Worm Grunting Mystery Solved…by Darwin

By Nina Bai | October 14, 2008 6:38 pm

wormMoles can eat their own weight in worms each day. But they’re no match for human worm grunters—also known as worm snorers, fiddlers, or charmers— who can collect thousands of worms each day, selling them for bait. Worm grunting involves thrusting a stick into the soil and rubbing it with a piece of steel to generate vibrations that send earthworms fleeing to the surface. It’s quite popular in the southeastern U.S.— but until now, no one really understood why it worked.

Ken Catania, a mole expert at Vanderbilt University and MacArthur genius award winner, made the connection between moles, worms, and human grunters. The humans are fooling the worms by unknowingly imitating the sound of a burrowing mole. The worms instinctively surface (faster than you’d think) because moles generally stay underground when foraging.

In Catania’s paper on this topic, he gives props to Darwin, who made the same hypothesis more than a century ago. “It is often said that if the ground is beaten or otherwise made to tremble worms will believe that they are pursued by a mole and leave their burrows,” Darwin wrote in The Formation of Vegetable Mould Through the Action of Worms. Through trial and error, Darwin also observed that worms don’t respond to the sounds of whistles, bassoons, pianos, or human shouting. Which proves yet again that Darwin knew everything.

Related Content:

DISCOVER: The Electric Mole
Discoblog: Worms Are Picky Ejaculators

Image: flickr/ Dodo-Bird

MORE ABOUT: animals, Darwin, moles, worms
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