Measured settling velocities of fecal pellets produced by Amphicteis scaphobranchiata, a deposit-feeding subtidal polychaete worm, are analyzed to determine the effects of pellet shapes and to arrive at improved formulae for predicting settling rates of fecal pellets in general. Drag coefficients calculated from the measured settling velocities and pellet densities decrease with increasing Reynolds numbers, the trend roughly paralleling the drag-coefficient curve for spheres but having higher values due to the nonspherical shapes of the pellets. No clear dependence could be found on the pellet shapes, however, when the shape is expressed as pellet elongation (length/width). Comparisons are also made between the measured settling velocities and equations for the prediction of settling of spheres, the relationships between the two serving as the basis for improved equations for the evaluation of settling velocities of fecal pellets of diverse origins.
Komar, Paul D., and Gary L. Taghon. 1985. "Analyses of the settling velocities of fecal pellets from the subtidal polychaete Amphicteis scaphobranchiata." Journal of Marine Research 43, (3). https://elischolar.library.yale.edu/journal_of_marine_research/1789