Narwhals lack a dorsal fin, possibly an evolutionary adaptation to help them swim under ice. Their neck vertebrae are jointed, like those of land mammals, rather than fused together as in most whales. Both of these features are shared by the beluga whale. Of course, the most striking feature is its long, pointed horn at the front of its face. This Narwhal measures 19 x 6.5 x 3 centimeters.