By Jack Ashby, on 4 August 2014
Museums are full of mysteries (particularly when you are as cursed with historically challenging documentation, as many university museums are). For example, why do we have a plum in a jar? Why does our dugong only have seven neck vertebrae (it is one of the few mammal species that should have eight)? Why don’t we have a wolf, one of the world’s most widespread mammals? Who ate our Galapagos tortoise? Why do we only have the heart and rectum of a dwarf cassowary? Why is scary monkey (pictured) so scary?
Not to mention, why did we put all those moles in that jar?
After ten years of working here, I am confident that there is no greater mystery in the Grant Museum than this one: why would you stick a battery in a dead animal?
This week’s Specimen of the Week is…
**The Battery-Powered Opossum**
1) To quote directly from the conservation report:
Could not distinguish fluid type; odour suggests the fluid is not formalin, the fluid was also not registered as alcohol by the fluid density meter.
Specimen appears to have a rusty yellow coloured tint and seems to be dyed in some way. Yellow sediment is present in the fur of the specimen and has also settled at the bottom of the container.
Yellow coloured growth from stomach area transpired to be wads of cotton wool (orange tinted) which had been stuffed inside the specimen. On removal, a D-type Duracell battery was removed from the body cavity (organs seem to be removed).
The specimen was washed thoroughly in distilled water to remove all traces of rusty coloured crud. The fur was brushed
Specimen was transferred back to original glass container, the ground glass lid replaced by a round glass plate. The unknow fluid was replaced with 80% IMS. New labels inserted, lid sealed with Dow Corning sealent. Painted around top with black acrylic paint
2) So please help us solve this mystery – why was there a D-cell battery inside this preserved opossum? I have two theories: a) it was an experiment into the evolution of the Duracell bunny. b) something terrible and Frankensteiny, only using a much lower voltage (1.5v vs. whatever is in lightning). Suggestions in the comments box please.
3) You may ask why we don’t have any records of this electrical insertion, as obviously it can’t have happened that long ago given that the presence Duracell D-cell batteries gives a maximum age to the specimen’s preparation (if not its original field collection). The reason we are so clueless is that this wasn’t always a Grant Museum opossum, or even a UCL opossum.
The one thing we do know about it is the small label “5ap”. This specimen number identifies it as one of a huge number of specimens which came to the Grant Museum in the 1980s from Imperial College London when there zoological collection was closed and absorbed by us. Unfortunately the records or catalogues which could have told us more about “5ap” and the rest of the Imperial fluid collection were never located in South Kensington at the time of the transfer, or since.
4) To tell you something more zoological about the specimen, opossums are American marsupials. The more famous marsupials (outside of the Americas, at least) live in Australia and New Guinea, but they only account for about two thirds of marsupial species. The rest live in Central and South America, with one species – the Virginia opossum – having wandered into North America. Marsupials are mammals which give birth after a short gestation to highly under-developed young, which then undertake a long period of development by suckling on a teat (often in a pouch, but not always). By contrast the more common (and if you ask me, less interesting) way of being a mammal involves a long period of development in the womb, followed by a relatively short period on the teat, like in humans.
5) There are 92 species and 19 genera in the opossum family, Didelphidae (making up by far the bulk of American marsupials which numbers 99 in total). You could only fit a watch battery inside the smallest species – the mouse opossums, while those capable of accommodating a D-cell battery are at the top end of the opossum size scale.*
Jack Ashby is the Manager of the Grant Museum of Zoology.
*The Grant Museum does not endorse the insertion of batteries, or any other objects, into opossums.