Scientists Discover Leech Capable of Surviving Exposure to Extremely Low Temperatures

Posted on January 24, 2014

Ozobranchus jantseanus leech


Scientists discovered a leech that is capable of surviving at extremely low temperatures. The Ozobranchus jantseanus leech, found in East Asia, Japan and China, is a parasite of freshwater turtles. Researchers explain in an article in PLoS One how they exposed the leech to extreme temperatures, including storage in liquid nitrogen (-196 degrees Celsius or -384.8 degress Fahrenheit) for 24 hours. The leech also survived long-term storage at -90ºC for 32 months.

The researchers also found the leech has a high tolerance to freezing and thawing. The leech endured repeated freeze-thaw cycles in the temperature range 20 degrees Celsius to −100 degrees Celsius and then back to 20 degrees Celsius.

The researchers acknowledge it is unlikely the leech would encounter freeze-thaw cycles like this in nature. They say the amazing cold tolerance of the leech has "not arisen in response to some ecological need or that it is an environmental adaptation." Instead the scientists believe the cryotolerant ability "has arisen in response to some as yet unclarified adaptation."

The researchers also write, "We propose that, compared to other cryobiotic organisms, O. jantseanus exhibits the most robust cryotolerance ability reported to date. It is hoped that these findings will contribute to the development of new cryopreservation methods that do not require additives, and also to the resuscitation of organisms that have been frozen underground in permafrost areas, on Antarctica, and possibly on other planets."

Photo: Suzuki et al. /PLoS One