Consumption of Food Particles: Mechanics of Grazing and Predation
Most consumers in the classic food webs obtain most of their nutrition by eating particulate foods, which are obtained in various ways. Food particles may be consumed by engulfing the prey with pseudopods, as in, for example, amoebas, radiolarians, and foraminiferans. Suspension feeders collect food particles via different ways: ciliates, sponges, bivalves, many annelids, and brachiopods create feeding currents by the beating of cilia or appendages to bring food to the animal; tunicates and some gastropods produce mucus sheets that are used as sieves or sticky surfaces to capture food; copepods and barnacles use setae- and setule-bearing appendages to capture particles much smaller than the consumer; and some fish strain particles by passing water through gill rakers, and whales use baleen for the same purpose. Deposit feeders, such as many sea cucumbers, bivalves, polychaetes, and shipworms, collect and ingest sediments that contain food particles. Raptorial feeders (gastropods, cephalopods, crustaceans, cnidarians, turbellarians, polychaetes, fish, birds, turtles, snakes, and some mammals) capture and consume food particles that are relatively large compared to the size of the consumers.