How do narwhals survive?

Narwhals stay alive by fearsome appearance, camouflaged coloring, and behavioral adaptation. For example, the males have a frontwards projecting tusk that's one-third to one-half the length of the rest of the body. Both female and male narwhals have protective coloring that apes the play of light and shadow in the Arctic waters. And narwhals relocate with the seasonal supply of food. In the summer, they feed off shallower waters. In the winter, they migrate to deeper waters where they perform among the deepest known mammalian dives. Additionally, they're helped by regulations on their hunt. Their main predators are indeed hunters: humans, killer whales [Orcinus orca], and polar bears [Ursus maritimus].