The parasitic isopods of Crustacea

The Epicaridea
Bopyrids live in the gill cavity or on the carapace of their crab and shrimp hosts. The parasites often distort the carapace of their hosts into a characteristic bulge. This bulge has even been observed in various fossilized hosts.
Entoniscids are unusual internal parasites that live in the hemocoel of their crab hosts. One species is found in a snapping shrimp, Synalpheus sp. Adult females of these parasites bear little morphological resemblance to any free-living isop ods.
Dajids are external parasites of krill (euphausiids and mysids) and midwater shrimp. The parasites look like hitchhikers on the backs of their hosts. They are often mistaken as fleshy growths.
Members of the super-family Cryptoniscinae are cryptic parasites and hyperparasites of crustaceans, including barnacles, ostracods, mysids, amphipods, and isopods. In the future, all of the members of this taxon will be included here. Until then, an excellent account of the family is given in Nielsen, S.O. & Stromberg, J.O. 1965. A new parasite of Cirolana borealis Lilljeborg belonging to the Cryptoniscinae (Crustacea Epicaridea). Sarsia 18: 37-64.

There are several families represented in the group:

  • Hemioniscidae

    • Hemioniscids are parasites of cirripede barnacles.

  • Cyproniscidae

    • Cyproniscids are parasites of free-living isopods.

  • Asconiscidae

    • The single species, Asconiscus simplex G.O. Sars, 1899, is parasitic on the mysid Boreomysis arctica.

  • Crinoniscidae

    • The single species, Crinoniscus equitans Pérez, 1900, is a parasite of the cirripede barnacle Balanus perforatus.

  • Podasconidae

    • This family is represented by Podascon and Parapodascon. They are parasites of amphipods.

  • Liriopsidae

    • Liriopsids are hyperparasites of rhizocephalan barnacles and parasites of other symbiotic crustaceans. The adult females fo this family bear little resemblance to free-living isopods. The developing larvae give clues to their taxonomic affiliations.

  • Cabiropsidae

    • Cabiropsids are parasitic on free-living isopods and hyperparasitic on other epicaridean isopods. The family may also include a few parasites of cumaceans.

For more information on isopods go to Keys to the Isopods or the Smithsonian's Isopoda bibliography.

For Arthropods in general go to Arthropods

For more information on the phylogeny and systematics of Crustacea go to Phylogeny of the Crustacea

Acknowledgements Back to Jeff's Home Page


Entoniscid isopods are unusual internal parasites of brachyuran and anomuran crabs. One species has also been reported from an alpheid shrimp. The parasites typically live in the hemocoel of the host and communicate externally via a small pore that f orms through the exoskeleton of the host. In one host species, a pagurid, the chitinized pore occurs in the eyestalk.


Female entoniscid Male entoniscid epicardium larva
Female entoniscid (Cancrion australiense) Male entoniscid Epicardium larva (6th pereopd)

This list is organized alphabetically by genus with the type species in bold print.

Each entry is given as: Genus species Authority, year --- hosts

Click here for a reference list of the Authorities and additional citations for the Entoniscidae

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Authorities and citation list for the Entoniscidae

Chaix, J.C., & Veillet, A. 1981. Entonisciens nouveaux des cotes de France. II. Portunion bourdoni sp. nov. parasite d'Acanthonyx lunulatus Risso. Bulletin de l'Academi et de la Societe Lorraines des Sciences 20: 7 1-81.

Codreanu, R., Codreanu, M., & Pike, R.B. 1960. Sur un nouveau type d'Entoniscien, Diogenion vermifactus n.g. n. sp., parasite du Pagure Diogenes senex Heller de la mer Rouge. Comptes Rendus Hebdomaires de s Seances de l'Academie des Sciences 251?: 439-441

Coutiere, H. 1908. Sur le Synalpheion giardi, n. gen., n. sp., Entoniscien parasite d'un Synalphée. Comptes rendus hebdomaires des Seances de l'Academie des Sciences 146: 1333-1335.

Demassieux, C. & Viellet, A. 1982. Entonisciens nouveaux des cotes de France. I. Entionella eriphiae sp. nov. parasite d'Eriphia spinifrons. Travaux de la Station biologique Roscoff 28: 131-147.

Fraisse, P. 1878. Entoniscus cavolinii n. sp. nebst Bemerkungen uber die Umwandlung und Systematik der Bopyriden. Arbeiten Zool. Institut Würzburg 4: 382-440.

Giard, A. & Bonnier, J. 1886. Sur le genre Entione Kossman. Comptes Rendus Hebdomaires des Seances de l'Academie des Sciences 103: 645-647. Several genera named, but no figures.

Giard, A. & Bonnier, J. 1887. Contributions a l'étude des Bopyriens. Travaux de l'institut zoologique de Lille et du laboratoire de zoologie maritime de Wimereux 4: 1-272.

Hartnoll, R.G. 1960. Entionella monensis sp. nov., an entoniscid parasite of the spider crab Eurynome aspera (Pennant). J. mar. Biol. Assoc. U.K. 39: 101-107.

Hartnoll, R.G. 1965 A new entoniscid from Jamaica (Isopoda, Epicaridea). Crustaceana 2?: 45-52.

Kossman, R. 1881. Die Entonisciden. Mitteilungen Zoologischen Station Neapel 3: 149-169.

Miyashita, Y. 1940. On an entoniscid with abbreviated development, Entoniscoides okadai, n.g., n. sp. Annot. Zool. Japon. 19(2) 149-157.

Miyashita Y. 1941. Observations on an entoniscid parasite of Eriocheir japonicus de Haan, Entionella fluviatilis n.g., n.sp. Japanese Journal of Zoology 9: 251-267.

Müller, F. 1862. Entoniscus porcellanae, eine neue Schmarotzerassel. Archiv für Naturgeschichte 1: 10-18

Müller, F. 1871. Bruchstücke zur Naturgeschichte der Bopyriden. Jenaische Zeitschrift für Naturwissenschaft 6:53-73.

Muscatine, L. 1956. A new entoniscid (Crustacea: Isopoda) from the Pacific coast. J. Wash. Acad. Sciences 46 (4): 122-126.

Pearse, A.S., & Walker H.A. 1939. Two new parasitic isopods from the Eastern Coast of North America. Proc. U.S. National Museum 87(3067): 19-23.

Reinhard, E.G. 1945 Paguritherium alatum n.g., n.sp., an entoniscian parasite of Pagurus longicarpus. J. Parasitology : 198-204.

Shields, J.D., & C.H. Earley. 1993. Cancrion australiensis new species (Isopoda: Entoniscidae) found in Thalamita sima (Brachyura: Portunidae) from Australia. Int. J. Parasitol. 23: 601-608.

Shiino,, S.M. 1942. On the parasitic isopods of the family Entoniscidae, especially those found in the vicinity of Seto. Memoirs of the College of Science, Kyoto Imperial University, Series B, 17(1): 37-76.

Shiino, S.M. 1954. A new fresh-water entoniscid isopod, Entionella okayamaensis, n. sp. Rep. Fac. Fisheries, Prefectural Univ. Mie 1: 239-246.


Dajid isopods are ectoparasites of euphausiids, mysids, and shrimp. The isopods typically attach to the carapace of their hosts near the juncture of the cephalothorax and abdomen, but some may be found on the host gills or attached to the head of their hosts.

This list is organized alphabetically by genus with type species in bold print.

Each entry is given as: Genus species Authority, year ---hosts

Click here for a reference list of the Authorities and additional citations for the Dajidae

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Authorities and citation list for the Dajidae

Barnard, K.H. 1913. Contributions to the crustacean fauna of South Africa. Ann. S. Afr. Museum 10: 197-240.

Bonnier, J. 1887. Catalogue des Crustacés Malacostracés recueilles dans la baie de Concarneau. Bulletin Scientifique de la France et de Belgique 18: 199-262, 296-356, 361-422.

Bonnier, J. 1903. Sur deux types nouveaux d'Epicarides parasites d'un Cumace et d'un Schizopode. Comptes Rendus Hebdomaires Seances des Academie des Science 136: 102-103.

Brandt, A. 1993. Redescription of Notophryxus clypeatus Sars, 1885, a parasitic isopod of mysidaceans from the Kobleinsey Ridge, North of Iceland. Sarsia 78-123-127.

Buchholz, R. 1874. Die zweite deutsche Nordpolarfahrt im Jahre 1869 und 1870 unter Fuhrung des Kapitan Koldewey. Crustaceen. Leipzig.

Butler, T.H. 1964. Redescription of the parasitic isopod Holophryxus alaskensis Richardson, and a note on its synonymy. J. Fish. Res. Bd. Canada 21(5): 971-976.

Caullery, M. 1897. Branchyophryxus nyctiphanae, n.g. et sp., épicaride nouveau de la famille des Dajidae. Zoologischer Anzeiger 20: 88-92.

Giard, A. & Bonnier, J. 1889. Sur les épicarides de la famille des Dajidae. Bull. Scient. France et Belgique 20: 252-372.

Gilson, G. 1909. Prodajus ostendensis n. sp. étude monographique d'un épicaride parasite du Gastrosaccus spinifer Goes. Bulletin Scientifique de la France et de la Belgique 43: 19-92.

G¢mez, J.G., & Shields, J.D. (in review). Oculoprhyxus bicaulis a new genus and species of dajid isopod parasitic on the euphausiid Stylocheiron spp. G. O. Sars.

Gotto, R.V. 1983. A hitherto undescribed juvenile stage of a female dajid isopod. Journal of Crustacean Biology 3: 629-635.

Holthuis, L.B. 1949. Zonophryxus dodecapus nov. spec., a remarkable species of the family Dajidae (Crustacea: Isopoda) from the Canary Islands. Proc. Koninklijke Nedelandse Akademie van Wetenschappen 52: 208-213.

Kensley, B. 1979. Redescription of Zonophryxus trilobus Richardson, with notes on the male and developmental stages (Crustacea: Isopoda: Dajidae) Proc. Biol. Soc. Wash. 92(3): 665-670.

Koehler, R. 1911. Isopodes nouveaux de la famille des Dajidés provenant des campagnes de la <<Princesse-Alice>>. Bulletin de l'Institut Océanographique 196: 1-34.

Kröyer, H. 1842. Monografisk Fremstilling af Slaegten Hippolytes nordiske Arter. Kongelige Dankse Videnskabenes Selskabs naturviden-skabelige og mathematiske Afhandlinger, Kjobenhavn IX p. 262-263.

Kröyer, H. 1949. Poissons, Crustacés, Mollusques, etc. In P. Gaimard, Voyage de la commission scientifique du Nord, en Scandinavie, en Laponie, au Spiztberg, etc. sur la Corvette <La Recherche> pendant les an nées 1833-1840. Paris, 1849.]

Lo Bianco, S. 1902. Le pesche pelagiche abissale eseguite dal Maia nelle vicinanze de Capri. Mitteilungen Zoologisches Statione Neapel 15: 413-482 (1901).

Nierstrasz, H.F. & Brender á Brandis, G.A. 1923. Die Isopoden der Siboga Expedition. II. Isopoda Genuina I. Epicaridea. Siboga Expeditie 32b: 57-121.

Nierstrasz, H.F. & Brender á Brandis, G.A. 1931. Papers from Dr. Th. Mortensen's Pacific Expedition 1914-1916. Epicaridea II. Videnskabelige Meddelelser fra Dansk Naturhistorisk Forening i Kjobenhavn 91 : 147-225

Packard, A.S. 1867. Observations on the glacial phenomena of the coast of Labrador and Maine with a view of the recent fauna of Labrador. Mem. Bost. Soc. Nat. Hist. 6.

Pillai, N.K. 1963. Isopod parasites of Indian mysids. Annals and Magazine of Natural History Series 13 6:739-743.

Richardson, H. 1904. Contribution to the natural history of the Isopoda. Proceding of the United States National Museum 27: 1-89.

Richardson, H. 1905. (1904). Isopods from the Alaskan salmon investigation. Bulletin of the United States Bureau of Fisheries 24: 204-221.

Richardson, H. 1908. Description of a new isopod genus of the family Dajidae. Proceedings of the United States National Museum 34: 391-392.

Richardson, H. 1908. On some isopods of the family Dajidae from the northwest Pacific Ocean, with descriptions of a new genus and two new species. Proceedings of the United States National Museum 33 (#1586): 689-696.

Richardson, H. 1909. Isopods collected in the northwest Pacific by the U.S. Bureau of Fisheries steamer Albatross in 1906. Proceedings of the United States National Museum 37: 75-129.

Richardson, H. 1910. Marine isopods collected in the Philippines by the U.S. Fisheries Steamer Albatross in 1907-8. Bureau of Fishies Document 736: 1-44.

Richardson, H. 1914. Isopoda. Reports on the scientific results of the Expedition to the Tropical Pacific. Bull. Mus. comp. Zool., Harvard 58: 361-372.

Rustad, D. 1935. Notes on Holophryxus richardi Koehler (?) (Fam. Dajidae). Bergens Museum Arbok 1934, Naturvidanskapelig Rekke 13: 1-31.

Sars, G. O. 1883. Oversigt af Norges Crustaceer med forelöbige Bemaerkninger over de nye eller mindre bekjendte Arter I. Christiania Videnskabelige Forhandlinger 18: 1-124.

Sars, G.O. 1885. Crustacea den Norske Nordhavs Expedition, 1876-78. Norwegian N. Atl. Exped. Zool. 1: 1-276

Sars, G.O. 1885. Notes on some parasites obtained from the Challenger specimens of Schizopoda. Challenger Rep. Zool. 13: 219-221.

Sars, G.O. 1898. An account of the Crustacea of Norway. Vol II. Isopoda. Part XI, XII Oniscidae, Bopyridae, Dajidae. Bergen Museum, Norway. (pp. 221-231).

Schultz, G. A. 1977. Bathypelagic isopod Crustacea from the Antarctic ans Southern Seas. In: Biology of the Antarctic seas V (edited by Pawson D. L.), pp. 69-128.Antarctic Research Series 23, AGU, Washington, D.C.

Schultz, G. A. 1978. More planktonic isopod crustaceans from subantarctic and Antarctic seas. In: Biology of the Antarctic seas VII (Edited by Pawson, D. L.), pp. 77-89. Antarctic Research Series 27, AGU, Washington, D. C.

Schultz, G. A. & Allen, D.M. 1982. Prodajus bigelowensis, new species (Isopoda: Epicaridea: Dajidae) parasite of Mysidopsis bigelowi (Mysidacea) from coastal New Jersey, with observations on infestation. J. Crustacean Biolo gy 2: 296-302.

Sebastian, M. J. 1970. On two isopod parasites of Indian euphausiids. Journal of Natural History 4: 153-158.

Shiino, S.M. 1937. Holophryxus fusiformis, a new species of Dajidae, Epicaridea. Annotationes. Zool. Japonicus 16(3) 188-191.

Shiino, S.M. 1943. On Prodajus bilobatus a new species of the family Dajidae (Epicaridea, Isopoda). J. Sigenkagaku Kenkyusyo 1: 115-118.

Stephensen, K. 1912. Report on the Malacostraca collected by the <<Tjalfe>> expedition, under the direction of Cand. Mag. Ad. S. Jensen, especially at W. Greenland. Videnskabelige Meddelelser fra Dansk Naturhistorisk For ening i Kjobenhavn 64: 57-134.

Vanhoeffen, E. 1914. Die Isopoden der Deutschen Südpolar-Expedition 1901-1903. Deut. Sudpolar Exped. 20 (Zool.) 7:449-598.

Wasmer, R.A. 1988. The parasitic isopod Holophryxus acanthephyrae Stephensen (Epicaridea: Dajidae) from the subantarctic south Pacific, with notes on its synonymy and host. Proc. Biol. Soc. Wash. 101: 20-30.

Acknowledgements and Disclaimers

This list was constructed by Dr. Jeffrey Shields, Virginia Institute of Marine Science, The College of William and Mary. Thanks go to Jaime Gomez at CICIMAR in La Paz, Mexico for his assistance with the list.

Please keep in mind that this is still under construction and some small errors may reside herein. Corrections, additions, and some in-line images are in the "works." Under no circumstances should this list be cited as a scientific publication. The authorities and other references should be consulted for any taxonomic citations.

If you have any questions please contact


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