It all started with a frozen turtle.
A team of researchers from Tokyo University of Marine Science and Technology and the National Institute of Agrobiological Sciences pulled a frozen turtle out of deep storage, where it had been sitting at 112 degrees below zero for six months. The turtle, obviously, was dead, and the researchers wanted to study its anatomy. Instead they noticed that several one-centimeter-long leeches that had been stuck to the turtle for that entire time started wiggling around after they warmed up.
I don't know about you, but at this point I would have run from the room screaming "zombie leaches," but I guess the scientists had cooler heads.
The researchers realized they had something unusual in their hands. The leeches, from a species called Ozobranchus jantseanus, could withstand and survive temperatures much, much lower than just about any other animal on earth. The researchers set out to test the limits of that ability.
Ozobranchus jantseanus lives on several species of freshwater turtles in Asia, so the researchers gathered a bunch of the leeches as well as samples from several other species. They then started a series of deep-freeze, long-term experiments to figure out just how much cold this leech could take.
The leeches weathered the experiments like little troupers. While the other species turned into tiny popsicles, the Ozobranchus jantseanus leeches did just fine. They survived temperatures of -130°F for an unbelievable thirty months, which makes me feel like a wimp for complaining about this year's winter up here in Maine. Even more astounding, the leeches survived a whole 24 hours after being immersed in liquid nitrogen — that's -321°, folks — something that would kill just about any other creature.
And the leeches didn't just survive a single freeze. They survived multiple freezes and repeated freeze-thaw cycles, with temperatures ranging from -148° to 68° and back again. And again. And again.
In one way the ability to survive these cold temperatures was not unexpected. Similar water-based leeches can survive low temperatures of their natural habitats. But this particular leech not only did well at significantly lower temperatures it did so without the presence of water.
So what's the significance of all of this? Well, other than the fact that's it's pretty amazing – and pretty freaky – the researchers say this leech's unique abilities could provide clues into cryopreservation, where living creatures or tissues are purposely frozen for the purposes of warming them up (and bringing them back to life) at a later date. Plus they just wanted to freeze a bunch of leeches.
The research into the Ozobranchus jantseanus leeches was published January 22 in the journal PLoS One.
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