Abstract
Abstract: For a year we investigated prey preference of a vermivorous opisthobranch, Pupa strigosa, at the mouth of the Inari River, Kagoshima Bay, Japan. Pupa strigosa were sampled twice a month from September, 1999, to October, 2000, at depths of 5 to 20 m. Gut contents were present in 253 of the 382 collected specimens, and the polychaete prey were identified from the setae and jaws found in the guts.The opisthobranchs fed on benthic polychaetes belonging to seven families. Their diet changed both with season and with increasing body size of the opisthobranchs. The shell size was small in autumn, when most individuals fed on dorvilleid polychaetes. Later they fed on glycerid, nereidid, spionid, pilargid, lumbrinerid, and sabellid polychaetes. The prey included chiefly free-living or crawling and carnivorous or omnivorous polychaetes, but rarely sessile forms.
