Argulus and trichodina are both common parasites found on these organs, while in insects, the plastron can often act as a certain type of one. They are protected by bony plates called the opercula while the rakers of this organ are used to filter out food. In vertebrae they are located on the exterior of the pharynx and play a key role in maintaining tonicity with the surrounding environment. Oxygen diffuses through these organs, while nitrogen and carbon dioxide are expelled through them. Lampreys have seven of them while most sharks have five of these. FTP, identify 
Argulus and trichodina are both common parasites found on these organs, while in insects, the plastron can often act as a certain type of one. They are protected by bony plates called the opercula while the rakers of this organ are used to filter out food. In vertebrae they are located on the exterior of the pharynx and play a key role in maintaining tonicity with the surrounding environment. Oxygen diffuses through these organs, while nitrogen and carbon dioxide are expelled through them. Lampreys have seven of them while most sharks have five of these. FTP, identify this common respiratory organ found in aquatic organisms.
Argulus and trichodina are both common parasites found on these organs, while in insects, the plastron can often act as a certain type of one.
Gills 