air bladder

The air bladder therefore assists the ear of the catfish as the tympanum and its bones assist the ear of the higher animals.

In the great majority of fishes, a curious sac or bag known as the swimming or air bladder is found.

Then also, this elaborate air-bladder communicates with the mouth and throat by a tube, which corresponds to a windpipe.

These fishes generally have an air-bladder, and the gills lie close together in a cavity covered by an operculum.

The dorsal and ventral fins are both very long; and, as is usual with bottom fishes, the swimming or air bladder is absent.