On the cover of one of the tardigrade monographs by Ernst Marcus
we find the Latin inscription: Sine systemate chaos . The user
of the book by this is asked to accept that any study of zoology doesn't
make much sense without an inherent intellectual framework.
As the Water Bear web base is aimed towards microscope amateurs we might
of course simply point out our amateur status and pass on all the difficult
problems of taxonomy to the professional scientists.
It should be a warning for us that the key for determining water bear species
in Hieronim Dastych's book about the Tardigrada of Poland comprises ten full
The water bear species in particular have the reputation of being difficult
to discern. Heinz Streble und Dieter Krauter, famous authors of the most
popular textbook on pond-life in Germany (see literature) discuss this
problem - as everything else in their book - in a straightforward, short and honest
The exact species determination on the basis of claw type, egg form
and sclerified inclusions (macroplacoids) within the buccal aparatus
On the other hand zoological systematics provide us with a unique tool
for precise communication with other people.
Each animal within the Kingdom of Animals has its own unique name
as defined by the rules of Linné.
Keeping in mind the complications of tardigrade species determination
we will have a very simplified look at species definition here.
First of all it is important to understand the basic nomenclature of
species. Let's look at an example:
The water bear species name
Macrobiotus areolatus MURRAY, 1907 bears
systematic information as follows. The first term "Macrobiotus" indicates
the order (genus) name which is the same for a group of similar (related)
species. The genus name is unique for all animals and therefore is a very sharp
The second term "areolatus" indicates the exact species within the genus group,
i.e. it is lower in systematic hierarchy and at the same time even more precise.
As a rule the species category is defined by the ability to produce
children wheras different species will not be able to mate successfully.
"MURRAY" is the name of the person who discovered (described) the animal for
the first time with sufficient professional quality. "1907" is the year
of the publication.
It is not absolutely necessary to add the name of the discoverer and the
year of the publication, as a rule these data are added just for additional
When we look up the genus name "Macrobiotus" within the reference literature,
we will also find the higher levels of the zoological hierarchy.
In our example the genus Macrobiotus is a part of the higher grouping Eutardigrada.
The Eutardigrada again are a part of the water bear phylum .
The red cells within the table below show the line of determination beginning with
the phylum, passing on to the order Eutardigrada, the genus Macrobiotus
and, as an example, the exact species Macrobiotus areolatus.