You've likely seen the rubber ball in liquid nitrogen demonstration. After just a few seconds in the super-cold liquid, it freezes to the point where it will shatter upon impact.
Now imagine how crazy resilient anything alive would have to be to withstand such temperatures. Meet Ozobranchus jantseanus, an obscure leech that's a parasite of freshwater turtles.
Ozobranchus jantseanus, a parasitic leech, was found able to withstand extreme freezing temperatures. (Image source: Dai Suzuki et al. via PLOS One)
Scientists recently published a study detailing how this super leech can survive after being submerged in -196°C -- that's -320.8°F -- liquid nitrogen for 24 hours. Not to mention its ability to live for nearly three years in -90°C (-130°F) temperatures. After being frozen in such conditions, the leech was successfully reanimated after thawing.
To get an idea of why this is impressive -- and if you have never seen the aforementioned effect of liquid nitrogen on a racket ball -- watch this video demonstration:
The study published in the journal PLOS One this week describes the leeches "cryobiosis" -- it's ability to survive subzero temperatures -- as exhibiting a "wider range of temperatures than those reported previously for cryobiotic organisms." The authors go so far as to call it the "most robust cryotolerance ability reported to date."
The researchers also exposed the leech to the low temperatures quickly, not allowing what would generally be considered sufficient time for it to initiate some sort of cyroprotection for its cells. The compounds generally seen in animals that can be frozen and then reanimated were not observed in the leeches, which indicated to the researchers that they "may be capable of tolerating physiological water freezing in their tissues."
What's more, these leeches are not thought to have this as an innate ability. The study says that "it is unlikely that O. jantseanus would encounter similar freeze-thaw cycles in its natural environment […] so it is suggested that the cold tolerance observed in this species has not arisen in response to some ecological need or that it is an environmental adaptation. Rather, it is likely that this cryotolerant ability has arisen in response to some as yet unclarified adaptation."
Why should you care? According to the study authors, the ability to freeze and reanimate the leech in these conditions could make it useful in cryopreservation studies and "resuscitation of organisms that have been frozen underground in permafrost areas, on Antarctica, and possibly on other planets."