Hello Art,
I asked Emily Vokes the same question a year ago.  It seems that the long
spines are the most energy efficient means of increasing effective size
(i.e.diameter) without actually having to increase body volume.  This
prevents predators (i.e. fish) that would normally prey on gastropods of
that body volume from preying on that particular species.  Larger fish
with bigger mouths could eat the snail, but the small body volume of this
murex would most likely make it not worth the energy.  It's like making a
sandwich that's too big to eat without having to put any extra meat in it.
Greg Herbert
Loyola Univ.
New Orleans, LA
 
 
 On Mon, 26
Jan 1998, MR ART WEIL wrote:
 
> Dear Kurt et al;-
>      Thank you for the reply. It seems that our present state does
> simply leave divisions in the eye of the beholder---or under his
> microscope.
>      Here's something else I've wondered about. I have this lovely
> Murex pecten with its great spikes and a few other almost similar
> species. The spikes obviously serve as protection---but against what?
> The spikes also probably keep the mollusk from doing much digging to
> get away from preditors. Do other mollusks living in a similar biome
> have other protections against similar predators? Do the appendages
> on a carrier shell serve as protection---or just camoflage?
>     You remember TV used to have the "Answer Man". I'm the "Question
> Man".
>              Art
>