In Japan, the scuticociliates "Orchitophrya stellarum" and another "Orchitophrya" sp. are known to parasitise the gonads of this seastar, especially the males. "O. stellarum" infects testes and feeds on the gonads of various seastar species. It can cause castration and be lethal for "Asterias amurensis" in Japan. Other possible parasites found associated with these seastars are the skeleton shrimps "Caprella astericola", the copepod "Scottomyzon gibberum", the polychaete scaleworm "Arctonoe uittuta", species from the harpacticoid copepods genera "Parathalestris", "Thalestris", "Paramphiacella" and "Eupelite", as well as several unidentified gammaridean amphipods and an unidentified apicomplexan living within it.