Draft treatment: lichen
New York from on high. We descend towards a crowded sidewalk. Hundreds of people scurry up and down, getting on with their busy lives. We sink through them, down to their tramping feet and see, like a piece of squashed gum.... Lichen! Pedestrian feet fall above it, below it and to each side.
Now the Lichen occupies the whole screen. A female voice begins to narrate.
‘To the naked eye, Lichen looks like an individual plant. But under a microscope, you can see something remarkable.’
We zoom in 400x. We’re in the Lichen’s world now. Everything the narrator describes is documented using footage of Lichen taken through a light microscope, it’s all perfectly obvious to see.
The cells that make up a lichen are not genetically related: Some are Fungal, others are Algal. Lichen is a real, living, naturally occurring chimera. A collaboration between a Fungus and an Alga. They work together: The main body of the Lichen, the thallus, those leafy parts you can see, is the Fungus. The Fungus grows in long filaments that anchor the Lichen to a surface. Its tough cells provide protection from hungry grazers. The color of the Lichen comes from Algal cells buried among the fungal cells. The Algal cells are softer, but they are powerful. They transform sunlight into sugars and energy. The Algal cells share this energy with the Fungus. The two organisms live together, sharing resources to improve each other’s lives. The Fungus provides a safe home. The Algae lives within, and pays rent in the form of energy. On their own, each is an individual species, one Fungus, one Alga. Together, they are a new, chimeric lifeform: The Lichen. It’s a cozy arrangement. Until they decide to reproduce.
Both the Fungus and the Alga reproduce separately. Then each organism must find a mate to pair with, so they both gain the benefits of working together as a Lichen.
The Fungus produces spores to disperse itself.
Many new Fungal spores hold onto an Algal cell during dispersal. They’re starting a life as partners.
The Lonesome Fungus
This one’s not so lucky. It’s lost hold of its Algal friend, and must start again, as a lone Fungus in need of its perfect partner. To become a Lichen, it must find and fuse with an Alga. It needs to find an Alga that is alone, one that wants to enter into a partnership with a Fungus.
This Fungus is embarking on treacherous journey. In our sense of scale, it may only need to move a few millimeters, but when you’re only a small fraction of a millimeter tall, success seems a long way away.
Life threatening event #1: Avoiding the hungry ciliate.
First, it has to avoid being eaten. Predatory ciliates are everywhere. These are hungry microbes. They feeds on whatever they can hoover up with their powerful cilia. Many Fungal spores end their short lives as supper.
But not our one: it’s had a lucky escape.
Life threatening event #2: Rejection.
Being eaten is not the only danger for a Fungus in search of an Algal mate. The next obstacle is rejection. You can invest a lot in one Alga only to find that it’s just not going to work.
Life threatening event #3: Swimming through corpses of other Fungi.
The Fungus moves on. There may be plenty more Algae in the sea but if you don’t find an appropriate mate, the risk is that you run out of energy and die alone – a fate this Fungus encounters as it passes through the corpses of its un-partnered fellow kind.
Life-threatening event #4: Inability to steer.
Finally, a potential mate. Unfortunately, our Fungus has no motility – it can’t steer! What could have been its perfect partner just floated by out of reach.
But for the persistent, and the very lucky, there’s always another chance, and after a miraculous journey, our hero encounters its perfect mate. Life for these two will go on, and, as so often in life, they’ll find its better together.
We zoom out of the microbial world back to the Lichen on the street, and further back, till we see a pair of tan leather shoes, stopped beside it. Their owner crouches down. Then we can see who they belong to: Pondlife creator Dr. Sally Warring. She speaks to camera.
“That’s a process that has repeated millions and millions of times, often ending in failure, in this one tiny patch of Lichen. Perhaps next time you see one, you won’t be so quick to walk by.”
We rise above the street and see a whole crowd of people gathered around Dr. Warring who’s talking with them, then higher still as the street becomes one of the thousands that make up New York.