Cryptobiosis refers to when organisms display extremely low, barely detectable levels of metabolic activity. Several strategies of cryptobiosis are known, with long-term survival under cryobiotic (freezing) conditions not having been widely reported. Although many researchers have studied the long-term survival of various species of micrometazoans, many of the previous studies focused solely on the survival of the stored organisms, not their post-thaw reproduction abilities. In this study, researchers focus on investigating tardigrades obtained from an Antartic moss sample that was stored for 30 years at -20C. Even though one of the two tardigrades died days after thawing, the other acquired tardigrade was able to survive and reproduce after 30 years of cryptobiosis. Additionally, one egg was retrieved from the moss sample, that hatched and subsequently reproduced as well. This represents the longest recorded cryotobiotic duration of survival for tardigrades as animals or eggs. Detailed understanding of the mechanism of their mechanism of survival can allow the replication of this method on other species.

Recovery and reproduction of an Antarctic tardigrade retrieved from a moss sample frozen for over 30 years. Megumu Tsujimoto, M., Imura, S. , Kanda, H. Cryobiology 2016. 72: 78-81