By using light and scanning electron microscopy,unique characteristics in the morphology,histology,and growth patterns of the lateral line system was observed in the Pufferfish,Takifugu obscures.The lateral line system of T.obscurus is consisted of the main lines and accessory lines(and accessory neuromasts).The former includes supraorbital,infraorbital,postotic,mandibular,preopercular,and supratemporal lines on the head,and dorsal,and ventral trunk lines on the body.The later includes rostral accessory,infraorbital accessory,mandibular accessory,posteriodorsal mandibular accessory,and posterodoral supraorbital accessory lines,and ventral supratemporal accessory,dorsal supratemporal accessory,posterior preopercular accessory,trunk accessory and caudal accessory neuromasts.There are over one thousand neuromasts,the mechanoreceptive organs,in the lateral line system of T.obscures.They are uniquely located at the top of the individual tubercle,and distribute in the superficial grooves which are arranged according to the above topographic line patterns.Each of the neuromast consists of sensory hair cells,supporting cells and surrounded by mental cells.Sensoryhair cells stay in circular at the centre of the neuromast.Each of them has one kinocilium and dozens of stereocilia on the top.Even though there is no real canal system in the T.obscurus,the patterns of the line distribution and the growth of neuromasts that indicate that the lateral line system in the T.obscurus still have two mechanoreceptive systems such as in other teleoste fishes.The neuromasts in the main lines may be homologues of the canal neuromasts and the neuromasts in the accessory lateral line and accessory neuromasts may be the real superficial neuromasts.