[NHCOLL-L:4470] Preservation of Starfish and Cnidarians

[John E Simmons]

I have been compiling a bibliography on fluid preservation of biological
specimens for a book I am writing, and have listed below (in date order) the
more widely cited preservation techniques for  starfish and cnidaraians.  I
have very little personal experience with preserving invertebrates, so I
would greatly appreciate the comments on these techniques from those of you
who have experience in this area.

Concerning Joan Herrera's inquiry about starfish, the consensus in the
literature seems to be make a fluid preparation in alcohol and then
dehydrate the specimen.

Concerning Moretta Frederik's questions about preservation of cnidarians,
true fixation (=formation of crosslinks) requires use of a crosslinking
agent, which in most cases is an aldehyde, usually formaldehyde.  You can
preserve biological tissues directly in alcohol, but the chemical nature of
alcohol preservation is different (because cross-links are not formed).  If
you need a "fixed" specimen for later histological preparation, stick with
an aldehyde; if you don't, then consider alcohol preservation without true
fixation.  If you do preserve directly in alcohol, remember to change the
initial preserving solution before putting the specimens in storage, as it
will have become dilute from the dehydration of the organisms.

I would be very cautious about using isopropyl alcohol instead of ethyl
alcohol.  Isopropyl causes more shrinkage of specimens, tends to form layers
of concentration in containers, is twice as toxic as ethanol, and may
decalcify specimens if the concentration drops below 50%.

In the summaries below, 10% formaldehyde or 10% formalin refers to a
solution that is 1 part commercial formaldehyde with 9 parts water.  The
tradition in marine invertebrate preservation is to assume that the salts in
sea water buffer the formaldehyde (which they probably do).   If mixing
formaldehyde with fresh water, a buffer must be added to prevent the
solution from becoming too acidic.
John E. Simmons
Museologica
128 E. Burnside Street
Bellefonte, Pennsylvania 16823-2010
simmons.johne at gmail.com
303-681-5708
www.museologica.com
and
Adjunct Curator of Collections
Earth and Mineral Science Museum & Art Gallery
Penn State University
University Park, Pennsylvania 16802-2709


*Redenbaugh, W.A.  1895.  Preservation of some marine animals.  The American
Naturalist 29(340):399-401.*



Coelenterates:  Magnesium sulfate (saturated solution), followed by
immersion in Perenyi’s fluid, picro-sulfuric acid, or 4% formaldehyde



Ctenophores:  1 part 2% formaldehyde, 1 part Perenyi’s fluid, with NaCl to
equal the density of sea water; transfer after 30 minutes to 4% formaldehyde

* *

* *

*Wagstaffe, R. and J.H. Fidler.  1955.  The Preservation of Natural History
Specimens.  Volume One.  Invertebrates.  H.F. and G. Witherby Ltd., London,
xiii + 205 pages.*



Asteroidea:  place in water to extend feet, narcotize with crystals of
magnesium sulphate, wash rapidly, and preserve in 70% ETOH.  For dry
preservation, remove from alcohol and set aside to dry, securing the arms in
position with thread and pins



Hydrozoa:  1.  Place in sea water, add sufficient formaldehyde to make a 10%
solution.  Stir periodically over the course of several hours, then transfer
to 5% formaldehyde for storage.  2.  Narcotize by adding menthol, magnesium
sulphate or chloral hydrdate to water, then fix with corrosive acetic for 12
hours, wash, and transfer to 30% ethanol, then 50% ethanol and finally 70%
ethanol for storage

* *

* *

*Lincoln**, R.J. and J.G. Sheals.  1979.  Invertebrate Animals:  Collection
and Preservation.  British Museum (Natural History) and Cambridge University
Press, Cambridge, viii + 150 pages.*



Scyphzoa: Relax stauromedusae in solution with methanol or MS 222.  Fix in
20% buffered formaldehyde, preserve in 10% buffered formaldehyde.



* *

*Hangay, C. and M. Dingley.  1985.  Biological Museum Methods.  Volume
2.  Plants,
Invertebrates, and Techniques.  Academic Press, Sydney, Australia, xv + 323
pages.*



Coelenterates:  add formaldehyde to sea water to make 5% solution for
killing; store in 70% alcohol or Wentworth’s Solution without the sodium
hydrosulphate [80-100 ml formaldehyde, 40 g sodium acetate, 1 L of water;
then move to Solution 2, which is the same as #1 but with only 20 ml
formaldehyde]



Anemones:  aerate water before and after narcotizing with 2 drops of clove
water (or saturated solution of magnesium chloride) per liter of sea water
every hour for 4-5 hr;.  Leave overnight, then



Echinoderms:  Sprinkle magnesium sulphate or menthol crystals on the surface
of sea water bath to relax and kill, thentransfer directly from sea water to
70% ETOH or 10% formalin and sea water



Starfish:  place in 20% ethanol until ambulacral feet are extended, then
place in 70% ETOH.  May also be relaxed in soda water, 1% 2-phenoxyethanol,
or nicotine water.  For a dry specimen, preserve in alcohol first, then
dehydrate
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