animals dwelling in bottom sediments of seas, rivers, lakes, and ponds. They include many mollusks, echinoderms, segmented and round worms, insect larvae, some fishes, stone borers (some sponges, mollusks, sea urchins), and wood borers (the mollusk Teredo, some crustaceans). Infauna is categorized by the type of sediment in which it dwells: pelophilic (in ooze), psammophilic (in sand), lithophilic (in stones), and argillophilic (in clay). Most species of infauna feed on detritus. Certain forms of infauna carry out daily and seasonal vertical migrations. Infauna is important as a source of food for fishes that feed on bottom-dwelling animals (benthos).