A Batillipes sp. tardigrade from Pag island (I)

There are moments when we would like to create some kind of new magazine, e.g. one entitled "Bizarre Worlds". We could use it in order to present our non-tardigrade nature photographs, some of which seem to be in need of discussion and understanding:

"Three friends" - a strange grasshopper group, as seen in Croatia.

In the previous magazine we had introduced a special sampling device for deep water scenarios like e.g. harbour basins where swimming and diving is prohibited. This time we are going to discuss a sample taken by means of this device from the grounds of the harbour of the island of Pag (Croatia). As explained previously we have been encountering high tardigrade population densities in shallow water and at the tidal shoreline. On the other hand we are aware that some early descriptions of marine tardigrades are base upon deep water sampling.
E.g. professor Ferdinand Richters reported the first finding of Batillipes tardigrades from deeper water - just a few tardigrades found after a fortnight (!) of microscopic searching. So we were not surprised that a first screening of the sample of Pag harbour didn't reveal anything worth mentioning. One way to cope with this situtation might be the chemical attack of big sand samples (we don't like the idea) or, alternatively, a more relaxed approach: Still looking out for tardigrades but besides having plenty of time to enjoy the presence of other animals and algae within our sand samples.

Foraminifera from sand of Pag island, measuring ca. 1 mm. Dark field illumination.

Though a foraminifer does look quite appealing some of you will even more appreciate those diatoms which might appear as isolated individuums or in small groups. The beauty is becoming particularily apparent in the moment when we fail to handle it in an appropriate manner. A classic accident - the diatom shell cracking under cover glass pressure:

Diatom from the Pag sand sample, ca. 0.2 mm in diameter.

The same diatom - alas - quickly cracked unter coverglass pressure. Details of the scale splinters, reminding of cracked ice on cold water puddles.

In the long run our investigative patience will pay off. As a rule there will be a thrilling moment with a characteristically shivering sand grain. You might be able to isolate the sand grain and the tardigrade behind it - with a result as shown in the following photograph:

Tardigrade from the Pag sand sample, as seen under the dissecting microscope.
Image width ca. 2 mm.

In order to collect further information we are going to transfer our tardigrade to the regular compound microscope:

Tardigrade from the Pag sand sample, with micrometer ruler.
Body length ca. 190 µm.

A first portrait at slightly higher magnification is helping in order to reveal the genus: the toe lobes tell us that this is a Batillipes tardigrade.

Tardigrade from Pag island, total view.

The anatomy will be subject of the next issue of our magazine - stay tuned!

© 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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