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This is not an organism - it's two. Among all the lifeforms on earth, there are few that rely so heavily on a relationship with another.
Classifying them depends on an understanding of just how these two organisms live as though they were one.
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Along the weathered coastlines of North America's Gulf of Mexico, dunes give way to scrubland.
This unique habitat, so close in proximity to the ocean, forces organisms to survive in highly saline conditions.
The resulting plant life is adapted to the hot and salty landscape.
There are few species of tall trees; most plants grow to smaller heights, and with a lack of canopy to provide shade.
most everything is exposed to the sun.
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It's a difficult environment for algae to survive.
Algae, a kind of bacteria, die when they become dried out.
But algae, like plants, require some sunlight in order to carry out photosynthesis and create food for themselves.
In order to obtain sunlight while retaining adequate moisture, some algae have formed a relationship unlike most others on the planet.
The algae's counterpart in this relationship is fungi.
While algae are able to make their own food through photosynthesis, fungi cannot.
But when living in tandem, fungi and algae can provide what the other lacks. This tandem is known as a lichen, a type of symbiote.
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In the scrubland along the Gulf, lichens make their home on exposed ground.
While algae alone might dry out under such conditions, the fungi with which they're partnered provide protection to keep the algae moist.
The algae, in turn, is able to feed both itself and the fungi through its photosynthesis.
Without roots, lichens absorb from the ground the nutrients that they would otherwise have to pull from the ground.
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This cooperative relationship makes lichens formidable in almost any habitat.
With a protective structure and no need for roots, lichens can live on rocks, trees, and other natural features on which other organisms
would be unable to survive.
As such, lichens of similar forms as those present along the Gulf of Mexico are present as far north as Alaska.
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These symbiotes, surviving within a biologically novel relationship, are able to make a home for themselves in landscapes that
would otherwise pose significant challenges to the survival of each organism individually.
By doing so, lichens carve for themselves a niche in the most inhospitable of environments and among the most
unique relationships in the natural world.
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