Only in rare cases you will come across pictures of water bears which show the animals in their natural environment. The reasons for this are quite clear: terrestrial tardigrades typically live in moss cushions. This material is optically dense and looks like a jungle when seen through a microscope. Hundreds, even thousands of tardigrades can hide between the plants and within the the water-filled cavities formed all over the surface area of the plants.

So, when looking at the "jungle" from outside you will perceive only a few percent of the inhabiting tardigrades at best. Even in case you should be lucky and should come across a tardigrade at once there will be problems with plant parts in the foreground. Furthermore the image quality will be very modest due to problems with focus depth as the animals normally will not be aligned in the optimal plane of focus perpendicular to the optical axis of the microscope.

Though we will not be able to study fine detail under these conditions, we will nevertheless get an impression of the natural movements of the animals on the surface of vegetable material.

Waterbear, at home, looking in your direction.
Length ca. 0,3 mm. Incident light by means of a pocket lamp.

In particular those dark moss cushions found on sunny old roofs tend to be completely opaque. But just in those places many of the interesting tardigrade "tuns" (tardigrades in the dried state) can be found. It will be difficult under those circumstances to find the tardigrades and even more difficult to study their  revival   from the dry state.

Typical homes of waterbears: dark, pin-cushion like mosses (diameter between a few cm until to about 20 cm) on a very old roof.

Never end up as a roof-cleaner and systematic tardigrade killer!

As announced in the last issue of the  Water Bear web base  our scientific team has developped a special substrate which imitates the drying behaviour of the mosses but which at the same time remains fully transparent. The problem was to design a system consisting of many small globular cells linked to each other but still allowing optical inspection. Of course the cells ideally should be similar in size to the tardigrades. Please have a look at the final result:

An artificial, transparent multi-cellular system suited for the study of the drying behaviour of the tardigrades (see text). The cell on the left side of the photograph is about 0,5 mm in height.

The artifical substrate can be cut into flat pieces by means of a razor blade (please be aware of the dangers involved!). Suited dimensions might be e.g.  1 cm x 1 cm x 2 mm. As the system by itself has no in-built nutrition for the tardigrades, only well-fed individuals should be placed into it. In any case the artificial substrate will provide enough shelter for the delicate drying process and a revival will be possible.

Echiniscus tardigrade, dried on the artifical substrate.

In order to anticipate questions by our audience concerning the exact nature of our artificial substrate (in particular where to get it and how much it will cost) we will give you a little hint now: our artificial substrate is just an artificial sponge which normally will we used by house-men for washing-up. Please keep in mind that the waterbears will prefer a new one as used ones might be smelly and soapy.

© 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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