Also found in: Dictionary, Medical, Wikipedia.
filter feeder[′fil·tər ‚fēd·ər]
an aquatic animal that feeds on minute planktonic organisms or suspended particles, which it filters from the water. Active filter feeders, including many crustaceans, tunicates, and whalebone whales, draw water through external or internal filtration organs by moving their cilia or extremities or contracting their muscles. Passive filter feeders make use of water currents. For example, sea lillies have branches with numerous feathery outgrowths, which they spread in the direction of the current, creating a complex, immobile filtration network. Filter feeders often combine suspension feeding with deposit feeding. Filter feeders include many marine and freshwater species. Some species, for example, marine mussels, play an important role in purifying sea water of slime in coastal regions.