The specialized anatomy of the dolphin ear probably allows it to localize sounds under water effectively, a task that is difficult for humans. When a dolphin dives, this tissue helps adjust pressure on the middle ear. A dolphin has small external ear openings, a few inches behind each eye. Each opening leads to a reduced ear canal and an eardrum. Some scientists believe that dolphins receive sound through these openings.
Dolphins have acute vision both in and out of the water.
A dolphin's eye is particularly adapted for seeing in water. In air, certain features of the lens and cornea correct for the refraction of light caused by the transition from aquatic to aerial vision. A dolphin's retinas contain both rod cells and cone cells, indicating that they may have the ability to see in both dim and bright light. The presence of cone cells suggests that dolphins may be able to see color, although studies on bottlenose dolphins haven't documented color vision. Anatomical studies and observations of behavior indicate that a bottlenose dolphin's sense of touch is well developed.