Lichens are organisms that consists of fungus and algae. Together they are able to live in places where neither of them could live alone. The hyphae of the fungus protects the algae and supplies it with water and minerals. The algae produce its own food through photosynthesis — it eats sunshine to make carbohydrates — which it then shares with its fungus partner.
We know of more than 20,000 different fungi which live — in symbiosis with alga — as lichens, and different types of lichen cover about seven percent of the earth’s total surface.
It was Swiss botanist Simon Schwendener who, in 1867, first declared that lichens are a composite of fungus and algae. 10 years later, German mycologist Albert Bernhard Frank termed the word symbiotism to describe this mutualistic relationship, but it was his fellow countryman and fellow mycologist Heinrich Anton de Bary who further tweaked the word and came up with symbiosis, which is the one that stuck in our lingos.
Almost simultaneously Belgian zoologist and paleontologist Pierre-Joseph van Beneden coined the word mutualism to describe “mutual aid among species,” in other words a symbiosis that is beneficial to both of the involved organisms. (There are other types of symbiosis, too: commensalism, parasitism, competition, …)
Mutualism drives evolution. I think about humanity’s relationship to corn … how the domestication of corn sparked agriculture and had massive impact on how human culture developed. But not only that: it also had a massive impact on how corn developed. In fact corn wouldn’t even exist without the help of humans, since it developed only after generations of selective breeding of a wild grass called teosinte. Teosinte’s symbiotic relationship with another species, humans, impacted the evolution of a new crop. And it was a symbiosis that was also of great benefit for humans.
On a recent early afternoon visit to the Ganna Walska Lotusland in Montecito, California, I followed a guided tour through the gardens. As I pondered one of the information stands in the bromeliad garden, another example of symbiosis in nature was brought to my attention. The piece on the info stand was titled Bromeliad-Frog Mutualism:
The ecosystem inside the water reservoir of a tank bromeliad is incredibly complex. Several hundred species of aquatic organisms can be found including fungi, algae, protozoa, small invertebrates such as insects, spiders, and vertebrates such as frogs, salamanders, and snakes. Frogs use the reservoirs inside tank bromeliads to lay eggs and rear tadpoles. Mosquito larvae serve as good food source for growing tadpoles. The bromeliad benefits from this relationship through the increased uptake of nutrients left by all these living organisms.
But the most obvious symbiotic relationship — at least from the perspective of mankind — is perhaps the preeminent one between humans and plants: plants create oxygen which we humans need in order to live, and humans in turn produce carbon dioxide which the plants need.
To depend on something or somebody else for our survival is beautiful. It’s also natural, and it’s at the core of what it is to be a human being.
Bibliography
- Crombie, James M. and Vernon Herbert Blackman. “Lichens” in Encyclopædia Britannica. 11th. ed. vol. 16. Cambridge: Cambridge University Press. 1910-1911.
- Kropotkin, Peter. Mutual Aid: A Factor of Evolution. New York: McClure, Phillips & Co., 1902.
- McKean, Erin. The New Oxford American Dictionary. 2nd ed. New York: Oxford University Press, 2005.
- Sheldrake, Merlin. Entangled Life: How Fungi Make Our Worlds, Change Our minds & Shape Our Futures. New York: Random House, 2021.