Spiracle
A small opening behind the eye of rays, skates and many sharks that lets them draw in water while resting on the bottom.
A spiracle is a small hole behind each eye, a leftover of a gill opening. Rays and skates, which lie flat on sand or mud, take in water through their spiracles rather than their mouths, so they do not suck sand into their gills. Many bottom-dwelling sharks, such as angel sharks and wobbegongs, have large spiracles too, while fast open-sea sharks have small ones or none. Bichirs, among bony fish, also have spiracles and can gulp air through them.