Quick Definition
The L-shaped bone forming the anterior and ventral borders of the opercular series, often bearing spines used in identification.
📖 Full Definition
The preopercle is the foremost bone of the opercular series, forming an L-shape with its vertical limb running parallel to the back edge of the cheek and its horizontal limb extending along the lower jaw. Its posterior edge may be smooth or armed with spines or serrations, which are important taxonomic characters. Many groupers, basses, and wrasses bear characteristic preopercular spines.