9/13/2006

Unusual Foraging Behaviour of Lumbricus terrestris:
Observations from a garden in Kent, UK. 

Lumbricus terrrestris (the lob worm) is the largest earthworm found in the UK. This species may form a permanent vertical burrow (up to 2m in depth), a key resource for these animals.
 

L. terrestris usually forages at the soil surface, under the cover of darkness, by keeping its tail anchored in its burrow and stretching around in a circle, feeding on dead/decaying plant material and soil.

 
However, observations made by Mr Robert Oseman in his garden in Gravesend in Kent have brought to light an unusual, and previously unrecorded, foraging behaviour for this species.

 
On several occasions Mr Oseman had noticed what he termed “worm trails” (wet marks) on pieces of slate, leading into his garden pond at night. Curious to know what was making these trails, he began to make detailed observations of the pond and immediate vicinity.  The pond contains free floating parrots feather plants (Myriophyllum spp.), strands of which he noticed were being drawn towards the edge of the pond and had been dragged out of the water near to the “worm trails”.   Mr Oseman was intrigued by this sighting and suspected that earthworms were responsible. His suspicions were confirmed when he observed an earthworm dip into the pond, emerge with a piece of pond weed in its mouth and drag the weed backwards into its burrow.

 
Having solved the mystery Mr Oseman wanted to find out exactly which species of earthworm were responsible so he contacted Dr Kevin Butt at the Earthworm Research Group. Similarly intrigued, Drs Butt and Chris Lowe visited Mr Oseman’s pond where they located several earthworm burrows. The burrows appeared to run close to the outside of the plastic pond liner. Application of a vermifuge (mustard powder in water) to one of these burrows yielded an adult earthworm ( 6 g in weight) that was washed, identified as L. terrestris and returned to it’s burrow.