Marine microbial diversity

Microbes were the only form of life for the first 2-3 billion years of planetary and biological evolution. Life most likely began in the oceans and marine microorganisms are the closest living descendants of the original forms of life. Early marine microorganisms also helped create the conditions under which subsequent life developed. More than two billion years ago, the generation of oxygen by photosynthetic marine microorganisms helped shape the chemical environment in which plants, animals, and all other life forms have evolved. Macroscopic life and planetary habitability completely depend upon the transformations mediated by complex microbial communities. These microscopic factories both aerobic and anaerobic are the essential catalysts for all of the chemical reactions within the biogeochemical cycles. Their unique metabolisms allow marine microbes to carry out many steps of the biogeochemical cycles that other organisms are unable to complete. The smooth functioning of these cycles is necessary for life to continue on earth.