You will receive replies in the 100,000 range.  However, these are not
authoritative.  As it just happens, I asked myself the same question about a
month ago and made a new years resolution to survey all the literature, create
a data base to prevent any double counts, and make a definitive count of all
published species.  I restricted my search to Gastropoda amd Pelycepoda.  I
eliminated all synonyms.  I included all unidentified species published as
"sp.," "sp. aff.," "cf.," etc. reported in marine and fresh water surveys.
However, I counted these only as one half to adjust for duplicate "sp's."  I
just finished about dinner time.  The count was 132,306.5.  Tomorow I leave
for a world wide tour to verify all material reposed in museums to be sure the
same shell species has not been given two names.  I should be back home by
Sunday at which time I'll provide an update.
 
I hope you find this data helpful.
 
Marlo
Florida
 
Stephen McMahan wrote:
 
> Hi friends,
>
>                 Can anyone tell me how many different species of mollusks
> there are in the world today? This would be "known" species of coarse. I'm
> just curious. Thanks.
>
> Stephen McMahan