A whale (family Monodontidae) that has two teeth, one of which (almost always the left) is enlarged in the male into a spiral tusk up to 2.5 m long projecting through the lip; rarely do both teeth form tusks. Narwhals are white with dark mottling, about 4 m long, and have a high, rounded forehead, no dorsal fin, and short, rounded flippers. They occur in the Arctic Ocean.