filter feeder

noun

1. an aquatic animal that feeds on particles or small organisms strained out of water by circulating them through its system: includes most of the stationary feeders, as clams, oysters, barnacles, corals, sea squirts, and sponges.

1. An aquatic animal, such as a clam or sponge, that feeds by filtering tiny organisms or fine particles of organic material from currents of water that pass through it.