10 October 2005

Gastropods for posterity


A reader in a comment to yesterday's post on snail shells in museum collections, wondered if the snails' bodies can also be preserved. Why, of course, we do it all the time.

We didn't visit the alcohol collections last Friday, so today's pictures are from my collection. Although I don't like killing them, I do have a large collection of pickled snails and slugs in my basement (yes, it's all in the name of science).

The preservative of choice is 70% ethyl alcohol (ethanol), the remainder being water. I add a little bit of glycerol to my alcohol solutions to prevent the specimens from drying out should the alcohol evaporate (glycerol absorbs water and doesn't dry). To preserve their DNA, the specimens are kept in 95% ethyl alcohol.

Isopropyl alcohol (rubbing alcohol) would also preserve soft tissues, but it tends to make snails' bodies too hard for dissection. Tim Pearce says ethanol concentrations higher than about 70% also harden tissues, but it is a tradeoff with preserving DNA.

And this one is for Celeste, to show her that the little jars she's been saving for me are indeed being put to good use. This jar once held red raspberry preserves.


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