Saturday, March 19, 2011

Strangest Tooth in Nature

I suppose I should answer the first question people have about this blog:  What’s the title mean?
As most people know, one of the most amazing things about the narwhal -- and its most notable physiological feature -- is that it has a tusk.  A spiral tusk that can extend up to eight feet long.  And that tusk is a tooth, one of only two teeth in its jaw.
The left tooth erupts through its upper lip and becomes its tusk while the right tooth remains impacted in its jaw and only rarely does it grow.  One narwhal researcher called the tusk “the most unusual tooth in nature” and perhaps the only example of asymmetry in teeth in the mammalian world.  (I should note that except in rare cases, only males have a tusk, and a very tiny percentage of males have two tusks.)
Perhaps equally bizarre is that fetal narwhals show evidence of four teeth – two in front and two in back – but by the time they are born, the two original back teeth have disappeared and the two front teeth have migrated to the back.  Why it would do that is anybody’s guess.  The narwhal’s tusk is also remarkably flexible for a tooth, and incredibly heavy.
 On my first visit to Arctic Canada, to a tiny Inuit village called Pond Inlet on the north of Baffin Island, there is a general store that serves the community and behind the door of the manager’s office were seven narwhal tusks for sale.  They looked like beautiful works of art, with a hint of algae in the spiral grooves, a polished tip where the animal may have rubbed it in the sand on the seafloor, and a hollow core where the tooth’s pulp and nerve endings would have been found.   When I returned to the store a week later after camping 60 miles away, all the tusks had been sold to tourists who had arrived on a small cruise ship.  They were priced at about $125 per foot, with the biggest one going for more than $1,000.
That’s a lot of cash for a narwhal’s left tooth.

2 comments:

  1. Of what actual use is the tusk? Spearing food? Fighting?--
    WHY did it evolve like that and then be the only creature which has such a thing— or were there others in early history.
    Do tusks ever break in the course of a narwal's lifetime?

    ReplyDelete
  2. There has been lots of discussion over the years about why narwhals have a tusk. Most biologists believe it is a 'secondary sexual characteristic' like the deer's antlers or the peacock's feathers, to demonstrate dominance over other males and to attract the females. I'll discuss the ongoing disagreements on this topic in a future posting. Tusks do break on occasion, so that is not an unusual occurrence, though no one knows exactly how or why it happens.

    ReplyDelete