The Narwhal is a mysterious creature of the high Arctic that has been the inspiration for tales of unicorns. David Attenborough looks at how the striking appearance of the spiral tooth inspired art. The reason why it has only one tusk and why it is spiral is still something of a conundrum. Two-tusked narwhals are occasionally discovered giving us insight into its evolutionary past. Elizabeth I was said to have paid tens of thousands of pounds to own a narwhal tusk. In the last ten years a team of scientists have been taking a close-up look at the tusk to find out what it might be used for. One of the latest theories comes after scanning microscopy revealed densely packed nerve cells within the tusk-perhaps the tusk is more of a sensory tool than a joust for fighting.

Encoded with permission for digital streaming by Infobase on November 24, 2014. Learn360 is distributed by Infobase for Films for the Humanities & Sciences, Cambridge Educational, Meridian Education, and Shopware.

The Narwhal and the Unicorn Myth(3:32) -- Purpose of the Narwhal's Tusk (3:12) -- Sensory Tool? (3:48) -- The Successful Spiral of Snail Shells (2:23) -- The Nautiloids (2:31) -- Spiraled Shells (3:14) -- Benefits of the Asymmetrical Shell (1:43) -- Credits: The Narwhal's Tusk: Attenborough's Natural Curiosities, Series 1 (0:45).