Dujardin published three drawings of his Microlyda and thus cemented
his reputation as the first discoverer of a sea water tardigrade. Later on
scientists commented in deep respect: "Dujardin was the first man on earth
to know a marine tardigrade". Microlyda has never reappeared since then.
14 years later, in 1865 Max Schultze from Ostende, Germany, announced the
discovery of a further marine species which he called Echiniscoides.
Echiniscoides lives on green algae at the seashore. As a consequence this species
was among the first losers in the hide-an-seek between tardigrade and man.
One might assume that the worldwide introduction of apochromatic microscope optics
(since 1872) might have helped to find those many more marine tardigrade species as known
today. Strange enough the highly-motivated scientists didn't find
anything else, even with the new costly apo optics. In the end of the 19th
century it was Lucien Cuénot who safeguarded the honour of the scientific
community by his discovery of the tardigrade Tetrakentron synaptae
on the whiskers of the sea cucumber.
Also Prof. Ferdinand Richters, discoverer of many terrestrian tardigrade
species, encountered difficulties with those marine species. He explains the situation as
follows: "in August 1908 I was invited to take part in an excursion by
the zoological institute of the Kiel University organized by Prof. Apstein und Dr. Reibisch
on a little steamship called "Frieda". We fished at the "Stoller Grund"
landmark (close to buoy 2), at a depth of about 20 m and recovered some
stones covered by Fucus vesiculosus und serratus.
... When screening the respective sediment in October I found three individuums
of a new, really bizarre tardigrade which I would like to introduce to the scientific
community under the name of Batillipes mirus .
End of November Prof. Apstein re-checked the same location and took additional
samples. After three weeks of searching I was able to find just two more
individuums in those new samples. Other samples from the Small Belt, from Fakkebjerg
and Oderbank didn't contain a single further tardigrade." [translated
Nota bene: after a three weeks' search ... two tardigrades!
It took a long time, decades in fact, to find further marine species. Today many
more species are known and even more are suspected to wait for future discovery.
The resume for us is fairly simple: searching and finding marine tardigrades
cannot be easy. Also a quick web image research reveals that the number of marine
tardigrade photomicrographs in the internet is rather modest.
Though reknowned as to be among the most abundant articulate animals it is
difficult to get hold of the marine and maritime tardigrades. One reason
is that they are the dwarfs among the tardigrades, slim, transparent,
with a body length of 0.1 - 0.2 mm. As we have learnt that the ordinary
terrestrian tardigrades are already marvels of ultra-miniaturization it
is really surprising to find further tardigrades which are even smaller.
Starting from the next issue we will inform you about our own experiences
in marine tardigrade search. But, please be warned: you will have to invest
much more time and energy in order to study those evasive beings
and you might even be unable to re-find them on you slide. Sometimes
you will be happy to get a view of their backside before they will vanish behind
the next sand grain - but this is of course still better than to find nothing at all: