Habitats and ecology

Microorganisms are found in almost every habitat present in nature. Even in hostile environments such as the poles, deserts, geysers, rocks, and the deep sea. Some types of microorganisms have adapted to the extreme conditions and sustained colonies; these organisms are known asextremophiles. Extremophiles have been isolated from rocks as much as 7 kilometres below the Earth's surface,^[50] and it has been suggested that the amount of living http://t1.gstatic.com/images?organisms below the Earth's surface may be comparable with the amount of life on or above the surface.^[28] Extremophiles have been known to survive for a prolonged time in a vacuum, and can be highly resistant to radiation, which may even allow them to survive in space.^[51] Many types of microorganisms have intimate symbioticrelationships with other larger organisms; some of which are mutually beneficial (mutualism), while others can be damaging to the host organism (parasitism). If microorganisms can cause disease in a host they are known as pathogens.