The most distinctive feature of the narwhal is its long helical tusk. Present only in males, this tusk is an elongated canine tooth that grows in a left-handed spiral pattern. It can reach lengths of up to 10 feet and weigh several pounds. While the tusk's primary function is thought to be for attracting females during mating season, it is also used for social displays, self-defense, and possibly for breaking ice to access breathing holes.