Below is an extraction from Chapter 2 from The Mollusks: A Guide to
Their Study, Collection, and Preservation (c. 2006), by Sturm, Pearce, and
Valdes (eds.) It includes the info on narcotization and hopefully all of
the references.

Any questions, let me know.

This is just one example of the information that can be found in this
volume..now I want all of you who do not own it to go out and buy a copy
;-)

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2.5 TECHNIQUES FOR NARCOTIZING MOLLUSKS

Before beginning the discussion of cleaning techniques, we would like to
discuss the topic of narcotization. Sometimes when mollusks are collected,
it is important to preserve the animal (soft parts) as well as the shell.
The process of narcotizing or anesthetizing will render the animal
senseless and relaxed. If the animal is left in the narcotizing agent for
a prolonged period of time the animal will die. If anatomical studies are
anticipated or if you want to minimize damaging the shell when removing
the soft parts, you will want to relax the animal by using a narcotizing
agent. While there is no single ideal narcotizing agent, there are some
recommendations that can be offered.

For terrestrial gastropods, the simplest way to relax the animal is by
placing it in a jar of water sealed so that there are no air bubbles in
the container. The animal will die in a relaxed position outside of the
shell (if one is present) within 24-48 hours (Pilsbry and Vanatta 1898,
Gregg 1944). As soon as the animal is dead, it should be transferred to
the appropriate preservative. A good, general-purpose one is 80% ethanol.
Some researchers use a mixture of 80% ethanol, 15% water, and 5% glycerin.
If this mixture is used, do not use jars with metal lids to store
specimens, as glycerin will accelerate the deterioration of the metal lid
(see Chapter 5). You can also use formaldehyde but then the tissues cannot
be used at a later time for DNA studies (formaldehyde cross-links proteins
making the DNA difficult to extract).

When DNA studies are anticipated, a 95% or higher concentration of ethanol
should be used as the preservative, and the animals should be preserved
immediately without drowning (Schander and Hagnell 2003). Another agent
that can be used for terrestrial gastropods is chlorethanone
(chlorobutanol) (Hubricht 1951, Clement and Cather 1957). One makes a
saturated aqueous solution of chlorethanone and then dilutes one part of
this solution with 10-20 parts of water. The snails are put in this
solution. Depending on the size of the specimen, it can take from 12-48
hours for complete narcotization. The specimens should then be transferred
to the preservative of
choice.

A. G. Smith (1962) found that chlorethanone also worked well for some
marine gastropods. Nembutal and pentobarbital have been found to be good
general narcotizing agents for a variety of freshwater mollusks (van der
Schalie 1953, Heard 1965, Runham et al. 1965, Meier-Brooks 1976, Coney
1993, Araujo et al. 1995). These chemicals are considered controlled
substances (substances of abuse potential) by the United States
Government. You may have difficulty obtaining them unless you have a
federal license to possess them or are working with someone who has such a
license. Barker (1981) found nembutal a good narcotizing agent for
pulmonates and Aquilina and Roberts (2000) found it good for Haliotis.

Craze and Barr (2002) used electrical-component freezing spray to kill
snails. This material is packaged as an aerosol spray and will cool to
-50°C. They found this material quickly froze snails up to approximately
30 mm. The upper limit was mainly dictated by the increasing amount of
spray needed to accomplish the task. They found that very small snails
might be blown away by the spray. They solved this problem by placing the
snails on a sheet of aluminum foil and spraying the under-surface of the
foil. Occasionally, they noted a vacuum phenomenon. When they attempted to
remove the thawed snail’s body from the shell a piece would break off in
the apical whorls due to a vacuum created there. They solved this problem
by drilling a small hole in the upper whorls to equilibrate the pressure.
Electrical- component freezing sprays come in two forms:
chlorofluorocarbon (CFC) based and CFC-free. For the protection of the
environment, we recommend that the CFC-free forms be used.

Other narcotizing methods utilizing propylene phenoxetal (Owen 1955, Owen
and Steedman 1958, Turner 1960, Rosewater 1963, 1965, Mills et al. 1997),
methanol (Smith 1996), ethanol (De Winter 1985) Sevin® (Carriker and Blake
1959), magnesium chloride (Smith 1961), amyl chlorohydrin (Smith 1961),
and freezing (Carriker and Blake 1959, Bowler et al. 1996) have also been
described. Van Eeden (1958) found that a combination of menthol and
chloral hydrate (a controlled substance) worked well on freshwater
gastropods such as Physa and Bulinus. Mueller (1972) called this
combination Gray’s Mixture, and found it useful for relaxing many classes
of marine mollusks. Papers by Runham et al. (1965), Crowell (1973),
Mueller (1972), Coney (1993), Araujo et al. (1995), Norton et al. (1996),
and Aquilina and Roberts (2000) compare multiple agents.

If you must narcotize mollusks, the best way to learn how to do this is by
apprenticing yourself to someone with experience. If this is not possible,
you should obtain the literature mentioned above and study the intricacies
of narcotization. Keep careful records and consider publishing your
results and experiences. This is a topic where more in-depth knowledge is
needed.

2.8 LITERATURE CITED

Aquilina, B. and R. Roberts. 2000. A method for inducing muscle relaxation
in the abalone, Haliotis iris. Aquaculture 190: 403-408.

Araujo, R., J. M. Remón, D. Moreno, and M. A. Ramos. 1995. Relaxing
techniques for freshwater molluscs: trials for evaluation of different
methods. Malacologia 36: 29-41.

Barker, G. M. 1981. Nembutal for narcotisation of mollusks. Veliger 24: 76.

Bowler, P. A., T. P. Johnson, and W. J. Mautz. 1996. Flashfreezing using
cold fluid: Field and laboratory methods for preventing retraction of
snails during fixation. Journal of Molluscan Studies 62: 124-126.


Carriker, M. R. and J. W. Blake. 1959. A method for full relaxation of
muricids. Nautilus 73: 16-21.

Clement, A. C. and J. N. Cather. 1957. A technic for preparing whole
mounts of veliger larvae. Biological Bulletin 113: 340.

Coney, C. C. 1993. An empirical evaluation of various techniques for
anesthetization and tissue fixation of freshwater Unionoida (Mollusca:
Bivalvia), with a brief history of experimentation in molluscan
anesthetization. Veliger 36: 413-424.

Coyer, J., D. Steller, and J. Witman. 1999. The Underwater Catalog: A
Guide to Methods in Underwater Research. Shoals Marine Laboratory, Ithaca,
New York. 151 pp.

Craze, P. G. and A. G. Barr. 2002. The use of electricalcomponent freezing
spray as a method of killing and preparing snails. Journal of Molluscan
Studies 68: 191-193.

Crowell, H. H. 1973. Preserving terrestrial slugs by freeze-drying.
Veliger 15: 254-256.


De Winter, A. J. 1985. A new rapid method for the relaxation and killing
of slugs. Basteria 49: 71-72.

Gregg, W. O. 1944. Collecting and preserving land slugs. Bulletin of the
Southern California Academy of Sciences 43: 41-43.

Heard, W. H. 1965. Comparative life histories of North American pill clams
(Sphaeriidae: Pisidium). Malacologia 2: 381-411.

Hubricht, L. 1951. The preservation of slugs. Nautilus 64: 90-91.

Meier-Brook, C. 1976. An improved relaxing technique for mollusks using
pentobarbital. Malacological Review 9: 115-117.

Mills, D., A. Tlili, and J. Norton. 1997. Large-scale anesthesia of the
Silver-Lip Pearl Oyster, Pinctada maxima Jameson. Journal of Shellfish
Research 16: 573-574.

Mueller, G. J. 1972. Field Preparation of Marine Specimens. University of
Alaska Museum, Fairbanks, Alaska. 44 pp.

Norton, J. H., M. Dashorst, T. M. Lansky, and R. J. Mayer. 1996. An
evaluation of some relaxants for use with pearl oysters. Aquaculture 144:
39-52.

Owen, G. 1955. Use of propylene phenoxetal as a relaxing agent. Nature
175: 434.

Owen, G. and H. F. Steedman. 1958. Preservation of molluscs. Proceedings
of the Malacological Society of London 33: 101-103.

Pilsbry, H. A. and E. G. Vanatta. 1898. Revision of the North American
slugs: Binneya, Hemphillia, Hesperarion, Prophysaon, and Anadenulus.
Proceedings of the Academy of Natural Sciences of Philadelphia 50:
219-261.

Rosewater, J. 1963. An effective anesthetic for giant clams and other
mollusks. Turtox News 41: 300-302. Rosewater, J. 1965. An effective
anesthetic for giant clams. Indo-Pacific Mollusca 1: 394.

Runham, N. W., K. Isarankura, and B. J. Smith. 1965. Methods for
narcotizing and anaesthetizing gastropods. Malacologia 2: 231-238.

Schander, C. and J. Hagnell. 2003. Death by drowning degrades DNA. Journal
of Molluscan Studies 69: 387-388.

Smith, A. G. 1962. Notes on cleaning mollusks. Veliger 4: 216.

Smith, D. G. 1996. A method for preparing freshwater mussels (Mollusca:
Unionoida) for anatomical study. American Malacological Bulletin 13: 125-
128.

Smith, E. H. 1961. Narcotizing and fixing opisthobranchs. Veliger 4: 76.

Turner, R. D. 1960. Some techniques for anatomical work. The American
Malacological Union Annual Report (for 1959): 6-8.

van der Schalie, H. 1953. Nembutal as a relaxing agent for mollusks.
American Midland Naturalist 50: 511-512.
.............................................................................................................

Regards,
Charlie
.................................................
Charlie Sturm
Research Associate - Section of Mollusks
Carnegie Museum of Natural History
Pittsburgh, PA, USA

Assistant Professor - Family Medicine
Fellow-American Academy of Family Practice
Fellow-Academy of Wilderness Medicine

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