Hengherr, S., Brummer, F., Schill, R.O. 2008. Anhydrobiosis in tardigrades and its effects on longevity. Journal of Zoology 275:216-220

The water bear Milnesium tardigradum lives in habitats that often experience drought. To combat this, the M. tardigradum go into a period of dormancy called anhydrobiosis, where all metabolism in the organism stops. This dormancy is so effective that the animal can undergo complete desiccation and return to a normal state after rehydration.

But how does this affect the organism? Does it continue to age, or does the biological clock ignore the time spent in hibernation-like state? Or perhaps something in between, where it continues to age but at a slower rate?

To test this, the authors grew several groups of M. tardigradum on agar plates and subjected them to alternating periods of dehydration and feeding in a rehydrated state. The results showed no difference in longevity between the controls, which were kept in a constant state of hydration, and the organisms that underwent dehydration.

The findings illustrate that the M. tardigradum did not age while in anhydrobiosis. In other words, the time spent active was equal to the control however the total time the animal existed was increased significantly. Furthermore, the organisms returned to a normal state within thirty minutes of rehydration.

(194 words)

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(posted Dec. 22 2010)