Of course we were eager to compare our Echiniscus revival
results with those in the mentioned article. In short, the results were similar
but not exactly the same. Obviously the survival capacity of the Echiniscus
tardigrades is drastically reduced after four years (compared to revival experiments
with fresh outdoor samples). In our first experiment we found hundreds of
tardigrades which were immobile after rehydration and remained so. Even after
moving the tardigrades to fresh oxygen rich water not a single water-bear came
back to active life. But further identical experiments tought us that a very small
minority of the tardigrades was not dead - even after those four years.
Alltogether we found three Echiniscus tardigrades moving normally after 12 hours,
two Eutardigrades (Ramazzottius oberhaeuseri) feeding normally and two Macrobiotus
eggs which could be brought to hatching in the micro aquarium!
The percentage of living tardigrades was in fact very close to zero, far below one percent.
But keep in mind that a tardigrade population might fully recover with a single female survivor outside.
The revival process in those rare cases appeared to be retardiated. Whereas normal
tardigrade dry state "tuns" might come back as quickly as within five minutes
after rehydration, our "old" tardigrades remained many, many hours
in the asphyctic (anoxybiotic) state.
With the Echiniscus tardigrades, even after 12 hours the snouts appeared to
be still slightly retracted though the animals were moving and crawling
in a perfectly normal manner: