opercle

[ oh-per-kuh l ]

/ ˈoʊ pər kəl /

an operculum, especially the posterior bone of the operculum of a fish.

Origin of opercle

First recorded in 1590–1600, opercle is from the Latin word operculum cover. See operculum, -cle²

On our sunfish we see that the opercle ends behind in a long and narrow flap, which looks like an ear.

A Guide to the Study of Fishes, Volume 1 (of 2) |David Starr Jordan
Overlying these is the system of membrane bones already mentioned, including the opercle or gill-cover.

Elementary Zoology, Second Edition |Vernon L. Kellogg
In most of the higher fishes a small accessory gill (pseudobranchia) is developed in the skin of the inner side of the opercle.

A Guide to the Study of Fishes, Volume 1 (of 2) |David Starr Jordan
The largest uppermost flat bone of the gill-covers is known as the opercle .

A Guide to the Study of Fishes, Volume 1 (of 2) |David Starr Jordan

In Erpetoichthys only the opercle is distinct among the gill-covers.

A Guide to the Study of Fishes, Volume 1 (of 2) |David Starr Jordan