I think that was the Shell Answer Man, actually.  The only guess I would
venture on the elaborate spines would be protection against some fish.  If
you sucked one of these porcupine-like things in your mouth, you'd probably
spit it out pretty quick.  The spines wouldn't help with crabs, etc., I
don't think.  Other species may have different ways to protect themselves,
i.e. noxious odor or taste, microhabitat, behavior, etc.
 
Kurt
 
At 10:55 AM 1/26/98 -0500, you 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
>