Be warned! Christmas is
quite close, there is no way out.
In order to cope with the urgent and increasingly exotic gift demands of your environment you might consider
an elegant escape: the brand new December issue of the Swiss nature magazine "La Salamandre" is
dedicated especially to tardigrades. Feel free to use the direct order link now ("Commander ce numéro").
You will be able to browse through a preview version of the tardigrade issue on-line as well.
Maritime Tardigrades (II)
"How to search and, more important, how to actually find them?" -
these will be the vital questions once you are going to focus your interest
on marine and maritime tardigrades.
Of course, all of us have a rough idea about the object (some tiny animal
crawling about on eight legs ...) and a rough idea where to look for it.
For a start any beach along the borderlines of our continents or marine
islands will do. Methodology needs to be considered, too.
Rewarding objects of desire? Where to find? How to approach?
Before starting off to the seaside,
we suggest to have a glance at the respective scientific literature.
As we had mentioned in the last magazine, e.g. the French zoology professor
Felix Dujardin obviously had found just a single maritime tardigrade individuum
all over his life. Also the German professor Ferdinand Richters needed
extensive microscope sample screening time ("weeks") in order to collect
enough specimens for his Batillipes mirus publication.
So it is evident that Pennak found only two tardigrades per cm3 of sand.
Sand beach at the French Atlantic Coast, north of Royan with many, many tardigrades, distributed among even more sand grains ...
Okay, we have been digging at a few beaches. The crime scene looks terribly at the moment but it will perfectly vanish after the next high tide:
Tardigrade digging at the French Atlantic Coast, south of Royan.
Of course we have tried some of those many collecting and enriching recipees from the literature: filtering, immersion and decanting, driving out the tardigrades by means of melting sea water ice, by magnesium chloride solution etc. but in the end we came to the conclusion that the simple collection technique by means of shoveling sand with a plastic film container is the best suited method for the beginner.
In our opinion the very best tool for maritime
tardigrade collecting: a film container (you will remember, we used those
in the analogue photography era).
Even when screening those samples with a very good dissecting microscope at 30x magnification the tardigrades are difficult to find. The following photomicrograph is intended to demonstrate the size relation with respect to fine sand grains:
The micrometer scale (top left) measures 0.25 mm, so the tardigrade body length is well below 0.1 mm! Note that even fine sand grains (appearing black in this case) look like rocks when compared to the tardigrade body size.
How did we notice our first maritime tardigrades? First of all because of those magically moving sand grains like the white one below:
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Don't worry, better videos will follow in the upcoming issues of our magazine. This issue was just intended to point out that the study of terrestrian tardigrades definitely will be more easy-going for the beginner.
© Text, images and video clips by
Martin Mach (email@example.com).