Scientists have reported that they were able to “revive” a tardigrade after it had remained frozen for more than 30 years. The research is described in the journal Cryobiology.
Tardigrades, also called “water bears,” are known as extremophiles, which means they can inhabit a vast range of harsh environments. They are tiny microscopic invertebrates, typically less than a millimeter in length, with four pairs of legs and claws. But despite their widespread habitability, much is still unknown about them.
In this research, the scientists described how two frozen tardigrades, Acutuncus antarcticus, and an egg were found on a moss sample from Showa Station in Antarctica in November 1983. The tardigrades were then stored at a laboratory in Japan at a temperature of -20°C (-4°F), reported Gizmodo.
While in their frozen state their metabolic activities shut down, placing them in a state called cryptobiosis, showing no visible signs of life. So in March 2014, the scientists thawed one out to see if it would “return to life.” Amazingly, after 13 days, its bodily functions were almost back to normal, and was able to eat algal food. Later, it even laid 19 eggs – 14 of which hatched.
In their paper, the researchers note that this is the “longest recorded cryptobiotic duration of survival for tardigrades as animals or eggs.” However, they note limitations, such as it being unknown how much moisture the moss initially contained. That's important, because dehydration would also have an impact on the organism.
As noted by Gizmodo, this is also not the longest record for a frozen organism to be revived. “That distinction belongs to a plant-parasitic nematode worm, Tylenchus polyhypnus, that survived after nearly 39 years in a frozen state,” they explained.
Nonetheless, it’s still an impressive feat. And it just adds to the multitude of evidence as to how resilient tardigrades are in any environment they inhabit.