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Krapanj (II)

In the previous issue we had praised the tiny Croatian island called Krapanj. No cars, no tourists' hotel blocks, little noise - and many, many tardigrades!

[ View from our pension room at Krapanj towards the sea ]

View from our pension room at Krapanj towards the sea

Humble landmen like us tend to enjoy this kind of view, in particular the great distance which is open to the viewer. And it is fascinating to imagine those billions of tardigrades living out there in the sea. Besides the distant, visual borderline between sea and sky has a kind of bizarre, unreal appeal when studied by means of a telescope:

[ The sea horizon as seen by means of a telescope ]

A telescope view of the distant sea horizon, as photographed through a telescope. The "tail" of the island on the right hand side appears to be hovering above the water, it looks like some kind of symmetric wedge. And the small single-mast sail in the center of the image makes us understand the legend of the "Flying Dutchman": It is levitating above the water. Only by means of the island "wedge" we are able to judge where the real borderline between sea and sky is actually situated.

At our home town in Munich there is no sea horizion and no Flying Dutchman. We have to resort to the micro aquarium which will serve as a true marine souvenir, still bearing a considerable portion of marine life within its walls. Meanwhile the Ferrero company has come up with a new sweets container for their "Mon chéri" pralinés. This one is even better suited for our needs than the "Rocharium" (with the so-called Ferrero "Rocher" sweets) which we had described previously.

[ <Mon Chérie> micro aquarium ]

A new micro aquarium as produced by the Ferrero company. This elegant "Mon Chéri" container is measuring 15.3 cm x 7.85 cm x 4.5 cm. It is still able to mimic some kind of micro Mediterranean Sea, even better than the previous Rocharium with its higher side walls. Transparent, highly useful and simply marvelous!

Due to the lower side walls this micro aquarium can even be directly investigated under our cheap stereo microscope:

[ <Mon Cherie> micro aquarium under the low-mag stereo microscope ]

The "Mon Chérie" micro aquarium under the low-mag stereo microscope

Of course this mediterranean miniaturization has its limits. In particular slightly bigger organisms like small hermit crabs or algae will constitute a risk for the biological equilibrium in the micro aquarium. A beautiful sea snail as the one shown below can serve as an example for this problem: At the moment its body length is just a few millimeters but in case it should continue to grow further beyond this size it might completely wipe out our aquarium life scenario. Besides it took us several months to become aware of this animal in our small aquarium, a fact which is once more indicating the marvelous adventures and suprises to be expected when sreening through such a stunning micro universe.

[ Sea snail in the micro aquarium ]

Small sea snail, photographed directly within der micro aquarium. Body length ca. 3 mm.

One big advantage of the sea water micro aquarium is that you will be able to enjoy it at home, in a much more relaxed atmosphere than e.g. inside a sun-lit holiday hotel room. As a consequence enhanced studies are easier to accomplish. With this advantage in mind we planned to come to a better understanding of the anatomy ot those marine tardigrades. Even then it was very difficult in the beginning just to tell the front ends from the hind ends. (cf. this Water Bear web base issue).

[ Florarctus under the low-mag stereo microscope ]

View of a Florarctus sp. tardigrade under the low-mag stereo microscope. Please note the bilateral-symmetric stomach-intestine system. Legs and claws are small and poor in contrast, therefore cannot be easily seen at this low resolution. The small black structures, at position 7 o'clock on the above photograph are marking the front end of the tardigrade whereas the "hole" in the brown intestine structure (at position 1 o'clock) is revealing the position of an egg. Well, we are fully aware that this is a very modest anatomy discussion yet, just a beginning. Image width ca. 1 mm.

And this is what the face of those tardigrades looks like::

[ Florarctus frontal ]

Front view of a Florarctus sp. tardigrade. One tends to assume that the dark spots should be interpreted as eyes. Please note the "wings" which are characteristic for the genus Florarctus. Image width ca. 0.1 mm.

The same dark structures as seen under the bigger compound microscope:

[  ]

Floractus as seen from above. Head on the lower left side with parts of the sensor antennae faintly visible. Nodal structures with unknown function on both sides of the mouth tube. The thin cuticular "wings" (reminding of an open rain cape) show only little contrast, cannot be seen under the brightfield illumination conditions which were used here. Image width ca. 0.15 mm.

To cut the story short: Florarctus is revealing a lot of transparency and only little detail when studied under the low-mag dissecting microscope (stereo microscope). And we are not sure whether the nodal structures as described above might be a part of the stomach-intestine system or not. Please send us a note in case you should have some information about this topic.

© 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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