Operculum (fish) required, such as ventilation.. Operculum (fish) The operculum is a series of bones found in bony fish that serves as a facial support structure and a protective covering for the gills; it is also used for respiration and feeding. The opercular series contains four bone segments known as the preoperculum, suboperculum, interoperculum and operculum. The preoperculum is a crescent-shaped structure that has a series of ridges directed posterodorsally to the organisms canal pores. The preoperculum can be located through an exposed condyle that is present immediately under its ventral margin; it also borders the operculum, suboperculum, and interoperculum posteriorly. The
Blob sculpin flap that covers the gills), the branchiostegal membranes are fused to the isthmus (the fleshy projection separating the gill openings), and there are many small cirri (fleshy threads) scattered over the head and body. The operculum is poorly ossified and is covered by a gelatinous layer. Behind the head, the body tapers rapidly to the caudal peduncle and there is a gelatinous layer between the skin and the muscle. The dorsal fin has eight spines and nineteen to twenty soft rays, and the anal fin has no spines and twelve to fourteen soft rays. The pectoral fins are broad and