagma (biology)|tagma]] of various [[arthropod]]s, comprising the head and the [[Thorax (arthropod anatomy)|thorax]] fused together, as distinct from the [[Abdomen#Arthropoda|abdomen]] behind.<ref name="Biology">{{cite book |author=Eldra Pearl Solomon, Linda R. Berg & Diana W. Martin |year=2004 |title=Biology |edition=7th |publisher=[[Cengage Learning]] |isbn=978-0-534-49276-2 |chapter=The animal kingdom: an introduction to animal diversity |pages=534–549 |chapter-url=https://books.google.com/books?id=UCUxpgfcoNsC&pg=PA573}}</ref> (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.<ref>{{cite book |author=Shultz, Stanley; Shultz, Marguerite |year=2009 |title=The Tarantula Keeper's Guide |publisher=Barron's |pages=23 |isbn=978-0-7641-3885-0}}</ref>) The word ''cephalothorax'' is derived from the [[Greek language|Greek]] words for head ({{lang|el|[[:wikt:κεφαλή|κεφαλή]]}}, ''{{lang|el|kephalé}}'') and thorax ({{lang|el|θώραξ}}, ''{{lang|el|[[:wikt:thorax|thórax]]}}'').<ref>{{cite book |author=Timothy J. Gibb & C. Y. Oseto |year=2006 |title=Arthropod Collection and Identification: Field and Laboratory Techniques |publisher=[[Academic Press]] |isbn=978-0-12-369545-1 |chapter=Glossary |chapter-url=https://books.google.com/books?id=qwO-9ElVPlMC&pg=PT180}}</ref> This fusion of the head and thorax is seen in [[Chelicerata|chelicerates]] and [[crustacean]]s; in other groups, such as the [[Hexapoda]] (including [[insect]]s), the head remains free of the thorax.<ref name="Biology"/> In [[horseshoe crab]]s and many [[crustacean]]s, a hard shell called the [[carapace]] covers the cephalothorax.<ref>{{cite book |author=Andrew J. Martinez |year=2003 |title=Marine Life of the North Atlantic: Canada to New England |edition=3rd |publisher=[[Aqua Quest Publications]] |isbn=978-1-881652-32-8 |chapter=Arthropoda (crabs, shrimps, lobsters) |pages=144–175 |chapter-url=https://books.google.com/books?id=dq-iIBVn4_MC&pg=PA144}}</ref>

==Arachnid anatomy==

===Fovea===
The fovea is the centre of the cephalothorax and is located behind the head (only in spiders).<ref name = dalton2008>Dalton, Steve (2008). ''Spiders; The Ultimate Predators''. A & C Black, London. P.p. 19. {{ISBN|9781408106976}}.</ref> It is often important in identification. It can be transverse or procurved <ref name = smith1990>Smith, A. M. (1990c). Baboon spiders: Tarantulas of Africa and the Middle East. Fitzgerald Publishing, London, pp. 138. Retrieved February 13, 2016.</ref> and can, in some [[tarantulas]] (e.g. ''[[Ceratogyrus darlingi]]'') have a "horn".<ref name = gallon2008>{{cite journal |last1=Gallon |first1=R.C. |date=2008 |title=On some poorly known African Harpactirinae, with notes on ''Avicuscodra arabica'' Strand, 1908 and ''Scodra pachypoda ''Strand, 1908 (Araneae, Theraphosidae) |journal=Bulletin of the British Arachnological Society |volume=14 |page=238 }}</ref>

===Clypeus===
{{Main|Clypeus (arthropod anatomy)}}

The clypeus is the space between the anterior of the cephalothorax and the ocularium. It is found in most arachnids.<ref name = smith1990/> It is connected to the labrum of the invertebrate, between the labrum and the face.

===Ocularium===   
The ocularium is a "turret" for the [[ocellus|ocelli]] found in most arachnids.<ref name = ynu>[http://www.ynu.org.uk/insects/spiders Spiders...] {{Webarchive|url=https://web.archive.org/web/20211128061345/https://www.ynu.org.uk/insects/spiders |date=2021-11-28 }} [[Yorkshire Naturalists' Union]]. Retrieved February 13, 2016.</ref> In [[harvestman|harvestmen]], it may have the ornament of spines.<ref name = sankeysavory1974>Sankey, John & Savory, Theodore. ''British Harvestmen''. Academic Press. P.p. 1–75. {{ISBN|012619050X}}.</ref>

===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.<ref name = sankeysavory1974/>

==References==
{{Portal|Arthropods}}
{{reflist|32em}}

[[Category:Arthropod anatomy]]


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