[Nhcoll-l] Moon jellyfish in liquid

[Simon Moore]

Hi Joosep,

To keep jellies transparent / translucent, you need to keep them in neutral pH 5% formalin (2% formaldehyde).  This fluid is less hazardous than the full fixation strength 10% and has the advantage of keeping the specimens as natural-looking  as possible.  Alcoholic preservative swill render them opaque and can cause tissue shrivelling due to osmotic pressure changes.  If you dilute alcohol in situ with the specimen present then the alcohol will generate tiny air bubbles that will find their way into the specimen and cause the tentacles to curve upwards!  This will also apply if you add any other binary azeotrope fluid such as glycerine and the specimen will slowly adapt to the changed specific gravity and will start to sink again over time.
If you wish the specimens to hang in the centre of the fluid, I have used nylon monofilament with a small disc of transparent acetate plastic sewn through the centre of the umbrella from the ventral side and then attached to a small plain glass float (like you might hang from a Christmas tree).

I do have pics of these but you would need to contact me off list.

With all good wishes, Simon

Simon Moore MIScT, RSci, FLS, ACR
Conservator of Natural Sciences and Cutlery Historian.

www.natural-history-conservation.com


> On 17 Aug 2023, at 13:37, Callomon,Paul <prc44 at drexel.edu> wrote:
> 
> We have a number of jellyfish in 70-80% ethanol that float nicely and have retained retain their shape. It seems to depend on the species, but Nettles (Chrysaora) and Cannonball Jellyfish (Stomolophus) at least are OK. If the specimens float or sink a bit too much, you can adjust the specific gravity of the fluid to some extent by adding water or alcohol until they behave.
>  Paul Callomon
> Collection Manager, Malacology and General InvertebratesAcademy of Natural Sciences of Drexel University
> 1900 Benjamin Franklin Parkway, Philadelphia PA 19103-1195, USA
> prc44 at drexel.edu Tel 215-405-5096 - Fax 215-299-1170
>  From: Nhcoll-l <nhcoll-l-bounces at mailman.yale.edu> On Behalf Of Joosep Sarapuu
> Sent: Thursday, August 17, 2023 8:32 AM
> To: NHCOLL-new <nhcoll-l at mailman.yale.edu>
> Subject: [Nhcoll-l] Moon jellyfish in liquid
>  External.
> Dear all,
>  We have an exhibition coming and we would like to show there a moon jellyfish (Aurelia aurita) in a liquid. Do someone has any idea what liquid it should be that keeps the specimen „open“ as in sea water. I have heard that EtOH will make jellyfish to contract. Glycerin and formalin might work in this case? What might be the ratio?
>   Sincerely,
> Joosep Sarapuu
> Estonian Museum of Natural History
>      _______________________________________________
> Nhcoll-l mailing list
> Nhcoll-l at mailman.yale.edu
> https://mailman.yale.edu/mailman/listinfo/nhcoll-l
> 
> _______________________________________________
> NHCOLL-L is brought to you by the Society for the Preservation of
> Natural History Collections (SPNHC), an international society whose
> mission is to improve the preservation, conservation and management of
> natural history collections to ensure their continuing value to
> society. See http://www.spnhc.org for membership information.
> Advertising on NH-COLL-L is inappropriate.