Blowhole (anatomy)

Blowhole (anatomy)

In biology, a blowhole is the hole at the top of a cetacean's head through which the animal breathes air. It is homologous with the nostril of other mammals. As whales reach the water surface to breathe, they will forcefully expel air through the blowhole. Not only is air expelled, but mucus and nitrogen from the animal's metabolism, which has been stored in the whale while diving. The exhalation is released into the comparably lower-pressure, colder atmosphere, and any water vapor condenses. This spray, known as the blow, is often visible from far away as a white splash, which can also be partially caused by water resting on top of the blowhole.