A pathway to the understanding of mosses?

Well, there are some leisure time activities with dwindling public interest, like e.g. the collection of postal stamps. Possibly scholarly piano playing, too. But on top of the leisure time activity looser list we will most probably find the collection of dried plants and the taxonomic determination of mosses. So when maximising minimum public interest (thorough taxonomic determination of disesteemed dried mosses) mosses might have good chances to come out as the winners. Moss taxonomy is actually a very rare leisure time activity nowadays. Frankly, how many of your friends are actually spending their internet free and work free hours on the drying and studying of mosses? On the other hand it must be admitted that many of those mosses look beautifully in the macroscopic and microscopic view. And they make up the classical homes of terrestric tardigrades. So we cannot ignore them.

The classical tardigrade habitat - a Grimmia pulvinata moss cushion in the dry state. Top view.

The German species names simply cannot be translated but we think that also the foreign reader will feel the crazy complications which are embedded in the German word-chain species names like e.g.:

- Streifenfarnähnliches Schiefmundmoos (Plagiochila asplenioides)
- Kriechendes Schuppenzweigmoos (Lepidozia reptans)
- Breitgedrücktes Kratzeisenmoos (Radula complanata)
- Tamariskenblättriges Sackmoos (Frullania tamarisci)
- Ausgerandetes Geldbeutelmoos (Marsupella emarginata)
- Zungenförmiges Jungermannsmoos (Jungermania lanceolata)
- Zweizipfeliges Kopfsproßmoos (Cephalozia bicuspidata)
- Aufgeblasenes Nacktkelchmoos (Gymnocolea inflata)

There exist at least 12,000 valid moss species in Europe alone (without liverworths, based on an estimation by [Weymar 1958]). So anyone with plenty of time, anyone without a TV or a smartphone can spend decades on the study and the memorizing of those moss species. Most probably you, dear reader, will be among those who don't have the nerve to patiently reach this goal. But, as far as the tardigrades are concerned, we can use a cheat and confine our discussion to a more general (and superficial, sorry) view of the moss properties.

The cross section trough a typical moss section as shown below makes clear that mosses are hard core humidity reservoirs: their hemisperic surface geometry is providing a sound geometrical basis for a minimum of evoporation loss. Moreover, the grey glass hair tips are creating some kind of damp jungle where evaporating humidity is kept back and is serving as an insulation layer against desiccation. On the other hand the mosses are able to absorb huge amounts of water within seconds. So the mosses are true desert pioneers, equipped to settle on rock and stone without any soil substrate. They do not rely on roots - which would not help a lot on the rock surface but instead they are maximizing the use of rain water and even air-borne nutrition.

Grimmia pulvinata moss cushion. Cross section view.

According to the evolution theory of tardgrades all water bears emerged from the oceans. So the mosses and their water reservoirs might be regarded as some kind of "ocean reserve", helping the early tardigrade pioneers to settle outside the oceans. Furthermore the mosses are serving as sources of nutrition for the tardigrades. We will present some of the hidden delicacies in the upcoming issues.

Literature

Weymar, Herbert: Buch der Moose. p. 12. Radebeul 1958 (in German language).

© 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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