spiracle

noun

A respiratory opening between the eye and the first gill slit of in Elasmobranchii, Acipenseridae, Polyodontidae, and Polypteridae; connects with the gill cavity, often retains branchial lamellae which are called the spiracular pseudobranch. Shark spiracles are small (e.g. Galeocerdo), but ray spiracles are larger and serve as an opening for water entering the gill chamber.