Narwhal << NAHR hwuhl >> is an Arctic whale known for its unusual tusk. The male has a spiral ivory tusk typically about 8 feet (2.4 meters) long that juts out of the left side of the upper jaw. The tusk is actually a tooth. Some males have two tusks. Most females have none. Narwhals may reach 15 feet (4.6 meters) long, not including the tusk, and can weigh 3.5 tons (3.2 metric tons). Adults are gray or white on top and whitish underneath. They are covered in dark spots. Newborns are typically gray.
People have long been intrigued by narwhal tusks, once selling them as unicorn horns. Scientists have proposed many explanations for the tusk’s purpose. Most scientists think the tusk plays a role in selecting mates. Research also indicates that the tusk is a sensory organ, detecting water temperature, pressure, and other sensations. Tiny tubes connect millions of nerve endings inside the tusk to the water outside.
