Hi Paul.....I thought I read that the general evolutionary progression
for these groups was marine to land and then from land to fresh water. If
this is true (and I'm not at all sure it is, but it makes sense), then the
bivalves would have evolved TWICE....once in a marine environment and once
in a freshwater environment. Does that seem likely?....Norman

Norman Frank
Miami FL


----- Original Message -----
From: "Paul Monfils" <[log in to unmask]>
To: <[log in to unmask]>
Sent: Saturday, June 02, 2001 10:08 PM
Subject: Re: The Question Man Asks---


> Hi Q!
>
> Nope.  Only two classes of mollusks have made it to fresh water -
> bivalves and gastropods; and only one class has made it to land -
> gastropods.  All the others (chitons, tusks, cephalopods,
> monoplacophorans, gastroverms) are strictly marine.  Bivalves are poorly
> equipped for terrestrial life from just about every viewpoint -
> locomotion, feeding, respiration, excretion, reproduction, etc.
>
> Paul M.