What is gills?

Gills are specialized structures found in aquatic animals such as fish, crustaceans, and some mollusks. They are used for respiration, which involves extracting oxygen from water and releasing carbon dioxide.

Gills consist of a series of thin, flat, and highly vascularized structures that are covered with tiny filaments or lamellae. The filaments provide a large surface area, which maximizes the exchange of gases between the water and the animal's blood.

Water flows over the gills and oxygen diffuses across the thin membranes of the gill filaments into the animal's bloodstream, while carbon dioxide diffuses out from the blood into the water. The movement of water over the gills is often facilitated by the animal's movements or specialized structures such as gill covers (opercula) in fish.

In addition to respiration, gills may also be involved in other functions, such as regulating salt and water balance, excreting waste products, and sensing the environment. Nevertheless, gills are critical adaptations that allow aquatic animals to survive in their unique environment.