Cymothoids (Crustacea, Isopoda), obtained from the stomach contents of a finless porpoise Neophocaena phocaenoides (Cetacea: Phocoenidae) in Japan

Abstract

Three ovigerous females and a male of the ectoparasitic isopod Mothocya sp. were found in the stomach contents of a female finless porpoise Neophocaena phocaenoides entangled in a drift net at Mikawa Bay (34°72'N; 137°06'E), Japan. The present finding represents the first record of the genus Mothocya from N. phocaenoides (not as host). The parasites seemed to infect the branchial cavities of host fishes. Moreover, the fishes would be eaten by the finless porpoise. When isopods were found in the stomach contents of the piscivorous whales, we need to distinguish between parasitic and free-living isopods in order to get accurate results of their food habits.