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Eavesdropping on life underground

Listening out? Arterra/Universal Images Group/Getty

The ground beneath our feet is “home to more life, and more diverse life, than almost any other place on Earth”, says Ute Eberle in Knowable Magazine. In a single cup of dirt researchers have counted “100 million life forms”; underground denizens range from microscopic bacteria to earthworms several metres long. To better understand this “complex and cryptic world”, biologists have begun sticking microphones into the ground to eavesdrop. As it turns out, “every soil organism produces its own soundtrack”.

Larvae click as they munch on roots. Worms rustle as they inch through tunnels – as do plant roots growing through the soil. Some noises are signals: mole rats communicate by banging their heads or feet against tunnel walls; leafcutter ants make a racket if they get buried in cave-ins, letting their nestmates know where to dig them out. But being noisy can also be deadly. When birds hop across lawns with their heads cocked, they are likely to be “listening for worms below”.

Trying to describe these sounds isn’t easy. “There [is] thrumming and chirring and scraping,” says Marcus Maeder, a Swiss acoustic ecologist. “You need a whole new vocabulary.” And who knows what mysteries will emerge as we listen in more. Life underground is a “black box”, says Uffe Nielsen, a soil biologist at Western Sydney University. “As we open it, we realise how little we know.”

Read the full piece here.