How does a pond snail obtain oxygen?

pulmonates or land snail have a space in the body known as the mantle cavity this area has many blood vessels is well supplied with blood vessels and acts as the animal's lung. land snails have a lung that works almost exactly the same way that our lungs do. The lung can be opened to the outside via a hole called a pneumostome on the right side of the snails body. Opening it to inhale or exhale and closing it to keep from drying out. Oxygen enters into the snails body from the air within the mantle cavity. Carbon dioxide diffuses from the blood into the mantle cavity, to be released when it exhales. Water snails have gills through which they can breathe. I think they get it from there things on top of there head!!!!