Narwhal whales live in the arctic regions of Russia, Greenland, Norway and Canada, along with two other whale species, the bowhead and beluga. Most narwhals winter under sea ice for up to five months.
Narwhals are equipped with one or two spiral tusks that protrude from the front of their heads. For this reason, they are nicknamed unicorns of the sea. The tusk is actually a large tooth that may grow to 10 feet; it contains approximately 10 million nerve endings. More than 80,000 narwhals populate the arctic. They reach lengths of 17 feet and weigh up to 4,200 pounds. Climate change and energy development are the largest threat to their existence, according to the World Wildlife Fund.