What is the maximum length of a narwhal's tusk?

The maximum length of a narwhal’s tusk is up to 3 meters. The tusk is actually an elongated upper-left canine tooth that grows in a distinctive spiral, usually in males. Most females lack a tusk, although some grow one, and rare males develop two.

Narwhals use their tusks primarily in social interactions and probably for displaying age, strength, or status. Earlier theories suggested the tusk was used to break ice or spear prey, but observations show narwhals generally feed on fish, squid, and shrimp by suction rather than impaling them. The tusk also contains millions of nerve endings, making it unusually sensitive to changes in the surrounding water.

A common mix-up is confusing a narwhal’s tusk with a horn. It is not a horn or an external weapon: it is a tooth projecting through the upper lip. The tusk’s spiral shape and extreme length make it one of the most recognizable anatomical features in the animal kingdom.