The Narwhal (Monodon monoceros) or narwhale is a species of whale native to the Arctic Ocean off the coasts of Greenland, Canada, and Russia. They are the only living whales to possess a spiraling tusk. This tusk can grow to be 10 feet long and grows from the left side of their jaw. Only the males possess this unique tooth. Some males are born without a tusk, making it hard to distinguish it from the females. About 1 in 500 male narwhals will have two tusks, the second tusk growing from the right side of their jaw.
Scientists haven't came to a conclusion as to what this tusk is mainly used for, but it likely serves several different purposes. It was long believed that male narhwals would use their tusks to fight other males, similar to the way male deer use their antlers. The tusk also shows females that they are healthy and strong. They could also be used as ice picks to break ice on the water's surface so they can breath. The tusks also have nerve systems that are extremely sensitive to changes in their oceanic environment. These tusks can even be used to project echolocations and tap fish to stun them. Scientists once thought that these tusks would serve good defense from predators like orcas and polar bears. But recent footage of orcas and polar bears predating upon narwhals has shown to be fairly easy.