ECOVIEWS: Mysterious narwhals are the unicorn of Arctic Ocean

As much as I applaud scientific research that reveals nature’s secrets, I feel a sense of satisfaction when some natural mysteries remain mysteries. The narwhal is my favorite example.

Narwhals are a sort of marine unicorn of the Arctic Ocean. Males have a long tusk (up to 10 feet!) that develops from the single, left upper jaw tooth. Some scientists have suggested the spears are used in male-male combat. I am not aware of any definitive study confirming that the tusks are used for fighting, rather than just for display. However, reports of tusk injuries to adult males suggest that combat may sometimes occur.

Whatever the case, males have tusks and females typically do not, so they are presumably used in some activity that males do differently from the opposite sex. Male combat or some aspect of mating seem likely guesses. Perhaps they use them to intimidate other males or simply to impress females. To my mind, narwhals are about as charming as their closest relative, the beluga whale. The two species belong to a family of whales known as the Monodontidae, which means “one tooth.” The narwhal was first described to science in 1758 by Linnaeus. The single tusk would clearly have been the most noticeable feature, although narwhals typically have another, smaller tooth.

Beluga whales and narwhals inhabit some of the coldest waters on the planet and some migrate long distances. Narwhals have the most northerly geographic range of any mammal, almost entirely above the Arctic Circle, the northern region where the sun does not appear on Dec. 21 and does not set on June 21. One-third of a narwhal’s body weight is blubber, which serves as an insulator and a source of energy.

The restriction of narwhals to an ocean habitat in a climate that is almost uninhabitable by humans is one reason for the limited scientific knowledge regarding behavior and mating systems of these fascinating creatures. The knowledge that males can reach 15 feet in length (not counting the bayonet protruding from the head), can weigh over 3,500 pounds and are larger than females has been determined from dead specimens. Born in summer, newborn narwhals are already 5 feet long and weigh 175 pounds. Not surprisingly, a mother narwhal, which averages less than a ton, produces a single offspring at a time. The gestation period is more than 15 months. Mother narwhals are thankful their sons do not develop bayonets until after they are born.

As if the surface in the Arctic seas isn’t cold enough for narwhals, radiotelemetry studies have revealed that narwhals commonly dive to ocean depths of more than 800 feet. Aside from the sheer fun of swimming in ice cold ink-black water, they dive to feed on a variety of fish, squid and crustaceans. Narwhals have been known to remain underwater for more than 15 minutes, but like any mammal they must eventually surface to breathe. They make several noises -- whistles, clicks, groans — like other whales that use echolocation for communicating in the dark.

Despite the contention by some folks that global warming is a hoax, the character of the Arctic habitat where narwhals live is changing dramatically. Diminishing ice and seasonal temperature changes could have an impact on narwhal migration, feeding patterns and body temperature regulation. A continuing threat to some narwhal populations comes from commercial overharvesting. What the ultimate fate of the species will be is uncertain.

Conducting research in the narwhal’s dark, freezing habitat is difficult. Nonetheless, scientists have learned an extraordinary amount about the ecology and behavior of these intriguing animals. However, biological mysteries remain, not the least being, to what purpose or purposes do the males put those enormous spears? Narwhals are cool animals indeed. In fact they and beluga whales are the coolest mammals on the planet. Literally.

Whit Gibbons is professor of zoology and senior biologist at the University of Georgia’s Savannah River Ecology Laboratory. If you have an environmental question or comment, e-mail ecoviews@srel.edu.