g.read at NIWA.CO.NZ
Sat Aug 17 16:45:29 CDT 2002
> Therefore, I will continue to refer to Sternaspid paired shields as
> "shells", and also assume that they are homologous to bivalve shells,
> whether they are directly descended from bivalve molluscs or not (but my
> intuition is that they are bivalve descendants). I may be rather
> imaginative, but it is based in a very wide reading of the literature that I
> have access to.
Ken, don't forget the serpulid polychaetes - they have whole houses built of
"shell". Clearly, molluscs manque.
Let's keep our feet on the ground - the ability to secrete and to dissolve
calcium carbonate is probably universal across the animal kingdom. Ad hoc
'opercular' or shield structures evolve when appropriate. In the case of the
sipunculan genera with shields or caps - they happen to live in rock & coral
Geoff Read <g.read at niwa.co.nz>
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