Carapace#Arachnid
{{Short description|Part of exoskeleton in some animals}}
{{Use dmy dates|date=April 2021}}
{{redirect|Cephalic shield|the head shield in arthropods|Cephalon (arthropod head)}}
File:Penaeus diagram carapace.png, with the carapace highlighted in red]]
A carapace is a dorsal (upper) section of the exoskeleton or shell in a number of animal groups, including arthropods, such as crustaceans and arachnids, as well as vertebrates, such as turtles and tortoises. In turtles and tortoises, the underside is called the plastron. In botany, a carapace refers to the hard outer cover of a seed which protects the inner embryo.
Crustaceans
File:Crab from Long Island.jpg from Long Beach, New York]]
In crustaceans, the carapace functions as a protective cover over the cephalothorax (i.e., the fused head and thorax, as distinct from the abdomen behind). Where it projects forward beyond the eyes, this projection is called a rostrum. The carapace is calcified to varying degrees in different crustaceans.{{Cite web |editor-last=Pentcheff |editor-first=Dean |title=Carapace |url=http://atiniui.nhm.org/glossary/define.html?term=Carapace |access-date=17 June 2012 |website=Crustacea Glossary |publisher=Natural History Museum of Los Angeles County |archive-date=23 September 2013 |archive-url=https://web.archive.org/web/20130923035009/http://atiniui.nhm.org/glossary/define.html?term=Carapace |url-status=dead }}
Zooplankton within the phylum Crustacea also have a carapace. These include Cladocera, ostracods, and isopods, but isopods only have a developed "cephalic shield" carapace covering the head.
Arachnids
{{See also|Spider anatomy}}
File:Arachnid carapace.jpg, with the carapace highlighted in purple]]
In arachnids, the carapace is formed by the fusion of prosomal tergites into a single plate which carries the eyes, ocularium, ozopores (a pair of openings of the scent gland of Opiliones) and diverse phaneres.{{Cite book |last=Beccaloni |first=Jan |title=Arachnids |publisher=University of California Press |year=2009 |isbn=978-0-520-26140-2}}
In a few orders, such as Solifugae and Schizomida, the carapace may be subdivided. In Opiliones, some authors prefer to use the term carapace interchangeably with the term cephalothorax, which is incorrect usage, because carapace refers only to the dorsal part of the exoskeleton of the cephalothorax.
Alternative terms for the carapace of arachnids and their relatives, which avoids confusion with crustaceans, are prosomal dorsal shield and peltidium.
Turtles and tortoises
File:cmglee_Horniman_turtle_carapace_skeleton_bottom.jpg
{{Main|Turtle shell}}
The carapace is the dorsal (back) convex part of the shell structure of a turtle, consisting primarily of the animal's rib cage, dermal armor, and scutes.{{Cite book |last=Romer |first=A. S. |title=Osteology of the Reptiles |publisher=University of Chicago Press |year=1956 |author-link=Alfred Romer}}{{Cite book |last=Zangerl |first=R. |title=Biology of the Reptilia |publisher=Academic Press |year=1969 |editor-last=Gans |editor-first=C. |volume=1 |location=London |pages=311–340 |chapter=The turtle shell |editor-last2=Bellairs |editor-first2=D. d'A. |editor-last3=Parsons |editor-first3=T. A.}}
See also
References
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