Archimedes Plutonium wrote:

I realize the primeval Earth when life began had a far different
environment especially in gases and temperature.

So what I am looking for if we say the blue green algae were the first
plants is some organism that lives off of the blue green algae and
interacts in some manner with blue green algae whether it is alive or
after it dies.

This still verging on the ridiculous.

As far can be told, the first bacteria did not use light in their
reactions, and were effectively entirely "rockeaters". Then at some
point a strain evolved that could combine elemental sulphur and hydrogen
from the atmosphere to produce energy, albeit inefficiently.

The big breakthrough came when a variant on this strain started to use
light to push the reaction in the other direction: it took the then
fairly abundant hydrogen sulphide and produced elemental sulphur and
hydrogen.

Neither of these bacterial types altered the atmosphere much, however.
That came with a small mutation in the genes that coded for the H2S
splitting enzyme.

The mutant form split water instead of hydrogen sulphide. This produces
oxygen, which was then rather troublesome for the bacteria since
everything alive then was poisoned by oxygen. Gradually a more tolerant
strain evolved, and true plant-like behaviour took over. The oxygen
levels at first stayed low through weathering of rocks and iron
minerals, then eventually took off exponentially.

The relevent point here is, where do you draw the line? What IS a plant?
The hydrogen sulphide reducers are acting like plants, but the compounds
they're reducing are rock-derived.

The relationship of plants to animals today is that animals depend on
plants for food but plants depend on animals for fertilizer.

So I need a relationship between blue green algae and some other
organism.

How's about a relation between photosynthetic predatory protozoa and
other photosynthetic predatory protozoa?

Down at the microscopic level, with bacteria and protozoa, the
plant/animal dividing line is extremely blurred. An organism might one
day be wholly photosynthetic; it might the next be 50/50
photosynthetic/predatory; it might then become a predator for a brief while.

Why bother with the line?



--
Dr Dan Holdsworth
Remedy ARS Administrator, Manchester Computing

0161 275 0606