Gill slit

Gill slit

Gill slits are gills with individual openings rather than an outer cover. Cartilaginous fish such as sharks, rays, sawfish, and guitarfish all have gill slits. Most have five pairs, but a few species have 6 or 7 pairs. Bony fish have an outer bony gill covering called an operculum.

The term "gill slits" also refers to the folds of skin in all vertebrate embryos. The skin folds in mammals, birds, and reptiles are gill slits, but the gill slits in embryonic fish develop into gills, while the gill slits in other vertebrates develop into the throat area and the bones in the ear. Gill slits exist in all vertebrates at some time in their embryo stage. When the vertebrate reaches a certain point in its life the skin folds fuse together and the bones form the trachea and ear bones. Except in fish where they form the gills themselves.

In the 19th century, gill slits of vertebrate embryos were erroneously thought to be actual gills, and thus evidence for the recapitulation theory.


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  • Gill slit — Slit Slit, n. [AS. slite.] A long cut; a narrow opening; as, a slit in the ear. [1913 Webster] {Gill slit}. (Anat.) See {Gill opening}, under {Gill}. [1913 Webster] …   The Collaborative International Dictionary of English

  • Gill slit — Gill Gill (g[i^]l), n. [Dan. gi[ae]lle, gelle; akin to Sw. g[ a]l, Icel. gj[ o]lnar gills; cf. AS. geagl, geahl, jaw.] 1. (Anat.) An organ for aquatic respiration; a branchia. [1913 Webster] Fishes perform respiration under water by the gills.… …   The Collaborative International Dictionary of English

  • gill slit — n one of the openings or clefts between the gill arches in vertebrates that breathe by gills through which water taken in at the mouth passes to the exterior and bathes the gills also BRANCHIAL CLEFT * * * a long narrow opening from the pharynx… …   Medical dictionary

  • gill slit — [gil] n. any of a series of paired, slitlike openings between the pharynx and the area behind the mouth of fishes, some amphibians, etc …   English World dictionary

  • gill slit — noun one of a series of slit openings in the pharynxes of fishes and aquatic amphibians through which water passes • Syn: ↑branchial cleft, ↑gill cleft • Hypernyms: ↑structure, ↑anatomical structure, ↑complex body part, ↑bodily structure, ↑ …   Useful english dictionary

  • gill slit — gill opening …   Dictionary of ichthyology

  • gill slit — noun Date: 1854 1. any of the openings or clefts between the gill arches in vertebrates that breathe by gills through which water taken in at the mouth passes to the exterior and so bathes the gills 2. any of the rudimentary grooves in the neck… …   New Collegiate Dictionary

  • gill slit — /gil/. See branchial cleft. [1850 55] * * * …   Universalium

  • gill slit — noun An individual opening to gills, which lacks an operculum; characteristic of Cartilaginous fish such as sharks …   Wiktionary

  • gill cleft — gill slit …   Dictionary of ichthyology

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