What is a biosphere?
Biosphere All living organisms and their environments at the surface of the Earth. Included in the biosphere are all environments capable of sustaining life above, on, and beneath the Earth’s surface as well as in the oceans. Consequently, the biosphere overlaps virtually the entire hydrosphere and portions of the atmosphere and outer lithosphere. See also Atmosphere; Hydrosphere; Lithosphere. Neither the upper nor lower limits of the biosphere are sharp. Spores of microorganisms can be carried to considerable heights in the atmosphere, but these are resting stages that are not actively metabolizing. A variety of organisms inhabit the ocean depths, including the giant tubeworms and other creatures that were discovered living around hydrothermal vents. Evidence exists for the presence of bacteria in oil reservoirs at depths of about 6600 ft (2000 m) within the Earth. The bacteria are apparently metabolically active, utilizing the paraffinic hydrocarbons of the oils as an energy source.
