Ross,

A rather strange candidate for your omnivorous mollusc is Cypraea cervus --
the deer cowrie.  This was written up in American Conchologist Magazine
(maybe even back when it was the bulletin).  I don't remember the date but
Alta Van Landingham put a small, immature C. cervus (something like less
than an inch long) in an aquarium filled with rocks covered with algae.
There was also a Busycon caurica (I believe) in the tank.  She fed the
whelk, coquina clams and right away noticed the cowrie eating those clams.
Soon the cowrie was going through something like a pint of clams a day!  It
grew to adult size in less than a year although it still had juvenile
coloration.  It died about that time (Alta jokes it was probably from
indigestion).  Anyway, it did eat the clams even though it was not equipped
to open them.  She would freeze the calms which would then open up when they
thawed in the aquarium.

For you purests, I realize this does not make the animal an omnivore -- just
an opportunist.  But it is interesting.  All kinds of vegetarians will eat
meat if given the chance.  In the last ten years there has been a lot of
publicity about different monkeys (howlers for one) and chimpanzees actually
hunting.  Both animals once thought to be strictly vegetarian.  I know my
blue and gold macaw will chow down on fried chicken any time she gets the
chance.  So there are plenty of animals who will jump at the chance for
extra protein in that handy package called meat.

As for a vegen diet for man, I have no arguement with the health benefits.
I would miss the flavor however; I have grilled veggie burgers side by side
with my hamburgers for friends who won't eat meat and there is no
possibility of mistaking which is which -- on the grill or in the hamburger.
I also think this diet is a reflection of modern living and was maybe not
workable years ago.  It would be impossible to live and work in a climate
like Alaska by just just grazing on lettuce without modern supplements.
You'd loose weight all right -- all of your weight.

Oh, there is also a shell book out there that calls Strombus gigas a
predator!  Maybe he was thinking from the point of view of the algae?

Tom Eichhorst in New Mexico, USA