Filtering comb areas were greatest forDaphnia pulexandD. similis, and least forD. parvula, relative to body length. The slopes of the regressions of comb area body length were different from expected (based on simple geometry) forD. pulexandD. similis. Filtering rates of these daphnids in suspensions of inert sediment particles were less related to comb areas than they were to the gut filling capacity of these particles.