Dictionary of Ichthyology  

 

gill opening = an external opening leading from the gill chamber. Also called gill slit or branchial opening. Elasmobranchii have 5-7 openings or slits on each side of the head while bony fishes have only one. The opening allows water to exit after passing over the gills for respiration.

From Kingsley's "Textbook of Vertebrate Zoology, 1906. A = elasmobranch, B = teleost.  Photograph by Brian W. Coad....more

Canadian Museum of Nature
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