Bivalves; and Feduccia newsrelease
barry_roth at YAHOO.COM
Fri Aug 16 13:34:28 CDT 2002
Gosh .. whether to reply to this one here or on the Mollusca list!?
Neither of these examples supports the major argument very well. Shipworms are fully bivalves. They happen to have an odd relation between the shell and the main body, but the bivalve parts (siphons, stomach, adductor muscles, etc.) are all there. Similarly, slugs are manifestly gastropods in their component parts and organization. Nothing against the exercise of the imagination, but this is a little like saying, if humans can evolve (near) hairlessness, why couldn't they evolve into tunicates as well?
Ken Kinman wrote:..., if a typical bivalve can evolve into something like a shipworm, then bivalves could also evolve into worms which have lost the shells altogether (especially sipunculids, but perhaps other spiralian worms as well). Could nemertines or some flatworms actually be very-derived bivalve "slugs"? If snails can do it, why not bivalves?
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