Microbial Organisms
by Sheri Lubin

Bacteria (in marsh pool)

Bacteria are an ancient and ever-present life-forms on our planet, often living in stressful places such as high-temperature, high-salt, or low-oxygen environments.  Many species grow in saline pools (giving the bright colors you can see from an airplane flying over the South San Francisco salt ponds).  Some are photosynthetic and some chemosynthetic, for example metabolizing sulfur giving rise to the "rotten egg" smells often encountered in a marsh.  These organisms can be found in standing water or ponds within the marsh and serve as valuable food for invertebrates and scavengers.

Microbial mat (at the edge of a pond)

 This mat is a living, diverse community of simple, single-celled organisms, mostly blue-green bacteria.  Bacteria are ancient life-forms, the earliest to evolve on earth, first appearing some 3.6 billion years ago!  The blue-green bacteria are the only lineage (family) that evolved photosynthesis as we understand the system today. Before they evolved there was no oxygen in our atmosphere!  They remain an extremely important component of the ecosystem today. Many are still free-living, such as these, but some became endo-symbionts about a billion years ago and enabled the evolution of all the major plant groups (green plants plus red algae and brown algae). 

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