Last week you learned about the possibility of life on other planets. As other planets were compared to Earth, you learned just how delicately balanced temperature needs to be. If the temperature is too hot, like Mercury, then life cannot survive. If it is too cold, like many of the outer planets, then life can survive either.

On Earth, not all kinds of life can survive anywhere on the planet. In fact, most life only can survive within a narrow range of temperatures. You've probably known this all along, which is why you don't put your goldfish outside in the winter.

Although individual organisms can't survive in a wide range of temperatures, organisms can be found at both extremely high and low temperatures. For example, tiny crustaceans in the arctic called "water bears" can only survive at temperatures below 4 degrees Celsius. In contrast, some single-celled organisms can live in temperatures as high as 110-115 degrees Celsius, possibly higher.


Source
http://www.astrobiology.com/adastra/extremophiles.html