Sunny environment

Some miles south from a Bavarian lake called "Tegernsee" we find mid-range alpine regions with local names like Moni-Alm, Suttenalm und Firstalm (with the term "Alm" indicating mountain pastures). The typical height of those places above sea level will be about 800m to 1200m or higher. This kind of location might already be high enough to serve as a potential habitat for those strongly yellow Richtersius coronifer water bears. At least we had hoped so when coming across a small rock with green moss close to the "Firstalm" signpost shown below.

Signpost at about 1,000 m elevation directing towards various mid-range height sites.

From this little rock fragment close to the signpost we removed a small sample of ultra-dry black moss.

Back home, after watering the sample, we were slightly disappointed. At first sight, everything looked just the same as in urban central Munich: Some red Echiniscus tardigrades and some Eutardigrades, the latter probably belonging zu the ubiquituous species Macrobiotus hufelandi (sensu lato), apparently nothing special. The photomicrograph below is depicting a head with macroplacoids in the typical  M. hufelandi arrangement, plus the usual broad curved stylets, the wide bucchal tube and the fine stylet springs in perpendicular orientation on both sides of the tube.

"Alm" tardigrade Macrobiotus hufelandi (sensu lato), Detail view of the head region with stylets and typical macroplacoids. Image width ca. 0.1 mm.

No exotic tardigrades ... disappointment? Yes, a little bit. But there is still one thing to mention: The famous tardiologist Ernst Marcus confirms that mountain inhabiting tardigrades normally will show stronger pigmentation than their relatives at sea level. And this is actually what we found when looking closer at the sample. Starting with incident light we are studying the body mass of a tardigrade crawling within the moss jungle:

"Alm" tardigrade Macrobiotus hufelandi (sensu lato), seen from behind, plunging into a moss plant cavity. Please note the intensively brown pigment patches on the snowwhite body volume.
Incident light.

In transmitted light it becomes clear that the pigmentation distribution is heterogeneous and moreover slightly patchy.

"Alm" tardigrade Macrobiotus hufelandi showing surface regions with strong pigmentation. Transmitted light, image width ca. 250 µm.

"Alm" tardigrade Macrobiotus hufelandi, same as before, stronger magnification. Transmitted light, image width ca. 0.1 mm.

Freckles? UV damage? Signs of age? Just a coincidence? Up to you to decide!

Literature

Ernst Marcus: Tardigrada. p. 231. Akademische Verlagsgesellschaft, Leipzig 1929.

© 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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