A pod of male narwhals gather at the Arctic ice edge to eat cod in Lancaster Sound.

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Meet the Narwhal

If you wanted to find our unicorn of the sea, your best bet might be to start in the Arctic Ocean off Canada, perhaps in Baffin or Hudson Bay. If you struck out there, you could venture to Greenland or Svalbard. Narwhals navigate polynyas, which are pools of open water in otherwise iced-over environments. They're the arctic equivalent of an oasis. That's not the only reason polynyas are interesting -- they're biodiverse marine environments, rich in organisms like phytoplankton and copepods (little crustaceans) that serve as feeding grounds for birds, walruses and whales.

You could spot the male whale (and a few female whales) by its long, spiral tusk, but what else could you look for? Besides "unicorn of the sea," the narwhal is known by another name: corpse whale. An adult narwhal has a mottled dark gray or black and white color, and some morbid observer must have decided that the patchy discoloration resembled livor mortis, what happens to a body after death when blood settles underneath the skin. If you see a little gray narwhal with no white patches, that's a baby, whereas a completely white narwhal is probably an old whale.

From top to bottom: humpback whale, killer whale, Pacific white-sided dolphin, beluga, narwhal and Ganges River dolphin.

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Still not sure it's a narwhal? Don't look for a dorsal fin, because it only has a dorsal ridge, which makes it easier to swim under ice. Narwhals travel in groups -- usually 20 or 30 at a time, although during migration, you might see thousands of them together. A female narwhal weighs in at around 2,200 pounds (998 kg), with males at 3,500 pounds (1,588 kg). An adult female will be about 13 feet (400 cm) long, a male about 15 feet (457 cm).

Your­ tip-off that's it a narwhal and not a beluga? The tusk, which is usually covered in algae. The scientific name for the narwhal is Monodon monoceros, but it's completely wrong. It means "one tooth, one horn," but the narwhal actually has zero horns and two teeth -- that tusk is a tooth that's simply grown upwards and pierced the lip. (We'll talk more about this truly amazing tooth in another section.)

If you wanted to take your new pal out to lunch, HowStuffWorks recommends the fish you can find in cold waters -- cod, salmon, herring and halibut. Narwhals also like a good shrimp or squid feast. But if you're trying to make a reservation, you're out of luck -- no one is sure just how many narwhals there are. In parts of Baffin Bay, where narwhals are most populous, the number has been recorded at 34,000 [source: Culik]. And you won't be able to tell if the narwhals really enjoyed your company -- like dolphins, they have permasmiles.

We're still in the getting-to-know-you phase with narwhals. How old do they get? One study on narwhal eyes put the oldest subject at 115 years [source: Garde et al.]. Is that unusual? We don't know. Why do they have that tusk? We're not positive, but we have some ideas. Why do they dive so deeply? Let's take a look at narwhal behavior.

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