What is a rare shell anyway?  Is it something like a rare bird or a rare
mammal?  A mammal or bird is considered rare when few individuals of the
species are observed after exploring most of its available habitat over a
period of time.  We know that the next mountain peak is not going to be
covered with condor nests, the next valley is not going to be crawling with
giant pandas.  Why?  Because those peaks and valleys have already been
explored.  Otherwise, who could say with any degree of confidence that pandas
and condors are rare?
Some folks try to apply the same principles to marine mollusks, but it just
doesn't work.  Only a minute percentage of the ocean floor has been sampled or
observed, and then only by the crudest of methods.  A dredge dragged along the
bottom for a mile or so may pick up many interesting organisms, and some of
them will be much more common than others.  But to call a species rare because
such dredging operations failed to pick up a large number of specimens is
simply jumping to conclusions.  Field mice would be considered rare if the
only way of collecting them was by dragging a net behind a slow-flying plane.
In fact, when we classify marine organisms as "rare", we really mean rare in
collections, not rare in nature.  To equate those two ideas is risky business,
and those who jump to such an unwarranted conclusion are quite likely to be
proven wrong.  Time and time again, molluscan species once considered great
rarities have been found to be quite common.  In the 1800's, one of the most
coveted "rarities" was the precious wentletrap, Epitonium scalare, a shell
which can now be had for five dollars.  In 1960, fewer than 50 specimens were
known of Lister's conch, Strombus listeri, and newly discovered specimens were
selling for $1,000.  Today it is a common shell.  Or, more accurately - it was
always a common shell, but that fact had not yet been established in 1960.
Other species once considered great rarities include Cypraea nivosa, Cypraea
hesitata, Cypraea teulerei, Scaphella junonia, Thatcheria mirabilis, Murex
beaui, Murex elongatus, Tibia martini, and many others.  Recently a trawler
off the coast of Mozambique brought up about 1,000 specimens of Fulton's
Cowrie, Cypraea fultoni.  Immediately, some responded with indignation and
even outrage over the wanton destruction of such a large number of such a rare
species.  Such a reaction misses the point entirely.  This event did not
represent the decimation of a rare species, but rather the discovery that
Fulton's cowrie, like so many others, is NOT a rare species.  It is in fact, a
fairly abundant species, once you know where to look.  R. Tucker Abbott had it
right when he wrote, in his classic "Kingdom of the Seashell", "It might well
be said that there is no such thing as a rare marine shell, since any species
living today must have a large enough population, certainly of several
thousands of individuals, to sustain the species".
Please note, I am speaking here of marine mollusks.  A fresh water species
confined to one stream, or a land snail endemic to one small island are fairly
easy to monitor, and their relative abundance can be reliably assessed.
Therefore, they can accurately be declared "rare", and if necessary
"endangered" and in need of protection.  The collection of a single specimen
of such a species could rightly be condemned as a criminal act.  However, the
harvesting and subsequent sale of a deep sea Pleurotomaria (slit shell) known
from only five specimens is so far removed from that scenario as to defy any
rational comparison.  The likelihood of picking a slit shell off a vertical,
organism-encrusted rock wall in 1,000 feet of water, by dangling a box on a
rope is so remote that the fact it was done successfully five times is, in
itself, proof positive that the species is common in its natural habitat.
I could go on.  And on.  But I won't.  Not right now at least.
Regards,
Paul Monfils
Rhode Island, USA