Moles, not magic, make worm 'grunting' work

[bassFishingWNY]

http://news.yahoo.com/s/ap/20090612/...Vzbm90bWFnaQ--

By BRENDAN FARRINGTON, Associated Press Writer Brendan Farrington, Associated Press Writer – 17 mins ago
TATE'S HELL, Fla. – Gary Revell gets up every morning before sunrise, heads into the woods and grunts.
Not because it's so early. It's the term for coaxing worms from the ground by the hundreds to be scooped up and plopped in a tin can until he can sell them for fishing bait.
He pounds a two-foot wooden "stob" or stake into the earth and rubs it with a 10-pound piece of flat iron. The vibration or "grunting" causes worms to panic, and they wriggle from the ground. For years it was just a guess why.
Vanderbilt University biological sciences professor Ken Catania wanted to expand on a theory put forth by Charles Darwin that worms may sense moles are pursuing them if the ground trembles.

I used to do near the same thing when young, but a metal rod, and hooked to a crank . Turn the crank, up came the worms. I though it was a generator, and sent a shock wave into the ground, that made them come up?
At 65 years old, little old for grunting anyway! But sounds neat!!