Decapod anatomy 1647005 215959239 2008-05-30T13:16:12Z Firefoxman 143982 Reverted edits by [[Special:Contributions/198.108.183.7|198.108.183.7]] ([[User talk:198.108.183.7|talk]]) to last version by Excirial [[Image:Penaeus_diagram_antennae.png|right|thumb|200px|Antennules]] [[Image:Penaeus_diagram_pereiopods.png|right|thumb|200px|Pereiopods]] [[Image:Penaeus_diagram_carapace.png|right|thumb|200px|Carapace]] [[Image:Penaeus_diagram_pleopods.png|right|thumb|200px|Pleopods]] [[Image:Penaeus_diagram_uropod.png|right|thumb|200px|Uropods]] [[Image:Penaeus_diagram_telson.png|right|thumb|200px|Telson]] The [[Decapoda|decapod]] [[crustacea]]n, such as a crab, lobster, shrimp or prawn, is made up of nineteen [[body segment]]s grouped into two main body parts, the [[cephalothorax]] and the [[abdomen]]. Each segment may possess one pair of [[appendage]]s, although in various groups these may be reduced or missing. They are, from head to tail: ==Cephalothorax== ===Head=== #antennules #[[antenna (biology)|antennae]] #[[mandible (arthropod)#Crustaceans|mandibles]] #[[Maxilla (arthropod)|first maxillae]] #[[Maxilla (arthropod)|second maxillae]] The head also bears the (usually stalked) [[compound eye]]s. ===Thorax / Pereon=== #first maxillipeds #second maxillipeds #third maxillipeds #first pereiopods #second pereiopods #third pereiopods #fourth pereiopods #fifth pereiopods '''Maxillipeds''' are appendages modified to function as mouthparts. Particularly in the less advanced decapods, these can be very similar to the pereiopods. '''Pereiopods''' are primarily walking [[arthropod leg|legs]] and are also used for gathering food. Those pereiopods which are armed with a claw (''chela'') are sometimes referred to as '''chelipeds'''. The pereiopods bear the sexual organs, which are the third pereiopod in the female and the fifth pereiopod in the male. Each appendage from the second maxilla to the fifth pereiopod also bears a [[gill]]. In the [[Anomura]] ([[hermit crab]]s and related animals), the fifth pair of pereiopods is often hidden inside the branchial chamber, where they are used to clean the gills. The cephalothorax is covered by a [[carapace]] which protects the internal organs and the [[gill]]s; the section of the carapace that projects in front of the eyes is called the '''rostrum'''. ==Abdomen / Pleon==<!-- This section is linked from [[Swimmeret]] --> #first pleopods #second pleopods #third pleopods #fourth pleopods #fifth pleopods #uropods '''Pleopods''' (also called ''swimmerets'') are primarily swimming legs, and are also used for brooding the eggs (except in [[prawn]]s), catching food (then swept to the mouth), and can sometimes bear their own gills. In some taxa, the first one or two pairs of pleopods are specialised in the males for fertilisation, and are referred to as the '''gonopods'''. At the end of the pleon is the '''tail fan''', comprising a pair of [[biramous]] '''uropods''' and the [[telson]], which bears the anus. Together, they are used for steering while swimming, and in the [[caridoid escape reaction]]. In [[crab]]s and some other [[carcinization|carcinised]] decapods, the abdomen is folded under the cephalothorax. <br clear="all"> [[Image:Krillanatomykils.jpg|left|thumb|300px|The anatomy of krill, using ''[[Euphausia superba]]'' as a model.]] [[Image:Pleopods_euphausia_superba.jpg|right|thumb|300px|The pleopods of ''[[Euphausia superba]]''.]] [[Category:Arthropod anatomy]] [[Category:Decapods]] [[fr:Anatomie des décapodes]] [[nl:Pleopode]] [[pt:Pleópode]]