Daphnia are Tangential Flow Filter Feeders

Since ever, Daphnia have been characterized as dead-end filter-feeders where water passes through the setae and setules while algae get caught on this mechanical filter and are then transported to the crushing mandibles. Given that all feeding appendages are enclosed by the carapace a mechanism like the one in calanoid copepods was not expected. With high-speed video and special optical techniques, we observed how water flows through the carapace cavity during the creation of the feeding current. The observations point to tangential flow filtration with high shear micro-environments that allow incoming algae a direct way to the space in front of the mandibles. Results will be shown in videos.