microfilterfeeding

Microfilterfeeding is a feeding strategy in which organisms extract microscopic food particles from water using specialized structures that create flow and capture particles in the micrometer size range. It is employed by a diverse set of taxa, including single-celled ciliates and flagellates, sponges (via choanocytes), many crustaceans such as copepods and cladocerans, and various mollusks and polychaetes. Particles typically consumed are tiny algae, bacteria, and detrital matter.

Most microfilter feeders generate a water current with ciliary action, flagellar beating, or muscular pumping to bring water to a filtration surface. Food particles are captured on surfaces such as collar cell filters, mucous nets, or filtering membranes, and are then ingested or phagocytosed. Particle size and shape influence which items are retained and ingested, creating a level of selectivity within the microfiltered fraction of the plankton or particulates.

Ecological roles of microfilter feeders include regulating microbial communities, transferring energy up the food web, and contributing to nutrient cycling. They are foundational in many aquatic systems, serving as both consumers of microorganisms and as prey for larger zooplankton and fishes. Environmental factors such as particle concentration, water clarity, temperature, and viscosity affect filtration efficiency and energy budgets. Methods for studying microfilter feeding commonly involve measurements of clearance or filtration rates and assessments of particle-size selectivity.