Wildlife
Climatology
The Expedition
Peoples Of The North
The Global Issues
The "Making Of"
A sword that defies the imagination -- the narwhal tusk
Caroline Underwood Writes from Pond Inlet, Baffin Island
The Bowhead Whale, Balaena Mysticetus
PLANKTON: The Oceans’ Most Abundant Food Source
Is the polar bear a marine mammal or a land mammal?
Thick-Billed Murre, Uria lomvia
Will Commercial Whaling Resume Again?
A Sword That Defies The Imagination -- The narwhal Tusk
by
Isabelle Deslandes, Ship's doctor
There is a mysterious whale that inhabits our Arctic sea – an extraordinary creature that could be mistaken for an aquatic version of the mythical unicorn. It is the narwhal.
What makes the narwhal so special? Its tusk.
The narwhal’s ivory tusk is hollow, slender and usually spirals in
a counter-clockwise direction. This tusk is actually the gigantic extension
of a transformed left upper canine that grows through the jaw. It can grow
to 2 or 3 metres long and can weigh up to 10 kilograms. A single tusk is typically
seen in adult males and continues to elongate during its lifetime. Some animals
have been observed with two tusks, one on the right side, one on the left,
but these are uncommon occurrences. In rare cases, some females have been
observed with smaller, denser, horn-like structures in lieu of the tusk of
the male.
Thirteen
Northern Native communities are permitted to hunt the narwhal. The ivory harvested
from the tusks represents a profitable export. Prices for one tusk can reach
$3,000 US! (Such high prices can be fetched in Japan, where the ivory is believed
to have aphrodisiac properties.) Tusks are also carved by local sculptors.
But what do the narwhal whales use their tusks for?
Several hypotheses have been offered to explain the purpose of this intriguing structure. The first hypothesis was that the narwhal useds the tusk as a sword to harpoon pelagic fish. An attractive idea until one poses the question, then how does the whale eat the fish attached to the tip of its tusk? The second hypothesis was that the tusks are used to scratch the ocean floor to harvest bottom-dwelling organisms. Another idea, which pleased quite an audience at the time, was that the tusk function as an ear. The single hypothesis currently accepted by scientists is that the tusk represents a secondary sexual characteristic used by males to indicate social ranking. Males use their tusks in non-aggressive encounters between each other by crossing them repetitively in unique patterns. It is suggested that this behaviour attracts receptive females during mating season.
