Life below freezing
    It is hard for life to survive and reproduce below the freezing point of water as ice crystals form, fatally rupturing cell walls. In 1992 scientists discovered a single-celled organism, "Methanococcoides burtonii", which lives and grows at -2.5°C. Flexible cell walls and an ability to produce their own ‘antifreeze’ enable some bacteria to survive a chilling -20°C.

    Life in acid
    Acids can eat through human flesh in second, damaging cells and ultimately killing them. Yet there are some life forms, like the red algae "Cyanidium caldarium", that have adapted to survive, and even thrive, in the most acidic of conditions, such as the hot volcano pools found in Yellowstone National Park.

    Life above boiling
    In 2003, scientists studying a volcanic vent 2 km under the sea and discovered a single-celled organism that can cope with temperatures of 121°C. They named it "Geogemma barossii". Since then, these creatures have been found living happily under the enormous pressures found at the bottom of many of the world’s deepest oceans.

    Life without air
    In the vacuum of space there is practically no water or oxygen, and the intense cold and radiation are extremely harmful to most life. But experiments have shows that at least one strain of bacteria can survive for over six months in space, by hibernating. Bacteria could be hibernating on distant worlds with little water or oxygen, just waiting for the right conditions to blossom into life.

    Life in ice
    This microorganism was discovered under 4 km of ice, just above Lake Vostok, Russia. Lake Vostok is a massive body of liquid water buried under the ice for 400,000 years. It may contain some very unusual life, and having been isolated from the rest of the planet for so long.

    Life under high radiation bombardment
    The bacteria "Deinococcus radiodurans" can survive doses of radiation 3,000 times greater than that need to kill a human being. Radiation destroys DNA but this creature has a spare copies of the most vital bits, as well as speedy DNA repair mechanisms.

    Life in salt
    Salt in large quantities can pose a danger to life because it sucks the water from cells. However, the organisms such as "Haloferax volcanii" have adapted to live in extremely salty conditions, and can even survive for thousands of years in dried-out salt lakes.

    Rock-eating bacteria
    Buried deep underground, well away from sunlight or oxygen, there exists one of the strangest forms of life on this planet. This strain of bacteria lives on hydrogen and carbon dioxide given off from the surrounding rock.