Study

Long-term anhydrobiotic survival in semi-terrestrial micrometazoans

Guidetti, Roberto; Jönsson, K. Ingemar

Journal of Zoology, 2002

Peer-reviewedcontrolled laboratory experimentlaboratory

What they did

Dried moss samples of documented age from herbarium collections were rehydrated under controlled conditions and examined for revived tardigrades, rotifers and nematodes, giving survival times anchored to a known date rather than to an estimate.

Studied in: Tardigrada, Rotifera, Nematoda
Sample size: dried moss samples of known age rehydrated under controlled conditions

What they found

Revival was obtained from samples up to around nine years old, with survival declining steeply with storage time. No revival occurred in substantially older material. Rotifers and nematodes showed comparable patterns.

What it means

The authors' reading, and ours. Where they differ, that difference is the point.

How the authors put it

Anhydrobiotic survival in these groups is measured in years rather than decades, and declines progressively rather than persisting indefinitely.

How NatureHQ reads it

Herbarium material is the right way to test this, because the date is documented rather than remembered. Around nine years, with survival falling steeply as storage lengthens — which is a long time for a millimetre-long animal to spend as dust, and is nothing like the century that circulates. The decline is the part worth carrying: the tun is not a pause button but a slow leak, and the question is how long before enough has gone.

Limitations

Herbarium storage conditions were not controlled for the purpose and vary between samples.
Absence of revival cannot fully distinguish death from failure to rehydrate under the conditions used.
Species identity in old moss samples is often uncertain.