A view of the city of Munich - slightly different (IV)

As already reported in the last issue, the pavement moss from the city of Munich did contain many tardigrades. But most of them seemed to belong to one genus only, namely Macrobiotus. For Macrobiotus taxonomy eggs can be extremely useful, but in this case they appeared to be absent. After hours and hours of screening we finally came across a few tardigrade eggs. And they look like those of the species Macrobiotus hufelandi:

Tardigrade egg from Munich pavement moss. The surface area of the egg is completely covered by so-called protrusions the geometry of which is described as "egg-cup shape" in literature. Those protrusions are considered to be characteristic for the best known species within the Macrobious genus, Macrobiotus hufelandi. Possibly our readers will remember that the inner structure of the egg shown corresponds to an early development stage (multi-cell stage but still undifferentiated), the so-called morula stage (looking like some kind a berry). Diameter of the egg: ca. 60 µm.

Perhaps you might wonder about the difference between rural and city tardigrade living conditions? And perhaps you will remember one of those children's book where two mice are discussing the advantages and disadvantages of their living areas, city vs countryside? Possibly in both areas there is a constant danger for the tardigrades to be killed by the human species which might be called the eager homo pavement cleaner. In many European countries you will come across people who think that every tiny moss cushion is a representation of the devil on earth. As a consequence they are performing regular steam-cleaning on every pavement stone around their houses.

But let's return to our comparison: There is no doubt that the city tardigrades are surrounded by human garbage which can be found in many city moss samples. In the eyes of a tardigrade even small garbage particles will look like elephants. Many human activities are constantly setting free tiny particles which cannot be noticed by us but which will be noticed by the tardigrades. Parallel worlds with only little connection in general but with a kind of garbage bridge!

Artificial resin particle from Munich pavement moss, ca. 1/10 of a millimeter in size.

Pigmented particle from Munich pavement moss, about the same size als above, ca. 1/10 of a millimeter in size. Most probably this one is a flake made up of white marker paint from parking area lines. Those lines suffer from constant abrasion and are not tremendously durable.

And yes, all those numerous dog hairs found within those city moss samples can be regarded as anthropogene as well (no image). Those hairs have a sad tendency to bind with the moss and to stay kept in it. Nevertheless the tardigrades appear to be able to cope with all the mixed garbage of the city environment. They just have to find some tiny piece of "city green" and cling to it. It will serve them as a home, nutrition source and shelter. There are tiny cavities which can be found and used as tardigrade homes, as shown below:

Tardigrade on (and in!) a tiny vegetable particle from Munich pavement moss.

© 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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