A Curious Twist (S01E04)

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. (Prime Video)