 "Didemnum vexillum" appears to be native to Japan, where it was recorded in Mutsu Bay in 1926.It is still common there and, as well as growing on rock surfaces and seagrasses ("Zostera"), it grows as a fouling organism on cultured bivalves, net cages, pilings and other man-made structures.Its depth range is from the intertidal zone down to a depth of about .