Narwhals are toothed whales, most closely related to the white whale or beluga, often seen in aquariums around the world. Males have a massive ivory tusk that is unique in the animal kingdom. This tusk typically grows from the left side of their upper jaw in a leftward spiral and can reach a length of up to three meters, while the narwhal itself is no more than five meters long.

Fossils of narwhals are very rare. From the Ice Age, a tooth fragment was found on the Taimyr Peninsula in the far north of Siberia. Fossils of the narwhal are also known from the British Isles. Narwhals still inhabit the Arctic and sub-Arctic regions today. They are often observed in the eastern Canadian Arctic and western Greenland.