Paul will probably give a more detailed reply than this but remember when
you are boiling shells to put them in cold water and then bring the water to
a boil.  Don't drop them into boiling water.  When I did this to some big
moon snails I collected it resulted in cracks along the lip edge which then
broke when I tried to remove the animal.  And it's hard to find nice big
moon snails here in Maine. :-((
 
Beth
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-----Original Message-----
From: Jose Eduardo de Alencar Moreira <[log in to unmask]>
To: [log in to unmask] <[log in to unmask]>
Date: Thursday, January 07, 1999 8:45 AM
Subject: [CONCH-L] RES: Stinking Astraeas
 
 
>Paul,
>
>Many thanks for your reply. I understood much better what is originating my
>stinking problems.
>
>Just two more questions. Some shells can be boiled and others (like
cowries)
>can't. What shells sould not be boiled? What do you suggest to avoid or
>minimize these reeky problems in shells that can't be boiled or if you are
>in a trip?
>
>Cheers,
>
>Eduardo
>
>
>        ----------
>        De:  Paul Monfils [SMTP:[log in to unmask]]
><mailto:[SMTP:[log in to unmask]]>
>        Enviada em:  Quarta-feira, 6 de Janeiro de 1999 19:26
>        Para:  [log in to unmask] <mailto:[log in to unmask]>
>        Assunto:  Re: [CONCH-L] Stinking Astraeas
>
>        Hi Eduardo et al,
>        Most of us have probably encountered certain lots of shells, or at
>        least individual specimens, that were memorably malodorous.  I have
>        not noticed that any shells smell much if cleaned promptly after
>        collecting.  So, optimal handling will usually prevent odor
>problems.
>         However, travel and vacation plans often preclude ideal handling
of
>        collected materials; and I assume you are speaking of shells in
this
>        category, which have hung around unrefrigerated for several days or
>        more before cleaning, a situation that many of us have likely
>        encountered.
>        As long as the animals remain alive, no unpleasant odors usually
>        develop.  Some species may survive a couple of days in a collection
>        bucket, if kept in a relatively cool area.  Some may survive a week
>        or more if refrigerated.  But sooner or later the critters are
going
>        to expire.  In the trunk of a car on a hot summer day this will
>occur
>        sooner - much sooner!  In any case, as soon as they give up the
>ghost,
>        two processes start to occur.  First, enzymes and other substances
>        that were kept under control in the living molluscan cells are
>        suddenly released, and begin to digest the tissues from within, a
>        process known as autolysis.  Secondly, microorganisms (primarily
>        bacteria) which were also kept at bay by the various chemical
>        defenses of the living animal, start to proliferate, feeding on and
>        invading the dead tissues, a process known as putrefaction.  Both
>        these processes result in the breakdown of cellular components into
>        simpler chemicals.  The properties of a substance often differ
>        markedly from the properties of its component substances  (for
>        example, the salt we sprinkle on our food is composed of an
>        explosively reactive metal and a poisonous gas).  Therefore, when
>        non-odoriferous substances decompose, some of the resulting
>breakdown
>        products may be extraordinary malodorous.
>        The intensity of the odor depends on several factors, including the
>        volume of tissue involved, the rate and extent of decomposition,
the
>        specific organic compounds present in the tissue, and the identity
>of
>        the microorganisms responsible.  Of these four, we have no
influence
>        over the last two, so our odor-control efforts have to be focused
on
>        the first two.  The first point is, I think, self-evident.  All
>other
>        factors being equal, a big snail rotting in a bucket will smell
more
>        than a small snail rotting in a bucket.  Also, a shell with half
the
>        soft parts left inside will smell more than an identical shell with
>        90% of the tissue removed.  However, the present discussion
involves
>        those times when it not possible to remove the soft parts from the
>        shell promptly.  In such cases, preventing the production of
>        odoriferous substances means preventing autolysis and putrefaction.
>        Both the enzymes of autolysis and the organisms of putrefaction
>        require certain physical conditions in order to be active, most
>        notably the presence of water and a suitable temperature; therefore
>        both processes can be prevented or arrested by removing one of
these
>        necessary elements.  If the tissue is thoroughly desiccated before
>        odorous compounds have a chance to develop, then such substances
>will
>        not develop as long as desiccation is maintained.  This method is
>        often used with very small gastropods.  Water is removed either by
>        alcohol extraction or simply by drying them in the sun or in a low
>        temperature oven, and the resulting specimens are virtually
>odorless.
>         However, if such specimens are exposed to moisture, then bacteria
>and
>        fungi (as well as other organisms such as mites) may eventually
>break
>        down the tissues.  Many collectors are familiar with old specimens
>        containing a sawdust-like residue of slowly decomposed tissue.  Due
>        to the very gradual rate of decomposition, this does not produce
any
>        noticeable odor.  Also, collectors working with old shells have
>        probably found specimens which "rattle" when you shake them, due to
>a
>        chunk of shrunken, "mummified" tissue which has not decomposed in
>        fifty years or more, because the shell was stored in dry
conditions.
>
>        Alcohol retards autolysis and putrefaction not only by extracting
>        water from tissues, but also by denaturing and inactivating
enzymes,
>        and by killing many kinds of microorganisms on contact.  However,
if
>        I may state the obvious, it produces these effects only in tissues
>        that are in direct contact with it.  Unfortunately, the tissues of
a
>        gastropod mollusc are encased in a long, impenetrable tube of hard
>        calcium salts (a gastropod shell is essentially a tube of gradually
>        increasing diameter, wound around a central core, and a 4 inch
Turbo
>        shell, if "unwound", might be a foot in length).  Alcohol can enter
>        the shell only through the aperture; however, the soft parts of the
>        animal extend all the way to the apex.  Therefore, when a gastropod
>        shell more than a few centimeters in length is placed into alcohol,
>        the fluid usually doesn't reach the tissue in the upper whorls.
>        After a few weeks' storage, when you remove the shell for cleaning,
>        what you find is a well-preserved, rock-hard foot (alcohol hardens
>        muscle greatly) which may be difficult to remove from the shell,
>        followed by a slimy, foul smelling mass of decomposed organ
tissues.
>        Except for very small specimens, all you can say about alcohol as a
>        temporary storage medium is - better than nothing!
>        A more reliable approach, when possible, is the use of temperature
>        extremes.  Boiling the shell with its enclosed soft parts, as
>someone
>        already mentioned, greatly retards the development of odors.  This
>is
>        because a temperature of 100' C (212' F) permanently deactivates
>        enzymes, and also kills most microorganisms.  Once boiled, shells
>can
>        be refrigerated for a couple of weeks without odor, or placed in
>        alcohol indefinitely without additional tissue changes taking
place.
>        (However, the soft parts are easier to remove immediately after
>        boiling, while they are still warm.)
>        Freezing the fresh specimens is also a good method of long-term
>        storage for eventual cleaning.  However, this method does not
>        permanently denature enzymes, nor does it kill many
microorganisms -
>        it only inactivates them while they are frozen.  In addition, the
>        freezing/thawing does extensive microscopic damage to the tissue
>        cells, and causes a certain amount of tissue breakdown in and of
>        itself.  As a result, such specimens, once thawed, should be
cleaned
>        promptly, as autolysis and putrefaction can set in quickly.
>        Personally, I have not noticed that particular species or genera
are
>        more prone to disagreeable odors than others.  I believe it has
more
>        to do with methods of handling than with taxonomic relationships.
>        However, some groups of molluscs tend to be smelly because their
>        shell shape or structure makes it difficult to remove all the soft
>        parts.  And, it is not inconceivable that some families of molluscs
>        might possess specific proteins with particularly odoriferous
>        breakdown products, not present in other families.  There is one
>        other good reason to avoid tissue decomposition before cleaning -
>        some breakdown products of organic compounds are acidic, and may
>        dissolve the shell, especially the relatively thin spire, from the
>        inside.  Or, if they trickle out of the aperture onto a glossy
>        columella, they may cause permanent dull, discolored, or pitted
>areas
>        on that part of the shell.
>        Regards,
>        Paul M.
>