A Florarctus tardigrade from Croatia (II)

After some delay - sorry - we are going to present some face-to-face views of the Florarctus tardigrade from Croatia.
As you will be able to imagine, the most easy-going images of tardigrade are those taken in top view. But from time to time, in lucky moments, the tardigrades seem to look at you, the microscopist!

Florarctus sp., frontal view (I)

Florarctus sp., frontal view (II)

This pair of images above is quite well suited to illustrate the movement strategy of the tardigrades between the sand grains (within the so-called interstitial system). The tardigrade uses its hind pair of feet to keep contact with the base sand grain, stretching out and slightly curving its body in order to seek contact with new environments (typically the neighbouring saind grains). In order to move forward it has to shovel back some water volume with its front legs. Of course it is of tremendous importance not to get lost in the holes and potential water drifts between the sand grains but instead to reach the next grain safely. Transferred to human dimensions the sand grains can be quite large, e.g. 5 meters! So the tardigrade is some kind of marine alpinist crossing between terribly roundish rocks (a situation which has to be considered as one of the more complicated alpine difficulty grades). The best strategy is of course to keep a strong contact to the base grain until the target grain is in safe reach.

In contrary to Batillipes who is able to clinge to glass including the inside of pipette glass (!) Florarctus is not able to hold tightly on slides and within pipettes, so it can be transferred safely from one dish to the other without losing it.

As always with marine tardigrades the overall body size is modest and the contrast of the inner organs poor. So it is rather difficult to study the Florarctus anatomy in normal microcopic brightfield illumination. Nevertheless the image pair above is able to show a globular bright area (the pharynx). Furthermore it is possible to discern the bucchal tube in the central axis of the head region.

The next image below is representing a female which we were able to recover from our micro aquarium, two weeks after or return from Croatia. It was crawling on the very top layer of the sand and we were able to find it due to its strongly contrasting stomach content.

Florarctus sp. female. Total view, body length ca. 0.1 mm. Please note the elegant synchroneous movement of the front legs (which remind of arms in this situation). Moreover you will be able to see the grey egg on the left side of the hind body.

Don't worry, we did put it back into the micro aquarium and hope that the egg did develop well after our photography treatment (photography in cold light, of course!)

© 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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