filter feeder

Krill feeding in a high phytoplankton concentration (slowed by a factor of 12)

Filter feeders are aquatic animals that acquire nutrients by feeding on organic matter, food particles or smaller organisms (bacteria, microalgae and zooplanktons) suspended in water, typically by having the water pass over or through a specialized filtering organ that sieves out and/or traps solids. Filter feeders can play an important role in condensing biomass and removing excess nutrients (such as nitrogen and phosphate) from the local waterbody, and are therefore considered water-cleaning ecosystem engineers. They are also important in bioaccumulation and, as a result, are indicator organisms.