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 thln cuvettes in the laboratory. Three-dimens~onal burrows of 81 shrlmps were used to describe the 3-dimensional burrow architecture. In total, 41 shrimps made 2-dimensional burro\vs in cuvettes tailored to their body widths. Development of 8 burrows over time was registered by regularly mapping burrow outllnes and sediment surface levels. Excavation velocities and s e d~m e n t expulsion rates were denved 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-' durlng the initial stage of bul-row development. The length ~ncl-ease levelled off during the completion of the first and second U-tubes to 5.6 r 1.8 mm h-' In~tial sediment expulsion rates up to 15 0 cm3 d.' were established. The average sedim~.nt expulsion rate was 1.080 t 0.096 cm" d.' Extrapolation to a yearly dry welght (dry I\?) sediment turnover, including population density and water temperature effects, resulted in an estimate of 15.5 + 2.7 kg dry wt m-' yr-l, equivalent to d 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.