Herewith we follow numerous requests by teachers to offer once more,
in detail, an experimental procedure that can be used also in classroom in order to
demonstrate waterbear revival after desiccation.
Though some of you might
think that we obiously are overdoing and behaving by far too sentimental in a
totally barbarian world:
please behave generously and put the tardigrades back on a wet moss cushion after
your experiment - no need to discuss here whether your motive should be fair play,
religious feeling, general respect against nature or simply the pleasure
of irrational, totally non-economic compassion: just do it!
The procedure is as follows: a small moss cushion, preferrably
from an old stone wall or pavement grooves, is put upside down into
a petri-dish (*) with either good quality tap water or pond-water. Demineralized
water is less ideal but will do as well as the moss sample contains the lacking minerals
and in the end everything will end up again in mineral harmony ...
In case of doubt you might as well use still mineral water, one with relatively low mineral
content - just compare the chemical analyses on the labels.
The setup is shown here .
Take care to avoid high soil contents in the moss. The petri dish with the moss
should stand still (cool environment, no sunlight) for a few hours or over night.
Afterwards you should remove the moss cushion. Most of the tardigrades from
the moss will have been fallen to the bottom of the petri dish by now.
You can examine the residue in a good dissecting microscope. An optimum
dissecting microscope has good quality optics with a magnification of
20x to 30x and wide field eyepieces. Once you have found the tardigrades
you can pick up one or two of them up by means of a standard pipette (*)
and transfer them to our recommended micro aquarium .
The ideal surrounding water quantity should allow the water to evaporate slowly,
with the micro aquarium almost totally closed, so that the residual water will vanish
during a long period, e.g. 6 to 7 hours. Quicker evaporation will kill the tardigrades
as the time will not be sufficient for the tardigrades to prepare their special
desiccation chemistry (synthesizing the trehalose sugar and positioning it
carefully around the delicate protein molecules).
Alternatively you might as well offer an extremely tiny moss leaflet as a substrate.
When the water recesses the tardigrades will look out for appropriate shelter and clinge to
the tiny moss leaf in order to have optimum survival conditions.
An optimum tardigrade dry 'tun' looks roundish, symmetrically wrinkled: