Cladosiphon okamuranus

Thallus string-like, cylindrical, soft, fleshy-gelatinous, slimy, solid in young branches and hollow in old parts, brown or greenish-brown, forming interwoven clumps 20-30 cm high. Main axes 1.0-1.5 mm diam. Branching irregular, alternate, with short or long branches. Plurilocular sporangia clavate, scattered over the surface of thallus. Growing on sandy bottom with stones, dead coral fragments, intertidal to subtidal (at depth range from 0 to 19 m), in calm shores.

Common on south Islands of Ryukyu Archipelago (Okinawa, Ishigaki, Iriomote, etc.). The edible seaweed has been cultivated in Kagoshima and Okinawa Prefectures on nets (crop amount to 20000 ton fresh weight per year), harvested by water pump, and used mainly for food, in medicine and for alginate production.