Heligmosomoides coils its body around villi, freeing its mouth to graze on host tissue.
Some trematodes are believed to secrete proteases from ventral glands (top) or a tribocytic organ (T, bottom) which digests host tissues that can then be ingested via the mouth or absorbed across the tegument.
Entamoeba histolytica can secrete proteases which erode host tissues. The parasite then engulfs particles.
Intracellular parasites obtain their nutrients from their host cells.
Some, such as Trichinella larvae (L) do not destroy the host cell. The parasite lives in skeletal muscle (M) and transforms infected cells into nurse cells.
Others, however, end up killing the cell after feeding and growing within it. Eimeria feeds within epithelial tissues (E).
Trichuris lives in the lumen of the intestine, but inserts its thread-like esophagus (arrow) into the mucosa of the intestine and feeds there.
