Rosemary,

This happened several years ago and I can't recall his name.  I can recall
his image but not his name.  I'll contact my "X".  Perhaps she can recall.
When either of us remembers, I'll try to contact him and test HIS memory.

If I lived near the Gulf, I might collect some shells and take them to a
shallow, fairly fast moving and (most important) 'gator -free stream.  I'd
drop a shell in to see whether the current was fast enough to make it spin
at all.  If so, then I'd drop them in one at a time, outside-down.  Record
it's length, whether it is a right or left valve and whether it spun
clockwise, counterclockwise, both or neither.  Then, retrieve the shell and
try it once or twice more before testing the next shell.

Come to think of it, we do have thundering herds of Clinocardium nutalli
here.  There's no shortage of streams nor rain to make them move.  Maybe I
can do this myself!

  _____

From: Conchologists List [mailto:[log in to unmask]] On Behalf Of
Rosemary Payne
Sent: Monday, January 23, 2006 10:58 PM
To: [log in to unmask]
Subject: Re: FW: Re: Effects of collecting shells from beaches, and change s
in the numbers of shells on beaches


Any chance of gettng hold of a copy of the paper?  Was it ever published?
I've come across this suggested explanation before, but haven't come across
details of any experimental test - sounds interesting.

Bas

----- Original Message -----
From: Brenner, Bob <mailto:[log in to unmask]>
To: [log in to unmask] <mailto:[log in to unmask]>
Sent: Monday, January 23, 2006 8:02 PM
Subject: Re: FW: Re: Effects of collecting shells from beaches, and change s
in the numbers of shells on beaches

For whatever this is worth....

Some years ago, I noticed that 23 of 25 cockle shells my kids gathered from
Casey Key beach were, I believe the left valves.  I mentioned this to one of
my co-workers nad he said that he had done a short paper on that phenomennon
while an undergraduate.  The jist was that the valves spin in opposite
directions when caught up in an alongshore current.  He painted several of
them, dropped them in the "first trench" and spent a few days watching them.
Very soon, half of them would disappear into deeper water while the others
remained.  When the tide changed, the direction of the current reversed and
the effect was the same - but the valves that remained in the first scenario
spun into deeper water while the others remained.

I've often wondered whether the ratio changes from summer to winter -
assuming that the alongshore di8rection changes.