Sonic Patterns III: Sounds and Vibrations from Soils - Soundscape Ecology: Principles, Patterns, Methods and Applications - page 211

Fig. 8.3 The grunting technique used to capture Diplocardia earthworms. In ( a ), the authors
demonstrate the use of this technique. ( b ) The tools used to produce vibration into the soil.
( c ) Oscillogram and spectrogram produced by the seismic vibration recorded at 1.8 m from the
stake. ( d , e ) Horizontal and vertical geophone recordings, respectively (From Catania 2008 )
Two opposed hypotheses have been discussed by Mitra et al. ( 2009 ) to explain
the grunting: worms emerge from the soil in natural conditions to escaping the
vibrations caused by digging foragers, or emerge as result of the vibrations pro-
duced by falling rain.
Catania ( 2008 ) has excluded the idea that worms emerge after human grunting
because the vibrations copy the vibration of rainfall (Fig. 8.3 ). This author ascribes
the emergence of worms from soil to vibrations resembling mole-like digging in the
attempt to escape mole predation, considering that humans are playing the role of
“rare predators.”
Vibration is extensively used by social insects such as bees and ants, but other
social insects use vibration in food recruitment, mating, and antipredatory signals.
Food recruitment is well documented in treehoppers, in sawflies, and in tortoise