Paul is right in that one can't tell by examining one shell if the cause of
an abnormality was a random mutation or pollution or something else other
than a visible injury. One way to test this would be to raise the molluscs
from a polluted area in clean water in the laboratory to see if the same
abnormality still develops. Parasites could also cause anatomical
abnormalities. Unless there are reference specimens, for example shells of
snails raised with parasites, whose abnormalities can be definitely linked
with a known causative factor, it would be difficult to reach definite
conclusions about the causes of shell abnormalities.

Aydin

-----Original Message-----
From: Conchologists of America List [mailto:[log in to unmask]]
Sent: Thursday, March 02, 2000 11:26
To: [log in to unmask]
Subject: "Freaks" - pollution or genetics, "other" - how to tell?


There are several categories of freaks (injury, disease, physical growing
conditions (odd shapes caused by cramped conditions), pollution, natural
conditions
and chemicals (water temp. and food source and supply variations, high iron
or
manganeese concentrations, etc.), and of course genetics.).  My question is:
how
can one tell when pollution is the likely cause of a particular malformation
or
color variant?  With some specimens, it seems easy (as in dwarfism due to
chemical
pollution, as occurs near pulp and paper plants sometimes, which discharge
chlorine
and other nasties), but with many others, it seems rather tricky.  Are there
some
general guidelines folks have worked out to help tell the differences
between
man-caused, and natural freakazoids?
-Ross.
--
Ross Mayhew: Schooner Specimen Shells: Http://www.schnr-specimen-shells.com
"We Specialize in the Unusual"
Phone: (902) 876-2241; Fax: (603) 909-8552.
But try to find "something for Everyone"!!
Snail Mail: 349 Herring Cove Rd, P.O Box 20005, Halifax, N.S., Canada, B3R
2K9.