The Krka National Park in Croatia - a tardigrade home (I)

The Croation Krka National Park is located in the Mediterranean area, between the towns of Split and Zadar. And it is being visited by many tourists. But, an estimated 99.9 % of those toustists will not be aware of the fact that water worlds are at the same time tardigrades' worlds.

For your utmost pleasure in the park it might be advisable to escape from the central stone staircases as soon as possible. Once you will have forgotten their tremendous ugliness you will notice many tiny pathways guiding you through a world of beautiful form and colour. So you should actually plan to go there whenever possible on one of you travel routes. Our photographs below might serve as a humble incentive to do so:

Visual water impression from the Krka National Park, Croatia. In the background the central main waterfall is visible. The overall dramatic appearance is simply due to higher water levels, no tsunami catastrophe.

As a tardigrade enthusiast we are used to look out for typical tardigrade habitats like the one shown below: Calcite containing sun-lit walls, close to flowing water, a perfectly ideal situation. This one was half way up of the Krka waterfall slope:

Some cement-guided water, ornamented by moss.

So we felt compelled to take one of our very modest moss samples (remember, we were amidst of a National Park!). At home the moss was put in water and screened as usual.

In some cases the existence of tardigrades becomes obvious because of the presence of eggs or empty cuticulae after molting. In this case the first traces were different. We came across some typical tardigrade "garbage bags" like the ones shown below. Just keep in mind that the tardigrade world is free of toilets like the rest of nature. So it is a wise idea to keep the digestion remains in a sort of bag which will not pollute the environment. In the end the mess will be cleaned up by bacteria and vanish after some time. Thus tardigrades are perfect neighbours within the moss scenario, keeping their environment as clean as possible:

Tardigrade "deposit". When squeezing softly the characteristic material properties become more apparent.

And yes, the tardigrades themselves must be present, too. We are going to show one of them here:

Krka National Park, Echiniscus sp. tardigrade, body length ca. 0.2 mm.

Krka National Park, Echiniscus sp. tardigrade, different focus level, body length ca. 0.2 mm.

Those among you who love exact terminology and species determination are cordially invited to count the thorns and filaments in the image above (possibly filaments in positions "A" and "D"?) and to draw their own conclusions. We think that most of those Echiniscus species are so closely related that it is not worth while to tell them apart. But of course, this is up to you to decide. Just proceed as you like to!

© 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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