We do report with proud that one of our favourite printed magazines,
mare (a fine magazine devoted to ocean topics),
finally decided to use one of our tardigrade images. In addition mare
journalist Ute Schmidt created a well fitting text in lucid style,
which was by no means copied or simply stolen from our internet pages (as some tv people
tend to do ...).
This article can be found in mare, issue 67, April/May 2008.
By the way, mare always is worth a glance or two - and please believe us,
we didn't receive any $$$ for this compliment!
Index of mare #67. Please understand
that we cannot present the text of this article here for copyright reasons.
"Size matters!" - in search for the Locus typicus of Batillipes mirus
Small, smaller, tardigrade - hunting water bears remains a challenging task.
As a small helper we are going to present a few images - animated GIFs,
which are intended to explain how sand grain screening under the dissection
microscope looks like. First of all, even in single layer sand grain coverage
there is only a 50% chance to find the tardigrade as it might sit above but as well hide
below the sand grains. But still, even below the sand grain it might remain slightly
visible like this Batillipes tardigrade:
Batillipes tardigrade moving
under a sand grain of about 1 mm diameter. Only due to the colour of its
stomach content it is gaining a little bit of contrast. Otherwise it would be
perfectly transparent and invisible.
Furthermore, you should be aware of the fact that
Batillipes does note any movement of the petri dish. A moving
petri dish is roughly equivalent to a marine water current. As a consequence
the tardigrade will stop moving in order to bring all its 48 adhesive disks
in safe contact with the sand grain surface. It will wait a little bit
until the felt water current ceases and only then re-start with its movements.
When moving, the tardigrade is well able to shake huge sand grains. The size relation
between the tardigrade and the sand grain as shown below is equivalent to a
man moving a rock with a diameter of 10 meters (!).
A Batillipes tardigrade
is shaking a 1 mm sand grain. Four images' GIF sequence. The power dwarf
can be seen for a fraction of a second, top left (position 12 o'clock).
How can we be sure at this low resolution
that the moving spot is actually a tardigrade? The head movements are quite
characteristic, just remember that Batillipes is blind and that it has
to sense the limits of its environment by means of its head movements:
A Batillipes tardigrade.
The head is directed downwards in the image. Characteristic head movement.
The hind legs are difficult to see in this sequence but clearly present (though not moving).
When trying to reach higher magnifications
under the dissecting microscope we quickly reach the resolution limit.
The scale bar in the image below indicates that the tardigrade shown
has a modest body length of about 175 µm.
So we feel slightly envious when reading in the literature
that the species Batillipes mirus might reach "up to 720 µm"
in body length.
An adult Batillipes sp. tardigrade
with about 175 µm body length.
The big comparison scale line indicates the size of an adult Batillipes mirus
(700 µm body length) as quoted in literature.
Of course we would like to investigate the
anatomy of those maritime tardigrades more closely. It is quite clear that we
would prefer giant individuals for this task. As a consequence our plan
was to travel to the "Kieler Föhrde"in Germany from where
those giant Batillipes mirus individuals are reported in literature.
In the next issue we will tell you about our expedition to this legendary
place, quite close to the city of Kiel in Northern Germany.
Of course, we are working scientifically, with a global positioning system
and we make use of a special bus in order to come close to this Föhrde spot
(well, to be honest, it is a public bus line run by the city of Kiel,
coming close to our target area ...). See you.
© Text, images and video clips by
Martin Mach (firstname.lastname@example.org).
Water Bear web base is a licensed and revised version of
the German language monthly magazine
Style and grammar amendments by native speakers are warmly welcomed.