The role of the burrow funnel in feeding processes in the lugworm Arenicola marina (L.)

Lugworms (Arenicola marina) are typical marine deposit feeders (Jumars, 1993). Labile organic matter, notably bacteria, meiofauna and diatoms, is digested from the large volumes of nutritionally-poor sediment which are processed by the gut. Detritus is not evidently digested. However, it is trapped in the funnel of the burrow, and probably enhances the nutritional quality of the food by providing a substrate for bacterial growth. The worm's irrigation current is also important because, if the headshaft of the burrow is blocked so that the current no longer reaches the funnel, there is a decrease in the numbers of bacteria there.