In southwestern Africa's Namib desert, the lack of rainfall keeps grass sparse. But in some areas, mysterious rings of grass with bare centers appear and thrive. Now scientists have discovered these so-called fairy circles are indeed created by wee little creatures—termites. The work is in the journal Science. [Norbert Juergens, The Biological Underpinnings of Namib Desert Fairy Circles]
Many organisms live in and around fairy circles, which range from one to 50 meters in diameter and persist for decades. But scientists found only one species consistently inhabiting even the youngest fairy circles. The sand termite Psammotermes allocerus is thus the most likely culprit behind the rings.
How do termites make fairy circles? Living grass sucks up rainfall and loses the liquid to evaporation. But when termites cluster together, feeding on and destroying vegetation, they leave a roughly circular bare patch that stores more water than the surrounding soil. The fairy circle thus acts as a water reservoir for the sand termites, the grasses around the edge and other thirsty organisms.
So maybe we should start calling these rings “termite circles.” Nah—sounds a bit wooden.
[The above text is a transcript of this podcast.]