Parasite Bopyroides hippolytes
Taxonomy Arthropoda, Crustacea, Malacostraca, Isopoda
Hosts Northern shrimp (Pandalus eous), humpy shrimp (P. goniurus), Aesop shrimp (P. montagui), (Eualus spp.), (Spirontocalis spp.), (Pandalopsis aleutica), etc.
Infection site Branchial chamber
Clinical sign Infected shrimps exhibit a swelling of the carapace caused by the presence of the parasite in the gill chamber (Fig. 1).
Parasitology Bopyroides hippolytes is a parasitic crustacean, infecting the branchial chamber of shrimps such as Pandalus spp. (Boyko, 2004). Dioecious. The body of female (ca. 8 mm in length) is asymmetric and oval, while that of male (ca. 2 mm) is symmetric and elongated (Fig. 2). Male and female habit in the branchial chamber on one side, where the male parasitize the female. Generally, the free-living larvae (epicardium stage) hatched from eggs, become the microniscium larvae, which attach on the surface of free-living copepods. They metamorphose into the adult (cryptoniscium) on the body surface of the shrimp. However, the life cycle of B. hippolytes is unknown in detail (Shiino, 1969).
Pathology Pathogenicity to host shrimp is considered to be negligible.
Health hazard Since this parasite is not infectious to human, it is harmless in food hygiene. This disease does not influence on texture of the shrimp.
Diagnosis This parasite can be visually observed in the gill chamber.
References Boyko, C. B. (2004): The bopyridae (Crustacea: Isopoda) in Taiwan. Zool. Studies, 43, 677-703.

Shiino, S. (1969): Suisan musekitsui dobutsu gaku. Baifukan, Tokyo, 345pp. (In Japanese)
(Photos by K. Ogawa(2))

Fig. 1. Swellings of the carapace of shrimps caused by B. hippolytes.

Fig. 2. Male (left) and female (right) of B. hippolytes.