Title: How Narwhals Work | HowStuffWorks
Headings: How Narwhals Work
How Narwhals Work
Meet the Narwhal
Narwhal Behavior
The Narwhal Tusk
Threats to Narwhals
Citation

Content: And now let's look at the narwhal's distinguishing feature: its tusk. Advertisement
The Narwhal Tusk
Closer look at the narwhal tusk
Paul Nicklen/National Geographic/ Getty Images
The narwhal's tusk isn't unique at first glance. Elephants, rhinos and walruses all have these long, protruding teeth. But this one is different from any other tooth you've ever seen. Contemplate your own teeth for a second. We usually only think about them when there's something wrong -- a chip, a cavity, discoloration. But teeth themselves are incredibly durable, able to survive fire and outlast the rest of your body after death. Teeth are hard, which makes them useful for their main purpose in humans: chewing food.