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单词 exoskeleton
释义
exoskeleton

Biology
  • A rigid external covering for the body in certain animals, such as the hard chitinous cuticle of arthropods. An exoskeleton protects and supports the body and provides points of attachment for muscles. The cuticle of arthropods must be shed at intervals to allow growth to occur (see ecdysis). Other examples of exoskeletons are the shells of molluscs and the bony plates of tortoises and armadillos. Compare endoskeleton.


Geology and Earth Sciences
  • A general term applied to the hard covering of many invertebrates. It may be a shell growing at the edges only (by accretion) or a series of plates. The term is most commonly applied to the horny skeleton enclosing the body of all Arthropoda and secreted by the underlying cellular layer. The exoskeletal material (cuticle) is composed of a complex glycoprotein, is relatively impermeable to water, and has a high strength-to-weight ratio. It provides insertion sites for muscles (apodemes) and is divided into separate plates that facilitate movements. The plates are connected by thin, untanned cuticle. In trilobites (Trilobita) and crustaceans (Crustacea) the cuticle is impregnated with mineral salts (calcium carbonate and calcium phosphate) which give increased strength. The exoskeleton is moulted periodically (ecdysis) to permit body growth.


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