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The molted carapace of a lady crab 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 decapod (crustaceans, such as a crab, lobster, shrimp or prawn) is made up of 20 body segments grouped into two main body parts: the cephalothorax and the pleon . [1] [2] Each segment may possess one pair of appendages, although in various groups these may be reduced or missing. They are, from head to tail:
Carapace: A hardened plate (sclerite) covering the upper (dorsal) portion of the cephalothorax; [3] see also Carapace; Carpoblem: The principal tibial apophysis on the male pedipalp; also just called the tibial apophysis; Cephalic region or caput: The front part of the cephalothorax, separated from the thoracic region by the cervical groove [4]
Spiders, unlike insects, have only two main body parts instead of three: a fused head and thorax (called a cephalothorax or prosoma) and an abdomen (also called an opisthosoma). The exception to this rule are the assassin spiders in the family Archaeidae, whose cephalothorax is divided into two parts by an elongated "neck". In the majority of ...
In spiders, the cephalothorax and abdomen are joined by a small, cylindrical pedicel, which enables the abdomen to move independently when producing silk. The upper surface of the cephalothorax is covered by a single, convex carapace, while the underside is covered by two rather flat plates. The abdomen is soft and egg-shaped.
Horseshoe crabs are chelicerates, meaning their bodies are composed of two main parts : the cephalothorax and the opisthosoma. The first tagma, the cephalothorax or prosoma, is a fusion of the head and thorax. [25]: 555 This tagma is also covered by a large, semicircular, carapace that acts like a shield around the animal's body. It is shaped ...
In chelicerates and crustaceans, the cephalothorax is derived from the fusion of the cephalon and the thorax, and is usually covered by a single unsegmented carapace.In relation with the arthropod head problem, phylogeny studies show that members of the Malacostraca class of crustaceans have five segments in the cephalon, when not fused with the thorax to form a cephalothorax.
The head and thorax may be fused together to form a cephalothorax, [8] which may be covered by a single large carapace. [9] The crustacean body is protected by the hard exoskeleton, which must be moulted for the animal to grow. The shell around each somite can be divided into a dorsal tergum, ventral sternum and a lateral pleuron. Various parts ...