The Small World of Freshwater Gastrotrichs
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The Small World of Freshwater Gastrotriches

Gastrotrichs - or hairybacks - are microscopic multicellular animals living hidden in almost any water body, unknown to most people. Yet they are the most abundant multicellular organisms in many habitats and, together with rotifers, form the basis of the multicellular fauna in freshwater. Nevertheless, comparatively very little is known about their life cycle and their biology, and many an enthusiast of microscopic study has had no or only a very fleeting encounter with these beautiful and interesting animals, even after years of study of the “life in the pond”.

Species diagnosis

Therefore, I would like to dedicate a web-site to these shy stars of the pond, where freshwater gastrotrichs will be described in detail. Marine gastrotrichs are not treated on these pages. Therefore - if not explicitly stated otherwise - the term “gastrotrichs” is used exclusively for the freshwater fauna.

This web site is intended to assist both the dedicated amateur and the professional observer in the microscopic observation and identification of freshwater gastrotrichs. Therefore I try to collect short descriptions from the literature for as many known freshwater species as possible and present them in a systematic order. If possible, this information is supplemented by high quality photographs (where appropriate, photographically documented species are marked with a “📷”) and identification hints for light microscopic species diagnosis are given, which have proven successful in my observations.

  • Of the 397 freshwater species described, this web site includes for 379 Species individual pages.
  • Of these species, no literature references could be found for 325 species
  • For the remaining 41 species a profile from the literature was taken over in each case
  • Observation photos were added to these profiles for 0 species observation photos were added

The second part deals with the biology of freshwater gastrotrichs. In addition to the anatomy of the hairybacks, their peculiar life cycle is also discussed here.

By using microaquariums, it was possible to observe hairybacks continuously over an extended period of time (several weeks). This provided unique information about the behavior and development of gastrotrichs.

  • In total this web site contains 0 individual pages on the topic “Biology”
Finally, in the section “Technique” hints shall be given on the necessary or by me used apparative equipment as well as on the preparation techniques used for the observation of hairybacks. Here you will find instructions that allow, for example, high-resolution observations or to perform long-term studies of the development and behavior of gastrotrichs.
  • In total this web site contains 8 individual pages on the topic “Technique”

As with all web sites, this one is never finished and competes with my other interests for my scarce time. Therefore - despite all care and dedication - there will always be gaps and mistakes in the content. The gaps I hope to close in the course of time - with the errors I depend on your assistance. Please don’t hesitate to point out problems or inaccuracies - I’m always grateful for constructive feedback!

This web-site does not consider itself a scientific publication. Therefore, in favor of clarity and simplicity, I refrain from the last “scientific” caution on some topics. For example, in order to achieve the necessary scientific certainty in species identification, it will often be necessary to verify the species diagnosis using the given literature. This web site is only intended to facilitate a first introduction to the great subject of “gastrotrichs”.