A. planci was attracted to AA and LA at concentrations greater than 2 mg per dish (200 ml jelly). in the aquarium (5=3=3 m.) and was never attracted to control jelly (Table 1) Commercially available AA and LA exhibited the same chemoattractive activity for the sea star (Fig. 5) at the same concentration as the compounds obtained from the viscera. The attractive activity of AA was equal to that of LA, and an increase in the chemoattractive activity by mixing them was not observed. Interestingly, other unsaturated fatty acids such as eicosapentaenoic acid, docosahexaenoic acid, and linoleic acid showed no activity at the concentration of 50 mg per dish in the aquarium (Table 1)