Original text - Engels - Although many aquatic insects live underwater,...

Although many aquatic insects live underwater, they get air straight from the surface through hollow breathing tubes (sometimes called siphons) that work on the same principle as a diver's snorkel. In mosquito larvae, for example, the siphon tube is an extension of the posterior spiracles.

Many aquatic plants maintain their bouyancy by storing oxygen (a waste product of photosynthesis) in special vacuoles.