Bopyroides hippolytes (Kröyer 1838)

In Great Britain and/or Ireland:
Animal / parasite / ectoparasite
Bopyroides hippolytes ectoparasitises branchial cavity of Hippolyte varians
Other: unusual host/prey

Animal / parasite / ectoparasite
Bopyroides hippolytes ectoparasitises branchial cavity of Spirontocaris
Other: major host/prey

How to Distinguish from Similar Species: Argeia pugettensis lives on shrimp in family Crangonidae, and the female has well developed pleopods and uropods. Other bopyrids are found on thalassinids, galatheids, or hermit crabs, or on the dorsal side of the thorax or underside of the abdomen.

Geographical Range: North Pacific Ocean, Bering Sea, Arctic Canada, Greenland, eastern North America, Norway, and Britain. On our coast found down to southern California

Depth Range: Intertidal and subtidal.

Like all Epicaridean isopods, this species is parasitic on other crustaceans. Epicaridean females tend to be of distorted shape with most appendages reduced or absent, while the males, which usually are found on the females, are small and symmetrical. Bopyroides hippolytes has separate sexes at least as adults, and the male is smaller and more symmetrical than is the female. They are ectoparasitic in branchial chambers of shrimps of families Hippolytidae and Pandalidae. Females are less asymmetrical than in some other bopyrids, with all pereonites distinct, with 5 pairs of nearly equal oostegites and 7 pairs of pereopods. The female usually has 6 distinct pleonites but these either lack or have only rudimentary lateral plates. Her pleopods are also missing or reduced to tubercles. She has no uropods. Her brood pouch is open. The pleonites of the male are fused.

Biology/Natural History: Isopods of family Bopyridae live parasitically on the gills of other crustaceans such as shrimp. Typically a large female and a smaller male are found together on the same individual. Usually they parasitize only one side of the host--rarely is a shrimp parasitized on both sides by bopyrids. The females are usually asymmetrical, while the males are symmetrical. They seem to enter the shrimp early in the shrimp's life and remain through molts. In Pandalopsis dispar they appear to retard growth and delay sex change in the host shrimp. Bopyrids develop to young larvae within the mother's marsupium formed by her oostegites. In this individual, the mother's ventral side was pressed against the medial surface of the gill cover instead of against the gill itself. The oostegites did not overlap, but simply formed a wall around the eggs while the host's gill cover formed the floor of the chamber the eggs were within. When I removed the female from the gill chamber her eggs mostly spilled out because they were not fully enclosed by the ooostegites. The first larval stage is 2-3.5 mm long and is called an "epicaridium". It has six free pereonites, each of which bears a pair of subchelate pereopods which it uses to attach to an intermediate planktonic host such as a copepod. On that host it molts into a "microniscus" or "microniscum" larva, then later to a "cryptoniscum" or "cryptoniscus", which is up to 7 mm long and has a 7th pereonite. At this stage it releases from the intermediate host, becomes benthic, and finds its final crustacean host. Within the host it metamorphoses into either a large, asymmetrical female or into a smaller, symmetrical male. The adult form is called a "bopyridium".

This isopod is parasitic on several families of shrimp, especially members of families Hippolytidae and family Pandalidae, but not on members of family Crangonidae.

Saguenay Fjord; southern Gaspe waters (Baie des Chaleurs, Gaspe Bay to American, Orphan and Bradelle banks; eastern boundary: eastern Bradelle Valley); Cobscook Bay to Cape Hatteras

ectoparsite of invertebrates; circalittoral of the Gulf and estuary