A dolphin breathes through a blowhole, a nostril on top of its head. The animal seals its blowhole by means of powerful muscles most of the time while underwater. Dolphins have a highly developed sense of hearing. Dolphins also have good vision, and the entire surface of their bodies has a keen sense of touch. All these senses function well both above and below the surface of the water.
Dolphins have no sense of smell.
Dolphins have a natural sonar system called echolocation, which helps them locate underwater objects in their path. A dolphin locates such objects by making a series of clicking sounds. These sounds leave the animal's body through the melon, an organ on top of the head. The melon consists of special fatty tissue that directs the sounds forward. Echoes are produced when the sounds reflect from an object in front of the dolphin.