Eternal sleep? - a dry state with expiry date (III)

In the   last issue  of the Water Bear web base we had reanimated - very few - tardigrades from a moss cushion that had been kept perfectly dry for more than four years. And we had announced to look out for some moss samples which had been dry even for decades!

The antiquarian's internet platform ZVAB (www.zvab.com) is offering millions of books - but not only books. From time to time you will notice that a few other 'cuckoo' items are smuggled in as well. This might be annoying in some cases but could turn out as a lucky coincidence as well.
One day we stumbled across such a 'false' book of particular interest to us. It was offered as a "Moss Herbarium by Frater Erhard, Eichstätt (Germany), 1925" at a rather modest price. Our elder readers will be aware of those long-gone hobbyists who spent days and weeks collecting plants outside, later carefully drying them between sheets of paper, then labeling and storing them for personal study and later reference. Many private herbaria are now considered to be useless and are sold at flea markets. In fact very few people actually care about those dust-covered remains of past periods. Museums suffer from ample 19th century herbaria collections with thousands of items which tend to yellow, to dissolve into hopeless paper fragment and which even attract all kinds of nasty avid microzoological paper shredding individuals. Moreover, today's young people as a rule will consider those herbarium activities as an hopelessly outdated, old-fashioned behaviour.

"You see, when I am looking out for an image of a plant, I will simply use an internet search engine and there will be thousands of pictures ...".

Yes, agreed, they will find their images, but there will be some severe loss of inherent information as well: just keep in mind that those old-fashioned herbaria do preserve the plants themselves, in their material entity - and possibly some tardigrades contained within the yellow paper as well?

Our antiquarian's herbarium is rather modest, like a box of cigarettes in size. It contains a 2 cm stack of 38 paper sheets, each one with a moss plant sample, neatly sticked to the center of the sheet and labelled with funny old German names like "Spitzblättriges Farnmoos" and in parallel with the respective Latin binary scientific designation as well (in this case "Mnium cuspidatum").

An overview of the moss herbarium prepared by Frater Erhard in 1925, dedicated to his father, kept in a robust self-made brown paper envelope. 38 specimens on 38 sheets of paper plus a cover title page.

Cover page of the moss herbarium by Frater Erhard

A preliminary wetting test with one of the big Sphagnum  samples led to an impressive result immediately. Much quicker than estimated in our boldest dreams we came across an ancient egg of the tardigrade Macrobiotus hufelandi !

Tardigrade egg (Macrobiotus hufelandi) in one of the Sphagnum samples of the herbarium. Egg diameter ca.  0.1 mm.

Same egg as above, detail view.

Nevertheless it is obvious that this is by no means a revivable egg but a "really dead" egg. In contrast to fresh eggs by M. hufelandi  the inner protein content is coagulated. The structure reminds of one of those breakfast eggs that are no more perfectly fresh, revealing concentrical layering and striae.

After this partial success we were really keen to continue with the comparatively small sample of Grimmia pulvinata , a moss species well known to exist on favourite tardigrade places like sun-lit walls and old roofs. After watering a single moss plant stem revealed several traces of former inhabitants and surroundings: we did find pollen grains, dry rotifers and, in the end - a tardigrade!

Grimmia pulvinata sample from the herbarium.

Grimmia pulvinata sample from the herbarium.
Close-up view.

Pollen grain from the Grimmia pulvinata moss sample.

Rotifer in dry state from the Grimmia pulvinata moss sample. Outer geometry in perfect order but not revivable after watering.

And, last but not least, the tardigrade within the Grimmia pulvinata moss sample, no more revivable as well  :-(

Detail of the previous view. Protein coagulation within the tardigrade body cavity.

Of course it is a pity that we did find only dead remains within the herbarium samples. But we are not surprised, as we did learn already in the last issue that a tardigrade revival after four years can be regarded as a rare event.
As a consequence a revival after more than 80 years appears to be highly improbable. But, who knows, unter favourable conditions ... perhaps ... ?
On the other hand we are now greatly appreciating those collectors' activities of past times which preserved the complete moss ecoystem within their modest sheets of paper thus providing an optimal basis for our studies.

© Text, images and video clips by  Martin Mach  (webmaster@baertierchen.de).
Water Bear web base is a licensed and revised version of the German language monthly magazine  Bärtierchen-Journal . Style and grammar amendments by native speakers are warmly welcomed.

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