is found in a wide range of sediment types. In general, the relative occurrence increases in proportion to the median grain size of the sediment up to a maximum relative occurrence of over 60%, which is reached when the median grain size is 450 to 550 μm. Gastrosaccus spinifer
does not display an absolute preference for sediments with a specific mud level. However, the species is absent in sediments with a mud content exceeding 70%.