Glossary

opercle

Bone forming the upper, posterior portion of the operculum, sometimes bearing spines or spine-like structures. Normally the largest of the bones comprising the operculum.

Used in 150 species profiles

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Related terms

branchiostegal membrane
The membrane, sometimes referred to as the gill membrane, connecting the branchiostegal rays and enclosing the ventral portion of the branchial cavity. Normally extended when the opercle of a fish is open, sealing the branchial cavity and creating a vacuum in the mouth, and also used during threat, courtship and other communicative behaviours in many species.
humeral spot
A marking on the body in the area analogous to the humerus, or shoulder. In fishes it's normally located above the pectoral-fin and behind the opercle. There may be more than a single such spot in some species.
operculum
Flap composed of 4 bones that covers, supports and protects the gill opening in many fishes. Also known as gill flap or gill cover.
pectoral-fin
Anterior, paired fin attached to the pectoral girdle of fishes, usually just behind the opercle and corresponding to the forelimbs of higher vertebrates. Assists in controlling direction of movement and swimming speed. Frequently abbreviated to 'P' or 'P1' in scientific papers.
posterior
Located near or towards the rear end; further back in position.
preopercle
Bone forming the posterior and lower margins of the cheek; the anteriormost bone of the opercle. Also known as the preoperculum.
pseudotympanum
Translucent, triangular area in the humeral region, behind the opercle, without muscle and where the anterior part of the gas bladder is in direct contact with the skin. It is hypothesised to function as a hearing aid in many juvenile characoids and is present in adults of certain species, notably members of the family Cheirodontidae.
subopercle
One of the bones comprising the operculum, situated below the opercle.

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