gill slit
Noun
Meaning
one of a series of slit openings in the pharynxes of fishes and aquatic amphibians through which water passes
Source: WordNetSynonyms
Hypernyms
Examples
Chimaeras differ from other cartilagenous fish, having lost both the spiracle and the fifth gill slit.
Cod have a distinct white lateral line running from the gill slit above the pectoral fin, to the base of the caudal or tail fin.