>Over years of diving and collecting I have occasionally observed
>live individual specimens that are missing their operculum. This
>seems to occur randomly through predation, accident or whatever
>irregardless

You mean regardless...

>of Family or species. I recently cleaned a nice specimen of
>Megasurcula carpenteriana that had just a trace of an operculum.  It
>was thin and translucent. This species usually has a very dark horny
>operculum similar to a strombus.

Some species are just very variable individual opercular development.
Sassia kampyla has a range of ovoid opercs which can have a marginal
or central nucleus. Ranellid opercs can vary a lot in size within a
species. I have collected Volutomitra banksi with a minute operc
(1mm; shell 25mm) and others with no operc whatsoever; the latter
lacked a functioning gland.

Occasionally, too, an abnormal specimen of an operculate species will
be hatched without a functioning gland.

>My question is:  Do species that normally have operculum re-grow
>them when they are lost?

Provided the opercular glands have not been destroyed, the operc
should resume growing if it's been torn off. However, unlike the
shell, the missing parts of the operc will not be replaced, as the
gland is fixed in size & position on the posterodorsum of the foot
(the shell can be repaired because the mantle is a large free mobile
flap).
--
Andrew Grebneff
165 Evans St, Dunedin, New Zealand
64 (3) 473-8863
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Fossil preparator
Seashell, Macintosh & VW/Toyota van nut
I want your sinistral gastropods!