The architecture and development of the burrows of the endobenthic shrimp Callianassa subterranea from the central North Sea were studied in sediment-filled containers and thin cuvettes in the laboratory. Three-dimensional burrows of 81 shrimps were used to describe the 3-dimensional burrow architecture. In total, 41 shrimps made 2-dimensional burrows in cuvettes tailored to their body widths. Development of 8 burrows over time was registered by regularly mapping burrow outlines and sediment surface levels. Excavation Velocities and sediment expulsion rates were derived from changes in the burrow outlines and sediment surface levels on the maps. The total tunnel length increased at a rate of 23.4 +/- 6.0 mm h(-1) during the initial stage of burrow development. The length increase levelled off during the completion of the first and second U-tubes to 5.6 +/- 1.8 mm h(-1). Initial sediment expulsion rates up to 15.0 cm(3) d(-1) were established. The average sediment expulsion rate was 1.080 +/- 0.096 cm(3) d(-1). Extrapolation to a yearly dry weight (dry wt) sediment turnover, including population density and water temperature effects, resulted in an estimate of 15.5 +/- 2.7 kg dry wt m(-2) yr(-1), equivalent to a 1.2 cm layer. Samples of burrow lining, expelled sediment and unprocessed sediment did not show changes in grain size distributions or organic content due to manipulation or processing by C. subterranea. Burrow development experiments carried out in enriched seawater systems did not reveal consistent effects of particulate organic matter (POM) on sediment expulsion rates or on the composition of processed or unprocessed sediment.