Symbiosis

Xanthoria parietina growing slowly on a weathered doorstep in a car park. One of the extraordinary and ancient wonders we step over every day as we do what humans do far too well - live banal and bored lives in a Universe of unimaginable beauty and complexity. Lichens are of course two organisms living in extraordinary intimacy to produce a life form unlike either. A fungus and an algae. On its own the algae might manage to survive as a powdery smear on a tree trunk but the fungus in this case would just be a mass of mixed up, unstructured hyphae if coaxed into life on a Petri dish. Together they produce this extraordinary and beautiful form. The fungus provides the bulk of the structure, protecting the algae within it and providing it with nutrients captured from the environment. In return the algae captures energy from sunlight through photosynthesis and feeds both of them. The relationship of the cells is so intimate that the algae are actually pierced by fine hair like structures from the fungal cells - carrying nutrients in and transporting photosynthesis products out. Two forms of life evolving on their own and now evolving together in a dance of coordination and adaptation. Recent studies have shown that lichens such as this can survive, and thrive, on Mars. In an 18 month experiment on the International Space Station lichens survived intact and viable through unfiltered UV, cosmic radiation, vacuum and extreme temperatures - a quick drink of water and off they went, happily growing at their slow, slow pace.