The ear's the organ that detects sound. The vertebrate ear shows a common biology from fish to humans, with variations in structure according to order and species. It not only acts as a receiver for sound, but plays a major role in the sense of balance and body position. The ear's part of the auditory system. The word "ear" may be used correctly to describe the entire organ or just the visible portion. In most animals, the visible ear's a flap of tissue that's also called the pinna. The pinna… (More on Ear)