|MadSci Network: General Biology|
Hi Ben, Actually, as I understand it, even the organisms around deep-sea vents are dependant on the sun as well, because the end of their chain of metabolism requires oxygen (an electron donor). Therefore, unless there was an oxygen reservoir in the deep ocean in "the early days," i.e. four billion years or so ago, the organisms around deep-sea vents are relative newcomers to the Earth (unless they evolved to exploit oxygen) and are "sun-suckers" as much as we are (a very old reservoir of oxygen is possible, but I'm not familiar with one). However, there are organisms in the crust of the Earth that MAY not be connected to the sun in any way. Organisms (bacteria) have been found in deep boreholes that metabolize sulfur found in the host rocks. Bacteria (and perhaps other organisms) evidently dwell in small cracks very deep in the crust (tens of thousands of feet), but I'm not familiar enough with their metabolism to know if the end of the chain is oxygen. With respect to "fundamental differences," I'm not sure at the level where bacteria operate that using oxygen or using some other electron donor as a step in the chain of metabolism could be considered "fundamentally different." In fact, metabolism as we know it requires a transfer of charge (electrons). In order to be fundamentally different, I would expect metabolism to operate in a "closed loop" of charge. Great talking with you, Ben. Keep the questions coming. ron
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