Narwhal males use their tusk to hunt. As they hunt mostly Greenland halibut, one theory suggests they use these unique long tusks to find the fish that live mostly or entirely on the ocean's floor. It is known that tuskless and younger unicorns mostly depend on other preys found in the upper level of the water.
Some scientists also suggest that narwhal tusks are mostly an effective tool during winter as that's when these fish species move close to the surface. The ice sheet becomes compact during the extreme winter. Narwhal tusks enable them to break the ice and get food even when the entire Arctic Ocean freezes.
Competition and Dominance
Since most Narwhal males have tusks, their tusks are also important in competition for females and dominance over other individuals in the pod. The longer the narwhal's tusk, the better he is at protecting himself and his potential mate. When two narwhals meet or conflict with each other, they'll use their tusks to threaten each other.
However, it's rare to see narwhals stabbing or hitting one another with the tusks. When it does happen, it is more like fencing. Their horn is just a sign of power, strength, and dominance in any situation. In their habitat, no other predator dares to threaten an adult male narwhal, who wields these incredible tusks.
Sensing the Environment
The tusk of the narwhal is known to house various nerve endings. These nerve endings act like sensory receptors. They act like a built-in radar system that helps the narwhal feel and sense changes in the water that surrounds them.
Through these nerve endings, the narwhals can detect changes in temperature, pressure, and density of the water, which helps them hunt and navigate their environment. It even helps them detect any danger approaching them.
Courtship and display
The narwhal's tusk also plays a significant role during the courtship and display. During the mating season, the tusks become a sign of attraction. The male will present their impressive tusks toward the female; the bigger the tusk, the better the chances the male has of attracting the females.
As already mentioned, the narwhal's tusks are rich in nerve endings. Therefore, they are extremely sensitive. When the male narwhal is displaying courtship, they'll rub the female narwhal with the tusk to build their bond and trust.