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Biologists at the University of Stuttgart identify three new tardigrade species

Tardigrades, also known as water bears, are true survivors. They have the remarkable ability to survive in extreme conditions - complete desiccation or freezing – without sustaining any damage at all! The organisms, which are about 0.2 to 1. 0 millimetres long, are mainly found in freshwater and in habitats such as moss and moist soils. Around 1,000 tardigrade species were previously known. Dr. Ralph Schill from the Institute of Biology at the University of Stuttgart and colleagues from the University of Würzburg have now discovered three new species thanks to a completely new method. Their findings were recently published in the journal “Organisms, Diversity & Evolution”.

Paramacriobiotus palaui, a newly discovered tardigrade species in the Pacific Ocean. © Schill/University of Stuttgart

The three "new" water bears originate from the tropical Islands of Palau in the Pacific Ocean, the cold areas of Alaska and from Kenya, which is why they were named Paramacriobiotus palaui, Paramacriobiotus fairbanksi and Paramacriobiotus kenianus. For quite some time, they have been regarded as cryptic species, although they were so similar to each other that it was impossible to differentiate them from one another. That is why the researchers chose to use the compensatory base change (CBC) method for investigating these tardigrades: Molecular biology and bioinformatic techniques are used to amplify a part of the ribosomal genes (rDNA), which is then sequenced, folded into its natural structure and examined for potential nucleotide exchanges. This method enables new species, which cannot be reliably differentiated from each other based on other sequences that are frequently used for such purposes, to be identified from their DNA with a probability of 93 per cent. These findings were combined with results gained with additional molecular biological, biochemical and physical markers, providing the Stuttgart researchers with the certainty that the three "new" water bears are actually distinct species.

Tardigrades, which are able to survive long dry and cold periods without any damage, are an ideal model system for studying survival mechanisms. "A better understanding of these processes will also lead to the development of new methods that will enable us to preserve cells and entire organisms without damage. This would be a great advantage for many areas in the fields of biomedicine and food," said Schill.

Tardigrades were first described by the pastor Johann August Ephraim Goeze as "little water bears". He wrote: "This animal is strange, because the build of its body is strange and extraordinary. And at first sight, it looks like a little bear. That is why I chose to call this animal 'little water bear'."

Further information:
Dr. Ralph Schill
Institute of Biology
University of Stuttgart
Tel. +49 (0)172/7304726
E-mail: ralph.schill[at]bio.uni-stuttgart.de

Literature:
Ralph O. Schill & Frank Förster & Thomas Dandekar & Matthias Wolf (2010). Using compensatory base change analysis of internal transcribed spacer 2 secondary structures to identify three new species in Paramacrobiotus (Tardigrada). Organisms, Diversity & Evolution. DOI 10.1007/s13127-010-0025-z

Website address: https://www.biooekonomie-bw.de/en/articles/pm/biologists-at-the-university-of-stuttgart-identify-three-new-tardigrade-species