female Whelks (Busycon sp.) are larger than males - but it looks like they
have the same number of whorls.
shells of some freshwater mussels (Villosa & Lampsilis) show a difference -
the female shell is 'fatter'.
Amy
 
>Thanks Paul
>I was aware that nautiloids retained sexual dimporphism, although I wasn't
>aware of what it was.  I believe also that in the Paper Nautilus, the
>shell is internal to the female only.
>I was more thinking about other molluscs.  I know that some are
>protandrous and change during their lifetime from male to female.  Are
>there any gastropod or bivalves where the male shell is noticeably
>different from the female shell?
>
>Paul Monfils wrote:
>
>> Hi Nora,
>> The ancestors of those extinct fellows have kept up the practice.
>> Sexual dimorphism is seen in the shells of Nautilus.  One sex (female
>> I think) has a wider, somewhat angular shell aperture, while the other
>> has a narrow, more straight-sided aperture.  There was a discussion of
>> this topic on Conch-L some months back.
>> Regards,
>> Paul M.
>> Rhode Island
 
 
Amy Edwards, Program Coordinator ------ [log in to unmask]
 
Museum of Natural History        --------        phone (706) 542-4137
University of Georgia            --------            FAX 706-542-3920
Athens, GA 30602-1882       --------       http://museum.nhm.uga.edu/
-------------------------------------------------------------------
"A man's mind, stretched by new ideas, can never go back to its original
dimensions."             Oliver Wendell Holmes