For centuries, narwhal tusks have been expensive luxury items. Viking traders marketed the tusks as unicorn horns to Europeans during the Middle Ages. Now, only indigenous groups, such as the Inuit, can legally hunt the whales. But laws don't stop poachers. Two Tennessee men recently pleaded guilty to trafficking more than 100 narwhal tusks worth between $1.5 and 2.1 million, according to the U.S. Department of Justice.The high-priced tusk is actually the narwhal's left canine. Normally, only males grow this tooth, which can reach 8 feet long or more. Narwhals use their nerve-filled tusks as a sensory organ and to communicate. Along with poachers, climate change threatens the whales because the animals depend on thick pack ice in the Atlantic Arctic. The International Union for the Conservation of Nature (IUCN) classifies the narwhal as “Near Threatened.”(news.discovery.com)ANN.Az