spiracle defined in 1951 yearspiracle - spiracle;
spiracle - (1) Dorsally situated reduced first (most anterior) gill-slit in many fish. Its small size results from the connection formed between mandibular and hyoid arches for firm attachment of jaws; between these arches the spiracle lies. See also: Visceral Arch, Hyostylw Jaw Suspension. In most living bony fish, spiracle is closed up. The gill-pouch of embryo tetrapods representing spiracle develops into cavity of middle ear and Eustachian tube. (2) Of insects, synonym of stigma; external opening of trachea.
near spiracle in Knolik
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