Dear WC;
        A perennial topic, but nobody seems to have any exact numbers, since i
don't think anyone is keeping track in a systematic manner, and
molluscan taxonomy is such a nightmare (especially for the more
multitudinous families such as Turridae!!) that even if someone WERE
trying to keep a semi-accurate count, it would contain many synomyms,
nomen dubium, etc.  I think there are more terrestrial spp than marine
by a modest margin, and there must be over 100,000 valid decsribed
species overall at the moment (3 or 4 new spp are assigned a moniker
(ie, are described) per day - even i have  a half-dozen spp i could be
writing up if i had a few more Round Tuits!), so that means perhaps
45,000 are marine, with at least 300 marine families.  i have no idea
regarding the proportion of Nudibranchs, Saccoglossans and other
shell-free marine spp, but it would not be a stretch to say there are at
least 35,000 described marine shell-bearing molluscs that could be
collected by a determined person with tons of cash to mount expeditions
to the far reaches of the World Ocean and a LOT  of time on their hands
- and probably another 10 to 15,000 undescribed spp without too much
trouble, for a reasonable total of 50,000.  In reality, collections with
over 20,000 marine spp are very rare.  Given the very poorly-sampled
diversity probably present in the myriads of  small-scale habitats in
the deep sea, and the fact that the pace of molluscan species decription
is speeding up rather than slowing down, i would personally not be
surprised if the total for marine molluscan spp eventually came in at
over 300,000 - ie, if we can get to them before they start going extinct!!!

        Anybody have more accurate figures or better guestimates than these
ball-park numbers??


From the cool, moist, VERY green land of New Scotland,
Ross Mayhew.

> Subject: How Many?
> Date: Mon, 22 Jul 2002 12:11:24 EDT
> From: William Corey <[log in to unmask]>
>
> Can anyone offer a figure on the present total number of Families and
> total
> valid species of marine mollusks (please cite reference ) ? WC Thanks.
>