Try these out for answers:
 
> 1.  Why are such projections so rare in bivalves?
--In my Hawaiian experience, most bivalves are in the sand or in
--a crevice-laced location, which offers at least some refuge
--from hungry lobsters (which, in Hawaii, have no serious claws
--for crushing).
 
> 2.  Why are spines and flutes found primarily on those bivalves that
> are LEAST likely to be swallowed (sessile types like Spondylus,
> massive types like Tridacna)?
--It might be tough to find the right spots to hold a clam closed with
--lots of spines sticking out. (See my description some time back about
--how lobsters 'strangle' bivalves.) As for Tridacna, show me its
--natural predator and I'll try to walk on water getting away from it!
 
> 3.  Why don't non-spiny gastropods living in the same habitat with
> the spiny types get wiped out by predators through selective
> predation (Murex capucinus among Murex cichoreus for example, or
> Murex trunculus among Murex brandaris).  Do the "smoothies" have some
> other, equally effective form of protection?
--Gosh! Cowries are my main concern and they hide most of the time. But
--there isn't any single NATURAL predator wiping out large numbers.
--Crabs get some, octopi get some, cones get some, fish get some,
--even flatworms can kill cowries (see THE CAPTURED COWRY,
--Observations).
 
> 4.  Why are various modern gastropods (Cypraeidae, Strombidae, etc.)
> LESS spiny than their extinct ancestors?
--Having lots of spines probably made it difficult to hide from
--increasingly successful predators. It's tough to drag all those
--spines into a hole too small to be dragged out of.
 
Why do we have little fingers expect that the lemurs had the
eqivalent? And did they even need that? How many lemur lives were
saved by having one-third as many digits (and scrawny ones, at that)?
 
Aloha,
 
Bob Dayle