Blood flukes have a double outer membrane.
D000818:Animals; D001769:Blood / Q000469:parasitology; D000939:Epitopes; D005260:Female; D005399:Fishes / Q000469:parasitology; D007109:Immunity; D008297:Male; D008854:Microscopy, Electron; D012547:Schistosoma / Q000648:ultrastructure; D014200:Trematoda / Q000276:immunology / Q000648:ultrastructure*; D014426:Turtles / Q000469:parasitology
D000939:Epitopes