Lug worm castings on the beach

We saw these coiled piles scattered on the beach along the east coast of Scotland a few days ago. Their appearance is reminiscent of earth worm castings, and I found out that they are indeed castings of a worm: the lug worm, Arenicola marina. Usually there is a blow hole a few inches away from each pile. The hole leads down to the mouth of the worm, which continually ingests sand, and digests the bacteria in the sand.  The sand particles are excreted as castings from the rear end of the worm, which sits just below the surface of the ground. The coin is about an inch in diameter

The odd thing about the castings we found was that there were no blow holes associated with them. I am told that this might be because the sand was too fluid (fine and wet), for the holes to persist. For some great photos of blow holes and castings in abundance, and some great information on this species, see:
http://natureinfocus.wordpress.com/2011/07/10/lug-worms-at-whiteford-sands/

Janet
http://ouroneacrefarm.com/