So, are you saying that sinistral and dextral snails don't know how to make ends meet? So to speak.

Haven't they read the Chama Sutured?

David Kirsh
Durham, NC

On Wed, 10 Apr 2002 10:24:16 -0500 Russell Renka <[log in to unmask]> wrote:


I have read, from Geerat Vermeij I believe, that shell coiling may be explainable
from two factors.  First, right handed coiling may be a "founders
effect" that quickly became essential to aquatic gastropod species, not
because of a survival factor but rather because it was usually impossible
for a left-handed mutation case to reproduce successfully.  Thus we
regularly get left handed Cymbiola vespertilio among the vast P.I. harvest,
but they stay quite rare because they produce no progeny.  However,
I wonder if any controlled experiments have been done, with live left-handed
and right-handed C. vespertilio, to confirm this hypothesis.  I suspect
not, because the lefties are rare and valuable to collectors in dead rather
than live form, and because this is really difficult experimental stuff
to conduct in an artificial tank environment.
So second, a normally left-handed species like Busycon contrarium
has to be explained.   I read the speculative argument that one
stranded lefty somewhere in time-space got incredibly lucky, and met his
or her match, another lefty.  Voila!  Nature took her course,
all lefties were the result (suggesting that this is a recessive trait),
and they thrived.  Since this species uses the shell edge to lever
open Bivalvia species, maybe that left-handed lever conferred a serious
predatory advantage.
As a lefty myself, I know it's a nice advantage in certain athletic
pursuits, such as hitting kill shots in racquetball with the forehand from
deep left-side back court.
Mostly speculative, but I wonder if science has gotten any further than
this.
Russell Renka
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