Chemosynthesis is the prime source of energy and many larger creatures have learnt to exploit the sulphur oxidising microbes that live here. What the first life forms were like is again open to discussion but they may have been even simpler than the bacteria and were also equipped to live in extreme conditions. Prokaryotes reproduce themselves by a method called binary fission where the parent cell divides into two identical daughter cells, this along with their speed of reproduction, size and their ability to change their metabolism has enabled them to be successful for so long. Bacteria can also produce spores that enable them to resist extreme conditions where most other larger organism would fail. This photograph was taken with a X40 phase contrast objective and shows bacteria in the act of spore formation.
Many spores can remain viable for centuries and even resist fire and freezing temperatures.
These spores are not reproductive cells. Photograph Steve Durr.1999. Banded iron deposits were laid down some 2 billion years ago and are between 50-600 metres in thickness. It is thought by scientists that these banded iron deposits could only have been laid down with the help of photosynthetic bacteria that would have thrived in the warm shallow volcanic vents. Eventually the amount of oxidation would cease and the free oxygen would begin to accumulate in the atmosphere.