Thanks for the tips, Andrew!  I am asking Avril to alter the part about
various species using a thick, protective periostracum "overcoat" in
order to survive below the Carbonate Compensation Depth - that one just
slipped by me.  Much of the really technical stuff about variations in
the "Turrid notch" is not too relevant to the usual readership of the
article, which i am aiming at the Junior High to High school level.  //
I guess a little note about Thatcheria having several fossil (ie,
extinct) species, would be interesting - i tend to completely ignore
extinct species personally, except for selling a few every now and then
:--).//  Regarding the paucity of shallow-water Turrids,  which is odd
considering that Polychaete worms have no such pattern (although perhaps
the SMALL species that Turrids are able to successfully catch, are also
uncommon in the shallow water zone?  Anyone??) - i will leave it up to
Avril whether to modify the appropriate section of the article
accordingly - sounds like a good idea, however!! (Avril does all the
editing on the site now:  i just contribute a bit every now and then,
and lurk in the backbground in case she has a question or two i might be
able to answer.....).

-Ross M.

Original message:

     I am most pleased to announce that my Man and Mollusc web site has
a new Mollusc of the Moment
     page.  Ross Mayhew has written a fabulous article on those very
complicated turrids.  I hope you enjoy the
     article as much as I have.

     Please visit:  http://manandmollusc.net/mollusc_moment.html


Bravo Ross!

However I feel that I ought to point out a few things:

There is a depth in the oceans (which varies from place to place,
according to local conditions), called the
carbonate compensation depth (CCD), below which calcium carbonate
becomes particularly prone to
solution; dead shells below the CCD will dissolve, for instance the
abandoned tests of reproducing planktic
foraminiferans which rain down from the shallows. Shelled molluscs DO
live below the CCD, but are
protected by a periostracum; after death the shells will not last long.
Such animals are generally pretty
small.

Conacea... molluscan workers have lagged WAY behind other zootaxonomists
in this, and only recently have
begun adopting the "oidea" suffix. Brachiopod workers also lag...

While turrids sl are often extremely common and in deeper waters can
indeed make up a substantial
proportion both specieswise and in mass of the molluscan population, in
shallower waters they are often
entirely absent. You won't find them, for instance, on many temperate
rocky shores (here in southern NZ
you'd be very lucky to find one of the 2 Neoguraleus spp there, and in
BC, Canada there are none).

The turrid notch is highly variable; some subfamilies (eg Turriculinae)
have a shallow to deep narrow sinus
on the shoulder, which can also be a broad sinus which bows much of thre
labrum. Turrinae has a distinct
parallel-sided notch at the periphery, producing a selenizone similar to
that of Pleurotomariidae.
Borsoniinae varies from a notch nearly no sinus. Daphnellinae, which
includes Thatcheria, has a sutural
sinus, and Conus displays basically a dephnelline type of sinus.
Mangeliinae has at best a very faint broad
sinus, no more evident than in most Muricidae. It is noteworthy that
many turrids display a distinct stromboid
notch.

Thatcheria has several species... all but one fossil (and New Zealand
has 2 of these).


--
Ross Mayhew: Schooner Specimen Shells: Http://www.schnr-specimen-shells.com
"Shells to write home about!!"
Phone: (902) 876-2241; Fax: (902) - 479 - 1863
Snail Mail: 349 Herring Cove Rd, P.O Box 20005, Halifax, N.S., Canada,
B3R 2K9.