Internal anatomy of the blue mussel (open shell). Organs named from the top and clockwise: posterior adductor muscle, mantle, ganglion, gills, posterior retractor muscles, gonadal tissues (reproductive tissue), byssus, byssal threads, anterior retractor muscle, foot, labial palps, anterior adductor muscle, esophagus (gullet), ganglion, stomach, intestine, heart and anus.
External view of the blue mussel's shell, showing its anterior (umbo), posterior, dorsal and ventral sides, as well as the growth rings and the byssal threads.
