gill-plate

Each gill-plate is a tiny sac, and within these are the fine branches of the air-tubes.

Little Busybodies The Life of Crickets, Ants, Bees, Beetles, and Other Busybodies Julia Moody 1919

The wing of the May-fly flapping in the air is a respiratory organ, of as much importance to the wellbeing of the creature in its way, as the gill-plate of its grub prototype is when vibrating under the water.

Chambers's Edinburgh Journal, No. 437 Volume 17, New Series, May 15, 1852 Various 1836

A gill-plate grab is the easiest way and will keep your fingers away from the fish’s sharp teeth: (1) Curl all four fingers of your right hand into a U shape, then slip them under the fish’s right-side gill plate.

The Gill-Plate Grab: Catch & Release Pike Without a Net 2010