Presence of compounds containing iron in the digestive system.
D000818:Animals; D003445:Crustacea / Q000378:metabolism*; D004064:Digestive System / Q000166:cytology / Q000378:metabolism*; D005293:Ferritins / Q000378:metabolism; D006433:Hemocyanins / Q000378:metabolism; D006485:Hemosiderin / Q000378:metabolism; D006651:Histocytochemistry; D007501:Iron / Q000378:metabolism*; D012119:Respiration; D013053:Spectrophotometry
D005293:Ferritins; D006485:Hemosiderin; D006433:Hemocyanins; D007501:Iron