What is the scientific name for the narwhal?

The scientific name for the narwhal is Monodon monoceros. It is the only living species in the genus Monodon and one of just two living members of the family Monodontidae, the other being the beluga whale.

Carl Linnaeus formally described the narwhal in 1758. The name combines Greek roots meaning “single tooth” and “single horn,” referring to the long, spiral tusk most commonly seen in males. That tusk is actually a greatly elongated left canine tooth, not a horn.

Narwhals are Arctic toothed whales with a rounded forehead, no true dorsal fin, and a thick layer of blubber for cold water. Their closest living relative is the beluga, and the two species can occasionally interbreed. The names in the wrong options belong to other cetaceans: Balaenoptera musculus is the blue whale, Orcinus orca is the killer whale, and Delphinapterus leucas is the beluga.