What are gills?

Gills are a type of respiratory organ found in many aquatic animals.

They are also found in some of the worms, mollusks and crustaceans, insect larvae, all fishes, and a few amphibians.

Gills are composed of branched or feathery tissues rich in blood vessels, to facilitate the exchange of respiratory gases such as oxygen and carbon dioxide with the surrounding water. Gills may be enclosed in cavities or may project from the body into the water.