Long-term survival of microscopic animals under desiccation is not so long.

Abstract More frequent events of drought are predicted to happen in the future, but our ability to predict the effect on the biota may be limited by our partial understanding of extremophiles. Among the few animals that are able to survive in the absence of water for long periods of time are rotifers, tardigrades, and nematodes. Here, we take advantage of lichen collections stored dry at ambient temperature and humidity for years in museums, and through statistical modeling we demonstrate that the survival rates over time do not differ among animal groups but are strongly influenced by the type of substrate (the different lichen species). Our results suggest that desiccated organisms are prone to irreversible damage to biological structures, independently of the different biochemical processes involved in desiccation tolerance by different animals. The influence of the environment overcomes any taxon-specific response to survive extreme droughts. The predicted ability to survive for up to 10 years while desiccated enables these organisms to achieve potential global distributions, endurance against parasites, and even survival when exposed to outer space. Key Words: Anhydrobiosis-Dormancy-Nematoda-Rotifera-Tardigrada. Astrobiology 12, 863-869.