[NHCOLL-L:5236] Re: Preserving a dead shark

Tue Feb 1 03:59:45 EST 2011

Hi all,

just back from Berlin, sorry for my late reply.

Generally and compared to bony fishes there are rarely any problems with 
tissue damages in cartilaginous fishes. This may be different in single 
species, but I think one possible explanation might be the high urea 
content of the cells which might prevent them from deterioration (e.g. 
freshwater stingrays from the Amazon need as much attention as bony 
fishes, especially as they produce a thick mucous layer after thawing 
which obviously lowers diffusion and prevents penetration of formaldehyde).

Actually, we have a small formalin fixed marine shark (approx. 15 cm) in 
a water bath for over two month to wash out any residual formaldehyde as 
we need this specific specimen for sequencing. Even though continuously 
flushing this tiny fellow with cold tap water for that long, the 
specimen is in perfect condition (not smelly, no decomposing tissues, 
not turning slimy etc.).

It's hard to pinpoint, but to me it seems that (marine) cartilaginous 
fishes in general behave somewhat different during fixation. E.g. a 
large shark collection we received during the 1970ies, which was 
initially carried frozen in large drums from a larger research vessel 
after landing in Australia. Being transported for considerable time 
prior to fixation, the catch started thawing, decomposed under the hot 
sun and subsequently became quite smelly. Because being already quite a 
mess, initial fixing was done with a mixture of benzine and formaldehyde 
(...). Stored in drums for more then 25 years here in our museum, 
tissues picked from these oily and (still) quite smelly specimens 
produced at least a 300 base pair DNA after extraction (following a 
special routine for formaldehyde preserved tissues) ... For sure, bony 
fishes would't have survived such a treatment. As already hypothesised, 
a possible reason might be the urea content within the cells, but this 
rather my mere guess then a well supported fact.

All the best
Dirk

Am 27.01.2011 22:21, schrieb simmons.johne at gmail.com:
> DIrk and SImon
> My concern with thawing the shark prior to preservation is the amount of tissue damage that occurs during freezing and thawing which is why I reccomend thawing in fomaldehyde. Your comments on this will be appreciated.
> John
>
> ----------
> Sent from the Verizon network using Mobile Email
>
> ------Original Message------
> From: Dirk Neumann<Dirk.Neumann at zsm.mwn.de>
> To:<Couteaufin at aol.com>,<sej139 at yahoo.com>
> Cc:<NHCOLL-L at lists.yale.edu>
> Date: Thu, Jan 27, 8:43 AM +0100
> Subject: [NHCOLL-L:5211] Re: Preserving a dead shark
>
> Hi Steven, Simon,
>
> from experiences with preservation of our 200 something Etmopterid
> sharks I would adjust Simon's procedure as follows:
>
> Thaw the shark under cold water (don't use hot water)
> Pin the fins prior to formalin fixation and try to get the shark in a
> somehow natural shape (elsewise you will fix the specimen as bended as
> retrieved from the freezer).
> Take the tissue sample in advance (immediately after thawing), best take
> muscular tissue from inside of the body cavity by cutting the abdomen IN
> FRONT of the anus
> Cut the body cavity to allow influx of formaldehyde solution into the
> belly; this works much better then injections and especially allows
> escape of the oil emerging from the liver which elsewise you will have
> an awful smelly preservation issue for years (see Simon Moore's comments
> on this, you may have a pH-issue with breaking fatty acids).
> Consider to wash the specimen with a bit detergent after recovery from
> fixation to avoid too much oil in the alcohol.
> Sharks are rather easy to preserve and not as sensitive as most bony fishes.
>
> Hope this helps
>
> All the best
> Dirk
>
>
> Am 27.01.2011 00:22, schrieb Couteaufin at aol.com:
>    
>> Hi Steven,
>> You shark - what you proposed re the formalin sounds fine to me.  Once
>> fully thawed, inject it with 10% formalin (3.76% formaldehyde) until
>> it just starts to swell ever-so slightly or the fluid runs out again.
>> Make sure that you inject the brain area, the area round the liver and
>> the pelvic cavity too.
>> You can then preserve it (after a few days) in 5% formalin, alcohol
>> (gradually up a ladder of 20% stages) or whatever preservative seems
>> easiest.  If you want DNA then don't leave it in formalin for more
>> than 5 days and transfer to alcohol.  You will get some lipid (as
>> yellow-brown globules) leaching in time from the liver in particular,
>> as formalin will only preserve lipid.  Don't worry if the fluid is
>> still clear but if it turns at all murky or dark brown, check the pH
>> and change the fluid anyway for fresh.
>> Have fun and check out the website below, if time permits.!
>> With all good wishes, Simon
>>
>> Simon Moore MIScT, FLS, ACR,
>> Conservator of Natural Sciences,
>> 20 Newbury Street,
>> Whitchurch RG28 7DN.
>> www.natural-history-conservation.com
>> <http://www.natural-history-conservation.com/>
>>
>> http://uk.linkedin.com/in/naturalsciencespecimenconserve
>> In a message dated 26/01/2011 22:41:20 GMT Standard Time,
>> sej139 at yahoo.com writes:
>>
>>      Hi everyone, sorry to bother the list with something that isn't
>>      really all that
>>      paleo related, but I was wondering if someone could help me out. I
>>      recently got
>>      a roughly 1 foot long baby shark. Since it is so young, I would
>>      like to preserve
>>
>>
>>
>>      it. It is currently frozen in a block of ice until I can figure
>>      out what to do
>>      with it. Since I would like to preserve it, I was wondering what
>>      the best and/or
>>
>>
>>
>>      easiest way to do that might be. I have been leaning toward
>>      getting some
>>      formaldehyde or formalin, injecting some into it and preserving it
>>      in a jar with
>>
>>
>>
>>      the rest. If that is best, how much should I inject into it.
>>
>>      Thanks for any help I receive,
>>                ~Steven
>>
>>      ~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
>>      Steven E. Jasinski
>>      Paleontological and Research Assistant
>>      State Museum of Pennsylvania
>>
>>
>>      Graduate Studies
>>      Department of Biology
>>      East Tennessee State University
>>
>>
>>      Phone: (717)586-9835
>>
>>
>>
>>
>>
>>      
>
>    

-- 
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