DO WE KNOW ABOUT NARWHALS?
September 2, 2012
I recently saw an ABC News commentary where people were watching narwhals somewhere
in the Arctic. They have a long, pointed horn that looks like a spear. What exactly
are narwhals? What do ecologists know about these intriguing creatures?
Narwhals are a sort of marine unicorn of the Arctic Ocean. Males of the species
have a long, protruding tusk (up to 10 feet!) that develops from the single, left
upper jaw tooth. I have seen drawings of male narwhals engaged in what looked
like fighting, and some scientists have suggested the horns 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.
the case, since males have the tusks and females do not, they are presumably used
in some activity that males do different from the opposite sex. Mating with females
seems a likely guess. Perhaps they use them to intimidate other males or simply
to impress females. To my mind, narwhals are not as charming as their closest
relative, the beluga whale, but they come close.
to "Walker's Mammals of the World" by R. M. Nowak (1999, Johns Hopkins
University Press, Baltimore), which remains the best overall scientific authority
on mammals, belugas and narwhals are separate genera, each with a single species.
They are the only two species in a family of whales know as the Monodontidae,
which means "one tooth." The narwhal was described to science first,
in 1758 by Linnaeus, and the single tusk, a long, modified tooth, would clearly
have been the most noticeable feature, although narwhals typically have another,
smaller tooth as well.
beluga whales and narwhals inhabit some of the coldest waters on the planet and
migrate long distances. Narwhals have the most northerly geographic range of any
mammal, almost entirely above the Arctic Circle, and rarely travel farther south
than 70 degrees north latitude. One measure of the frigid conditions narwhals
live under is that one-third of their body weight is blubber, which serves as
an insulator and a source of energy. Despite the contention by some folks that
global warming is not really happening, if the ice cover maps I have seen are
any indication, 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 and feeding patterns. What the final outcome would be for
the species is uncertain.
restriction of narwhals to an ocean habitat in a climate that is almost uninhabitable
by humans is one reason for limited scientific knowledge of the behavior and mating
systems of these fascinating creatures. The knowledge that, on average, males
are more than 15 feet long (not counting the bayonet protruding from the head),
weigh over 3,500 pounds, and are larger than females has been determined from
specimens that were killed. Baby narwhals are born during summer and are already
five 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.
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, their
purpose is to feed on a variety of fish, squid, and crustaceans. Some narwhals
can remain underwater for more than 15 minutes but like other mammals must eventually
surface to breathe. The use of echolocation for navigation has not been verified
in the species, but they are known to make several noises--whistles, clicks, groans--that
could be used for orientation in the dark.
are cool animals indeed. In fact, they are arguably the coolest animals in the
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