What a good job you did at covering the abnormal cowries, Wes. That book is
super. Some of the shells illustrated are amazing. I've always thought
freak shells were, well, freaky!  That is, until I met the "Porcelaines
Mysterieuses de Nouvelle Caledonie" by Pierson and Pierson. Wow!  (BTW,
remember "porcelaines" means "little pigs," whence we derive our word for
"porcelain".)
 
 To what you said, Wes, I have other points to add and questions that have
occurred to me in observing a lot of these shells.
 
1. There are also melanistic cowries off Queensland, especially Tryon
Island. Is there any geologic peculiarity or metal or pollution in the
water there? What other localities do people have melanistic cowries from?
C. tigris gets a big black blotch in a certain area in the Philippines, I
believe.
 
2. I understand that nickel mines are one of the suspicious factors in New
Caledonia.
 
3. Rust on wrecks causes dark, rusty red shells in some of the Cyp. lynx
and arabica and pantherina, etc  in the northwestern Indian Ocean and Red
Sea as well, I think. Isn't this akin to "melanism" in the sense that it is
excessive deposit of a pigment, though a different pigment than melanin?
 
4. Note that not all oddities from New Caledonia are melanistic. Rostration
has been mentioned as another effect of whatever the factor is in New
Caledonia. And rostration is also to be seen in shells from off Tryon Is.
Q'ld. Also, I have seen a New Caledonia Cyp moneta which was quite heavily
rostrate and had an intense deep yellow stripe down its back. The rest of
the shell was white. This is an intensification of the yellow pigment just
as melanism is an intensification of the black one. But a localized
intensification, not over the entire shell.
 
5. Most of the really rostrate and/or melanistic specimens I have seen are
very heavy shells for their size. And it has already been stated that none
of the affected shells are juveniles. Could it be possible that these are
all very mature shells and that the rostration and melanism or
intensification of other pigments are the effects of some external factor
like metals in the water, in combination with age. Age is the factor I am
aware of in senile Strombus gigas, the ones Clench named Strombus samba.
They develop a very heavy shell with aperture narrowed by shelly material,
and the aperture gets an aluminum-like glaze ? Also it seems to me that it
would take some doing -- energy and resources and time -- to produce some
of those "Napoleon's Hat" rostrate Cypraea stolida one sees at fantastic
prices! (Plus more energy and resources to drag it around!) Are there a lot
of unaffected but otherwise elderly cowries in the Prony Bay area of New
Caledonia?
 
6. I don't know a lot about the concept or content of pigments.  Is this
phenomenon of darkening in cowries always melanism, a laying down of the
pigment melanin which I believe is dark or plain black?  Or can it be an
excess of red pigment? Or just an excess of pigment? The dictionary would
seem to indicate the latter, yet my Brittanica says it is black pigment.
Cyp. cribraria forms its very familiar normal pattern of red pigment. But
it appears, when one observes a series of such shells in all degrees of
melanistic development, that the dark shell is dark through the heavy
deposition of red pigment, not black. And so the abnormal New Caledonia  C.
cribraria shell is not truly "melanistic," as I would understand the term.
 
Whoa!  I didn't mean to get to 6!
 
Ross asked why this tendency toward deformity of pattern and shape is the
case with cowries more so than other shells. I would say that, aside from
localized melanism and rostration, thay are not.  But cowries are so smooth
and glossy, often regular and specific of pattern, and smoothly and
regularly rounded in shape, that deformities are just more evident.
 
Also the incurving of the outer lip at maturity is going to accentuate any
injury the animal sustains at that point in its development from bulla to
adult. And bites out of the mantle are exaggerated hugely in any animal
that keeps polishing its shell and adding to its pattern the way cowries do.
 
 Then maybe, given the resourcefulness at escape and cone-foiling, and the
clever maneuverability we have witnessed second hand in Don's aquarium,
many cowries live through attacks that would end fatally in other less
resourceful groups. (I'm pulling for your C. lynx, Helmut! )
 
Lynn Scheu
[log in to unmask]
Louisville, KY, home of the best silent auctions COA ever had!  Wait til
you see all the cowries!  And I KNOW there are some melanistic cypraea in
the Bid Auction.