Long, white tusks break the surface of the icy Arctic water. Is it a waterlogged herd of unicorns? No, a pod of narwhals!
This species of whale is best known for its tusk - a long, spiraled tooth that usually only the males develop. (Females occasionally do.) The tusk can grow to 10 long and weigh more than 22 pounds.

Scientists do not know exactly why narwhals have tusks, though they might be used to impress females or fight other males. But tusks are more than battle swords. they're packed with nerves and covered in tiny holes that allow seawater to enter. This gives tusks a sensitivity that could help narwhals detect changes in their environment such as temperature or even the water's saltiness. Clues like these might help narwhals find prey or survive in other ways.

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