AbstractThe NH₂-N content of the various parts of the burrow and of the gut-content of Arenicola marina from the Danish Waddensea has been compared with the vertical distribution of NH₂-N in the substratum in which the worm occurs. Calculations based on these studies, together with a review of the literature, indicate that in the locality investigated Arenicola is a deposit-feeder and that the suspension-feeding mechanism proposed by Kruger in recent articles cannot cover the food requirements of the worm.