Ebay tardigrades (I)

Obiously, the world wide tardigrade species distribution pattern is difficult to determine. But there are very impressive national geographic distribution snapshots like the dissertation by Hieronim Dastych "The Tardigrada of Poland". You can imagine the tremendous work input by Hieronim Dastych and his co-workers when taking into account that his publication is based upon 5,261 samples with 81,532 (!) tardigrade individuals. Similar deep-digging work appears to have been performed in some other countries, e.g. in Italy, Austria, the Czech Republic, Sweden, France, Denmark, Greenland, Russia, Switzerland, The United States, Great Britain and Germany, with some of the publications dating back several or many decades.

The geographic distribution situation might appear to be even more complex when we think about how those national species distributions might change with time. Remember, nowadays we find numerous reports about so-called "alien" species - strange plants, frogs or shells that suddenly conquer a foreign region and suppress local populations. Probably it would turn out to be an endless task to follow the species distribution changes of tardigrade populations with time in all countries, all over the world.

And of course this type of scientific work is far beyond the scope of our very down-to-the-earth, popular magazine. But still we can try to understand the contributing mechanisms behind those changes by which also new tardigrade species might suddenly arrive in a region where they have not been met before.
It is well known that tardigrades are in fact travelling and it appears that they can be found among the first pioneer animal species which settle in new, possibly somewhat problematic regions. For example Fritz Heinis from Switzerland has shown already in the first half of the last century that tardigrades were among the limited number of new species that re-settled shortly after the terrible 19th century Krakatau vulcan catastrophy on an assumedly sterile ground.

The following quotation is based upon Heinis' results, too:

"A stone memorial was unveiled in 1904 and soon some moss cushions were found on it. After only two years two tardigrade species were discovered in those moss cushions. In 1927, i.e. after 23 years 5 tardigrade species were detected, which most probably have been transported to the stone by air."

[Translated from the German version which is contained in]
A. Kaestner (Ed.): Lehrbuch der speziellen Zoologie.
Vol. I, part 1, p. 594. Stuttgart 1969.

The air transport is favoured in the quotation above. But, as we will see, there are in fact many more possibilities for a worlwide tardigrade tourism.

I. Land transport on foot and as a passenger
The famous tardiologists Giuseppe Ramazzotti and Walter Maucci report tardigrade on-foot-travelling speeds to reach up to 17 cm per hour! Though this is an impressive performance for such a tiny animal there are more effective and more comfortable ways for one-way long distance tardigrade travelling:
all walking, running and jumping animals might transport tardigrades or tardigrade eggs in some way, e.g. with the tardigrade "tuns" or eggs clinging to animal hair or animal nutrition.

II. Water transport
We have already mentioned ocean travelling tardigrades settling on Sargassum algae in an  early issue  of our magazine. Moreover tardigrades by sure will travel on our rivers making use of all kind of wooden material carried along by the water. Last but not least tardigrades can be found in every city wastewater system, alive.

III. Air transport
Though wind transport has failed in some experimental studies there can be no doubt that a heavy storm will be able to transport ground particles, leafs etc. with inhabiting tardigrades over a long distance. And you will not need much phantasy in order to imagine that tardigrades might be transported e.g. by birds which tend to collect moss cushions for nest construction.

And there are many modern transport systems introduced by man. Just think about long-range fruit transports, Bonsai trade or moss christmas decoration imported from China. As a further example we have picked out one of the most recent tardigrade travelling mechanisms: Ebay internet auctions!

In order to prove this we have ordered a "Decoration moss assortment from the Canary Islands" via Ebay. It was delivered to Germany by air-mail for a few Euros. Probably you will agree that the Spanish stamp on our Ebay moss package might be considered as a sufficient evidence that it came actually from the Canary Islands:

Stamp on our Ebay package from the Canary Islands.

We liked the content of it even without the use of a microscope ...

Mosses and lichens contained in the Ebay package. Perfectly dry and well preserved.

... in particular when looking closer:

Mosses and lichens contained in the Ebay package. Detail view.

Bonus material included with a cheap microscope: "Ceylon moss". Sad enough, there was virtually no life to be found in it after water immersion, not even the tiniest rotifer  :-(

Heterotardigrade from the Canary Islands. Body length ca. 250 µm.