Lichens are pretty amazing things. Lichens are composite organisms, consisting of a fungus and an
alga or cyanobacteria (blue-green algae), or all three together. There are many kinds
of lichen. Basically they are fungi and algae in symbiotic union. Fungi lack chlorophyll,
which algae have. Photosynthetic algae produce the nutrients that Fungi need, while
the fungi provide a strong highly resilient structure to exist in, and the water
necessary for photosynthesis. Fungi (mold for instance) can spread widely. And algae
can be single celled or very large. Giant kelp is an alga.
Algae are mainly aquatic. But combined with a fungus they become the plants of the
Lichene group, which are found almost everywhere on the planet. Lichens migrate quickly
onto newly deglaciated land. Lichenometry is a method of measuring lichens, and thus
glacial recession and other geomorphic events such as landslides. Lichens are also
good indicators of the rates of plant colonization on proglacial and other empty
landscapes.
Although greatly affected by environmental conditions, lichens thrive where other
organisms cannot. They colonize everything from bare rock, to metal - even plastic.
(Mother Earth will reclaim and remake it all eventually.) Lichens exist in almost every clean
environment, from freezing arctic regions to dry hot deserts. If it is too cold and/or there
is not enough moisture in the air, they will simply go dormant until conditions improve.
Lichen on Wood - Click for larger window
There are lichens and moss on this bark.
Lichens help with soil production by producing chemicals that promote the
degradation of rock. Lichens may get some nourishment from the minerals in the rocks
they grow on, as well as from trees or other substrate. But lichens are not parasites.
Photosynthesis from the algae provides
most of the necessary sustenance, and that mainly comes from the air.
Generally lichens are beneficial to the plants and animal life around them.
Cyanobacteria turn atmospheric nitrogen into compounds that contribute to the fertility
of the soil. Motile - free-living - cyanobacteria fix nitrogen in much the same way as
the roots of legumes do. Fixing, or combining, nitrogen means converting nitrogen into
new compounds such as proteins and nucleic acids. Free-living bacteria, like
the blue green algae in lichens, have the ability to independently move about the system.
They combine simple inorganic nitrogen from the soil or atmosphere with other elements to
produce these complex compounds, which can then be consumed by other plants and animals.
Changing the lichen images above into grayscale to see if they look a bit more Martian
Not quite like the Mars grayscale images. But one can get an idea of things.
Do these look like the "trees" on Mars?
sort of - not quite
But there are many kinds of lichen.
Lichen from Alaska
These are very small. Imagine them very big.
Dendritic Lichen (I think) from Alaska
Very bushy
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Top View
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Enhanced
Insert - compared to MOC image, m0804874
Does this work?
How about this one?
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These images from
m1001442, segment A.
Browse Page for
MOC m1001441
Notice the dendritic patterns in the second image.
Could there be such organisms thriving at the south pole of Mars - and elsewhere
on the planet?
Someone asked this question about the possibility of giant life forms like
worms.
What do they eat?
On Earth worms eat organic matter, and lichens eat nitrogen.
Inorganic nitrogen consumed by lichen produces proteins - amino acids.
And photosynthesis produces carbohydrates from carbon dioxide.
The oldest known fossil is cyanobacteria.
Lichens may be among the oldest life forms on Earth.
This makes me wonder if the big question is not about life existing on Mars in the past.
It is easy to think of an extinction event taking away most of the life on a planet.
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