Shape is one thing and I agree there are some fantastic tenting and other shapes
drawn.

Regarding color - remember we are looking at them in various lights.  The true
to life color is through xx meters of water.  As something hunts it - the tinted
water mixes with the tinted shell for a third color - perhaps out of range of
the aggressor to see.   E.g. we don't see into the U.V. but deep purple for most
of us.
We don't see Infra Red while the eye sees Deep red.  An attacking shell might be
very
limited in color range. Now how can that be measured :-)

Colors can add in frequency and subtract in frequency.  Color shift might be
just the thing.

Martin [ Physics and Electronics background thoughts ]

On 9/8/2010 8:38 PM, Ellen Bulger wrote:
> I saw some pretty nifty variations on Pectin tenting at the COA, and even more
> stunning variations in cones, notably the textile cones. And I'd been
> wondering about them. If the darker portions of the shells are stronger, and
> if this dark pigment is expensive for the animal to produce, a pattern like
> tenting might be an economical structural solution. And the various lovely
> variants I was seeing were mutations that tweaked the tent-producing
> algorithm. That the results are "delightful" to human eyes says more about us,
> about pattern recognition, about the nature of our sight and the wiring of our
> brains, than it does about any intent on the part of the mollusk.
>
> But oh, they ARE lovely.
>
> On Wed, Sep 8, 2010 at 10:55 AM, Stanley Francis <[log in to unmask]
> <mailto:[log in to unmask]>> wrote:
>
>     *As a devoted Pectinidae collector for many years,I have read the recent
>     exchanges on shell colour with great interest.  This has probably been the
>      most imponderable question, which has ever been raised with me at so many
>     shell talks.*
>     *One can understand the reasoning that that the colour of our garden snail
>     shells is attributable to the colour of its waste products. Food source is
>     also also offered as the reason for colour sub-forms. The influenze of
>     light is also a reasonable explanation with certain varieties , but at the
>     same time we find that many other varieties have equally colourful left
>     and right hand valves.*
>     *You always return however to 'albino' forms and say to yourself "
>     whatever the explanation, if it is waste, food products or influence of
>     light that produces such beautiful colours, how can we have so many pure
>     white albino forms ?".*
>     *Stanley Francis.*
>
>         ----- Original Message -----
>         *From:* Paul Callomon <mailto:[log in to unmask]>
>         *To:* [log in to unmask] <mailto:[log in to unmask]>
>         *Sent:* Tuesday, September 07, 2010 5:54 PM
>         *Subject:* Re: [CONCH-L] scallop shell colors
>
>         There are any number of theories about shell coloration, but in very
>         few cases has it been shown to be a deliberate camouflage or tactical
>         ploy. It has been found that colored parts of the shell are stronger
>         than the non-colored parts (in some species at least; the black parts
>         of Cittarium pica resist erosion more than the white parts, for
>         example) and if that is so for all shells, then the presence of netted
>         and zigzag patterns might represent optimum reinforcement of the shell
>         using a limited supply of pigment. For the most part, however,
>         patterning  in things like scallops remains unexplained, though simple
>         colors like those found in Chlamys nobilis are just genetic. Variation
>         for its own sake, the best insurance a species has against mass
>         obliteration.
>         PC.
>         Paul Callomon
>         Collections Manager
>         Malacology, Invertebrate Paleontology and General Invertebrates
>         Department of Malacology
>         Academy of Natural Sciences
>         1900 Parkway, Philadelphia PA 19103-1195, USA
>         Tel 215-405-5096
>         Fax 215-299-1170
>
>         >>> John Varner <[log in to unmask] <mailto:[log in to unmask]>>
>         9/7/2010 12:32 PM >>>
>         The color variation as camoflage would seem more plausible if scallop
>         "swimming" wasn't such a haphazard affair.  They aren't consistantly
>         oriented with one valve up, one down.  Also, with bay scallops in New
>         England, at least, one valve is sometimes rayed, the other not, or
>         both are colored, and differently.
>         What preys on scallops, and how well do they see?
>         As with so many shells, in which colors are obscured by encrustations,
>         periostracum, or just low ambient light in the animals' natural
>         environment, scallop shell coloration seems related to something other
>         than camoflage or vision.  Maybe a sense we are not endowed with, or
>         maybe it's just random, and since it doesn't amount to a large net
>         evolutionary selector, it muddles through....
>
>         - John
>
>
>
>

--
Martin H. Eastburn
@ home at Lions' Lair with our computer lionslair at consolidated dot net
"Our Republic and the Press will Rise or Fall Together": Joseph Pulitzer
TSRA: Endowed; NRA LOH&  Patron Member, Golden Eagle, Patriot's Medal.
NRA Second Amendment Task Force Originator&  Charter Founder
IHMSA and NRA Metallic Silhouette maker&  member. http://lufkinced.com/

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