Site of particle selection in a bivalve mollusc

Bivalve molluscs form dense populations that exert profound effects on the particle loads and phytoplankton composition of coastal waters 1 . It has long been known that bivalves can select among different particle types, including selecting against those of poor nutritional value 2 , 3 , 4 , 5 , but because of difficulties in observing particle transport processes in the pallial cavity in vivo , the mechanism of selection was not known. We now use a combination of video endoscopy 6 and flow cytometry 7 to show that oysters can select living particles from non-living detritus on the gills. Our methods could aid the study of suspension feeding in many animal groups.