The Big Feast  or  The Feast of the Big Ones (II)

As mentioned already in the previous issue of our magazine we had found a population of Macrobiotus richtersi in tree moss cushions. One might argue that monocultures like this one could end up to be boring. But they have the big advantage that all properties and attitudes are cleanly associated with a single species.

Fig. 1: moss cushion, plucked off by birds, landed bottom-up, inhabited by Macrobiotus richtersi.

We had not shown too many photomicrographs of Macrobiotus richtersi in this journal previously, as Macrobiotus richtersi is seemingly confirming a common prejudice that all tardigrades are "worm-like" creatures.
But Homo sapiens does in fact comprise many worm-like, fat individuals as well, so we should be careful with verdicts like this one. Nevertheless we must admit that Macrobiotus richtersi has a lengthy body with little prominent features, showing no legs and no color.

Fig. 2: Macrobiotus richtersi. Its cylindrical body doesn't reveal much anatomic detail.

Fig. 3: Anterior body and head region of Macrobiotus richtersi. Characteristic macroplacoids (rows of three identically sized macroplacoids). We can follow the food on its way through the organism: entering by the mouth opening (a "kissing" type mouth) which is able to make permanent contact with potential food > then mouth tube > then the so-called oesophagus (a globular chewing stomach) > followed by a very faint, slim tube connecting to > the stomach-intestine region (grainy appearance).

Fig. 4: Tiny claws on the last pair of legs of Macrobiotus richtersi (Macrobiotus type symmetrical claws).

Fig. 5: Egg of Macrobiotus richtersi with typical conical protrusions. Total diameter ca. 125 µm.

Fig 6: egg of Macrobiotus richtersi as seen in strong backlight. Please note the network pattern between the egg protrusions.

After having seen the body of Macrobiotus richtersi we will go on with a discussion of its table manners in the upcoming March issue!

Literature
Ian M. Kinchin: The Biology of Tardigrades. p. 126-127. London 1994.
[Annotation: included is a comparison table listing the characteristics of the closely related species M. areolatus, M. hufelandi and M. richtersi plus a few images of their (very different) eggs]

© Text, images and video clips by  Martin Mach  (webmaster@baertierchen.de).
The 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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