【Extremophiles（极端微生物）areorganismsthathavebeendiscoveredonearththatsurviveinenvironmentsthatwereoncethoughtnottobeabletosustainlife．Theseextremeenvironmentsincludeintenseheat，highlyacidicenvironments，ex】

　　Extremophiles（极端微生物） are organisms that have been discovered on earth that survive in environments that were once thought not to be able to sustain life．These extreme environments include intense heat，highly acidic environments，extreme pressure and extreme cold．Different organisms have developed varying ways of adapting to these environments，but most scientists agree that it is unlikely that life on Earth originated under such extremes．

　　Adapting to Extreme Heat

　　In the 1960s，heat resistant bacteria were discovered in hot springs in Yellowstone National Park．This bacteria，thermus aquaticus thrives at temperatures of 70°C but can survive temperatures of 50°C to 80°C．A few years after these were discovered，other bacteria were found living under even more extreme conditions．Hydrothermal vents （热水流火山口） were discovered deep in the ocean and under such high pressure that the water boils at 340°C．It was a surprise to researchers to discover bacteria living and thriving in the vents at such extreme temperatures and pressures．Not only were there bacteria，but centimeters away where the water was cooler，was a complete ecosystem living off the bacteria．There were clams and tubeworms among other species．

　　Adapting to Extreme Cold

　　Other extremophiles have developed ways to cope with cold．Deep ocean water is as a fairly constant temperature of 2°C，but because of its salt content，in colder areas，ocean water can reach temperatures as low at-12°C without freezing．Extremophiles known as psychrophiles（低温微生物） are known to survive at these low temperatures．Different species have come up with different ways to survive these cold temperatures．Some have developed substances，such as glycerol（甘油） or antifreeze proteins which lower the freezing point of water by several degrees．

　　The main danger to organisms of freezing is the damage caused by ice crystals as water freezes and expands．Some species of frogs and turtles have p