The name "Narwhal" is based on the old Norse word, "Nar" meaning corpse. RUN!!! ZOMBIE NARWHAL! Oh, wait, it's because of their coloration, dur. Some people refer to them as "Moon Whales", and the Inuit, yeah those crazy guys! They call them " Qilalugaq", once again, with enough booze, you can make up anything. While the Inuit are allowed to hunt them, because they live in an ice house and all, and I guess they are still mad about that whole harpoon/ woman / beluga whale thing. Now, how the Inuit knew they were in the same family is a mystery, because they were always too drunk, I suppose. Don't tell Ahab, but they are both white whales!
The truth of the tusks origin gradually came out of the dark during the age of exploration. i guess they got fed up drinking out of "unicorn cups" and wanted to see what all the fuss was about. So explorers and naturalists started to go check them out for themselves.
And in 1555 some guy named Olaus Mangus published a drawing of a fish-like creature with a horn on its head. I guess he couldn't tell the difference between a whale and a fish, maybe it was the giant horn that threw him off?