Subject: Odontocete teeth

Patrick Miller (omalley@cetacea.whoi.edu)
Wed, 22 Jan 1997 12:14:34 -0500

>Hi,
>I'm an outdoor educator at a small science center and occasionally
>conduct programming on whales.  Kids are always asking about baby whale
>teeth.  Specifically: Are toothed whales born with teeth?  If so, are they
>baby teeth that will be lost later?  Hope you can help me on this one.


>Thanks,
>Rita Rogers

------

Dear Rita -

When toothed whales are first born, they don't have any erupted teeth;
that is, the teeth are present but still below the gum line. As they
grow, the teeth begin to erupt, and it may take many months before
all the teeth have erupted. The teeth at the very front of the mouth
are typically smaller than those on the sides or back and appear to
erupt last. If you run your fingers along the gums of a young dolphin
or porpoise you can often feel the teeth beneath the gums.
        Toothed whales do not lose their teeth, but maintain the same
ones. Their teeth grow throughout their life-time, but growth fluctuates
over time, producing alternating layers of more and less dense dentine.
If you section a tooth, you can see these alternating layers in much
the same way you can see the rings in the trunk of a tree. In some
species, the rate of formation of these rings is known (often annual),
and therefore provides an indicator of age. In some older animals, the
tips of many teeth are worn down from use, revealing their inner rings.

				yours in whale research,

					-Patrick