Here's an observation from years of collecting ALL dead (and many living)
cowries:
The extremely thin shell of the growing juvenile is often damaged by forces
acting on it (anything from waves action to would-be predators). I have several
specimens where the renewed shell growth (bulla stage) does not resume its
typical smooth shape, but becomes rows and columns of small plate-likes pieces
of shell. I suppose this could be some polyplacaphoid DNA kicking in after the
trauma to the mantle tissue.

As I recall (I'll have to find some examples among the many specimens), the
lines of the sutures between the plates correspond to the tooth structure. Thus,
my surmise at the time was that the teeth are relics of an earlier ancestor
which have never inhibited the cowry life cycle enough to be 'shaken out' by
evolutionary pressure. Somewhere in http://cowry.org I have commented on the
lack of function for this particular feature of the cypraeid shell.

The teeth don't prevent molluscavores like Conus textile or C. marmoreus from
inserting their stomachs into the cowry shell, nor do they stop crabs from
crushing the shells, or stop octopi from drilling into the shells and then
reaching to remove the dead animal's flesh.

Perhaps another cowry collector has seen the above-mentioned plate-like
structure that occurs after the thin cowry bulla shell is badly damaged.


Bob Dayle
http://cowry.org



Quoting Paul Monfils <[log in to unmask]>:

> I received a query about the apertural teeth of cowrie shells ­ namely, do
> they have any purpose or function?  I couldn¹t find a word on the subject in
> any of the standard volumes on Cypraeidae (Burgess, Lorenz & Hubert,
> Liltved, etc.) or in any of several texts on molluscan development, anatomy,
> ecology, etc.  Does anyone have any information on this?  Are the ³teeth²
> strictly decorative?  Ovulidae seem to get along just fine without them.
>

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