Abstract: Larval sea cucumber(Apostichopus japonicus) was cultured in six 30-L plastic tanks at a rate of 303 individuals /L and fed algal mixture of Dunaliella salina and Chaetoceros müelleri for 10 days at water temperature of 21℃~22 ℃.The various 10 cm×10 cm settlements including rugged polyethylene planks,flat polyethylene planks,and with 500 um or 250 nm groove surfaces and different colors(green,black,yellow,red,and blue) were positioned in the tanks just before doliolaria stage to evaluate the effects of settlement types,roughness and surface color on attachment of larval sea cucumber.It was found that there were 68.76% more sea cucumber larvae on the rugged polyethylene planks than that on the flat polyethylene planks,very significantly different from the flat polyethylene planks(t=7.131〉2.804,df=23).The attachment of the larvae was showed to increase with increase in the roughness on the settlements,and the amount of larvae on the smooth polyethylene planks was found to be 267.42% higher than that on the planks with 500 um groove surfaces(with significant difference) and 32.34% higher than that on the plankes with 250 nm groove surfaces(without significant difference).There were more sea cucumber larvae on the red and black planks than that in the control groups(without color),84.52% higher on the red plates and 37.49% on the black plates(with very significant difference).Significant reduction in the larvae number was observed on the day 5 after the attachment of the larvae which had only one tube foot,even though the attachment was found increase as the larval culture proceeded.The results were discussed in detail from attachment mechanism including environment,tube foot development of the larvae and functions of a settlement.

Key words: sea cucumber(Apostichopus japonicus), larva, attachment, settlement, development