Southern Research Station

Title:  Grunting for worms: reactions of Diplocardia to seismic vibrations

Author: Callaham, M.A.

Date: 2009

Source: Biology Letters 5:16-19. (updated citation)

Description: Harvesting earthworms by a practice called 'worm grunting' is a widespread and profitable business in the southeastern USA. Although a variety of techniques are used, most involve rhythmically scraping a wooden stake driven into the ground, with a fiat metal object. A common assumption is that vibrations cause the worms to surface, but this phenomenon has not been studied experimentally. We demonstrate that Diplocardia earthworms emerge from the soil within minutes following the onset of grunting. Broadband low frequency (below 500 Hz) pulsed vibrations were present in the soil throughout the area where worms were harvested, and the number of worms emerging decreased as the seismic signal decayed over distance. The findings are discussed in relation to two hypotheses: that worms are escaping vibrations caused by digging foragers and that Worms are surfacing in response to vibrations caused by falling rain.

Keywords: earthworm, vibration, escape, rain, moles

View and Print this Publication (268.76 KB)

Publication Notes: 

• We recommend that you also print this page and attach it to the printout of the article, to retain the full citation information.
• This article was written and prepared by U.S. Government employees on official time, and is therefore in the public domain.
• You may send email to pubrequest@fs.fed.us to request a hard copy of this publication. (Please specify exactly which publication you are requesting and your mailing address.)

 Get the latest version of the Adobe Acrobat reader or Acrobat Reader for Windows with Search and Accessibility

Citation

Callaham, M.A.  2009.   Grunting for worms: reactions of Diplocardia to seismic vibrations.   Biology Letters 5:16-19. (updated citation).