The Probert Encyclopaedia of Nature

GILLS

Gills are the respiratory organs of aquatic animals. They are specialized thin-walled regions of the body surface through which dissolved oxygen is taken into the blood and carbon dioxide released into the water. The gills of fish lie in gill slits on each side of the gullet. The gills of molluscs and fanworms have hair-like cilia that trap food particles in the water flowing over the gills. The external gills of amphibian larvae are feathery structures projecting from the body wall.
Research Gills