The narwhal of arctic waters, a whale that grows up to twenty feet long and has
an eight-foot-long tusk, takes its name from the Scandinavian nar, “ghost” or
“corpse” (for its white color) and the Scandinavian word for whale. The narwhal
is probably responsible for the legend of the unicorn so widely believed in
medieval times. This “unicorn of the sea” uses its long tusk, or left incisor
tooth, which grows outward in a counterclockwise spiral, to battle other
narwhals. Only the male of the species has the tusk, employing it during the
mating season when fighting over females.