OSTRACOD RESEARCH

at the Lake Biwa Museum, Japan


Robin James Smith

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Introduction
Carapace
Appendages
Habitats
Diet
Predators
Amazing Facts

Ostracods' diet

The freshwater ostracod Heterocypris incongruens grazing algae on a fallen leaf.
Most free-living ostracods are considered to feed on algae and organic detritus, but some ostracods are omnivores, predators and scavengers. Additionally, some ostracods have commensal relationships with (mostly) other larger crustaceans, such as crayfish, while a small number of ostracods are parasites on sharks, sea urchins, polychaete worms and amphipods.

Whether ostracods are prey or predator of certain groups can be related to population densities. In experiments with fish fry and ostracods, it was noted that the fish eat the ostracods, but if the number of ostracods is large, the tables are tuned; the ostracods attack and eat the fish fry, leaving just the vertebrae and scales (Liperovskaya 1948).

In the marine genus Rutiderma males and females have different feeding strategies; females are predators, while males, with more poorly developed maxillae, are probably detritus feeders (Kornicker 1985).

FoodNotes References
Organic detritus Organic detritus (i.e. the remains of dead organisms and faecal material) is an important food source for many species.Cannon 1933; Kornicker 1975; Fryer 1997; Strayer 1985; Modig et al. 2000; Smith & Delorme 2010
AlgaeA wide variety of algae is eaten by ostracods, including diatoms, single-celled algae, colonial algae and filamentous algae. In a study, a large quantity of algae was found in the guts of nine freshwater ostracod species. Marine myodocopids also consume algae (e.g. diatoms) as well as other things.Liperovskaya 1948; Kornicker 1975; Arashkevich 1977; Strayer 1985; Fryer 1997
BacteriaBacteria is a food source for ostracods, including sulfur-oxidizing bacteria in a cave system.Liperovskaya 1948; Peterson et al. 2013
Cyanobacteria (blue-green algae)Blue-green algae have been found in ostracod guts, and ostracods have been reported feeding on microbial mats of blue-green algae in hot springs.Liperovskaya 1948; Wickstrom & Castenholz 1985
FungiThe hyphae of fungi have been found in the guts of the freshwater ostracod Heterocypris incongruens.Liperovskaya 1948
ProtozoansProtozoans, including radiolarians, feature in the diets of ostracods.Liperovskaya 1948; Arashkevich 1977
Plants and pollenPlant material, rotten wood and pollen have been found in the guts of ostracods. They also eat fallen leaves.Liperovskaya 1948; Campbell 1995; Fryer 1997
Rotifers (Rotifera)Experimental evidence indicates that ostracods ingest rotifers.Liperovskaya 1948
Oligochaetes (Annelida, Oligochaeta)Ostracods can tackle oligochaetes much larger than themselves by attacking in packs.Liperovskaya 1948
Polychaete worms (Annelida, Polychaeta)The spines and bristles of polychaete worms have been found in the guts of some myodocopid ostracods, and observations of myodocopids attacking live polychaete worms have been reported.Kornicker 1975; Vannier et al. 1998
Round worms (Nematoda)Nematodes have been recovered from the guts of ostracods.Kornicker 1967; Kornicker 1969; Kornicker 1975
Arrow worms (Chaetognatha)The remains of arrow worms have been found in ostracod stomachs.Cannon 1940
Copepods (Crustacea, Copepoda)Copepods are eaten by both marine and freshwater ostracods.Cannon 1933; Kornicker 1967; Kornicker 1969; Kornicker 1975; Kornicker et al. 1976; Arashkevich 1977; De Deckker 1983
Other ostracods (Crustacea, Ostracoda)Studies have shown that a small part of the diet of the marine giant ostracod Gigantocypris muelleri is made up of other ostracods, and marine planktonic halocyprid ostracods are consumed by Macrocypridina castanea. In non-marine habitats, Australocypris insularis was reported to feed on other smaller ostracod species, while Heterocypris incongruens is known to be cannibalistic. Kornicker 1969; Kornicker et al. 1976; Moguilevsky & Gooday 1977; Campbell 1995; Rossi et al. 2011
Mysids (Crustacea, Mysida)The remains of a mysid have been reported from the stomach of Macrocypridina castanea.Cannon 1933
Krill (Crustacea, Euphausiacea)Parts of krill appendages have been found in the stomachs of Macrocypridina castanea.Kornicker et al. 1976
Water fleas (Crustacea, Caldocera)As well as consuming dead cladocerans, ostracods also predate on live specimens. Observations revealed that ostracods attack the antennae of Daphnia first, immobilising the victim before killing and eating it.Liperovskaya 1948; Fryer 1997
Non-biting midge larvae (Insecta, Diptera, Chironomidae)Ostracods have been known to eat non-biting midge larvae by attacking in groups.Rossi et al. 2011
Mosquito larvae (Insecta, Diptera, Culicidae)Mosquito larvae can be attacked and eaten by ostracods.Rossi et al. 2011
Snails (Mollusca, Gastropoda) The young of freshwater snails are predated on by ostracods, including snails that are a vector of the disease schistosomiasis. A shell of a heteropod (planktonic gastropod) was recovered from the stomach of a marine ostracod.Müller 1890; Sohn & Kornicker 1972
Amphibian eggs (Amphibia, Anura)Some common species of freshwater ostracods have a taste for both toad and frog eggs.Gray et al. 2011; Ottonello & Romano 2011
Fish (Osteichthyes)Young fish have been found from the guts of the marine giant planktonic ostracod Gigantocypris mulleri, and freshwater fish fry can also be attacked by ostracods. The marine bioluminescent ostracod Vargula tsujii is reported to feed on the mucus and small pieces of skin of live fish, apparently not causing serious damage, but if the fish is attacked by isopods, Vargula tsujii will enter the fish's wounds to feed on the internal organs.Cannon 1940; Liperovskaya 1948; Stepien & Brusca 1985
Dead animalsA variety of dead animals, such as fish, squid, annelid worms etc. are scavenged by some species of ostracods.Vannier et al. 1998

Note that studies of gut contents of ostracods are not able to determine if organisms have been actively predated or scavenged.

Parasitic and commensal ostracods

HostNotes References
Sharks and rays (Chondrichthyes)The myodocopid ostracod Sheina orri is a parasite on the gills of the epaulette shark and the bluespotted ribbontail ray, while Vargula parasitica has been found on the gills and in the nasal tubes of hammerhead sharks.Wilson 1913; Bennett et al. 1997
Fish (Osteichthyes) The marine bioluminescent ostracod Vargula tsujii is a noctunral feeder on the mucus and small pieces of skin of live fish, apparently not causing serious damage. Occasionally, fish will shake off the ostracods or swim away. If the fish is injured, the ostracods may predate the fish (see above table). A handful of Vargula parasitica specimens have been recovered from the gills of two species of fish, the rock hind and the blue runner.Wilson 1913; Stepien & Brusca 1985
Decapods (Crustacea, Decapoda) The Cytheroidea family Entocytheridae is a large groups of about 220 species, most of which are found clinging to crayfish in an apparent commensal relationship. They are also found on a species of freshwater crab.Hart & Hart 1974
Amphipods (Crustacea, Amphipoda) Several species of Paradoxostomatidae ostracods of the genus Acetabulastoma are parasites on amphipods. Some Entocytheridae species are commensal on amphipods.Schornikov 1970; Hart & Hart 1974
Isopods (Crustacea, Isopoda) Groundwater isopods are the hosts of a small number of Entocytheridae species.Hart & Hart 1974
Sea urchins (Echinodermata, Echinoidea) Sea urchins in the Pacific are the hosts of the genus Echinophilus, a parasitic genus of Paradoxostomatidae. A species of the Pontocypridoidea genus Pontocypria is also found in association with echinoids, although the exact relationship remains unclear.Schornikov 1973; Maddocks 1979; Kretzler 1984
Starfish (Echinodermata, Asteroidea)Pontocypria helenae can be found clinging to the tube feet of three species of Antarctic starfish, in a probable commensal relationship.Maddocks 1968
Polychaete worms (Annelida, Polychaeta)Mungava riseri, a marine Candonidae, is found attached to and eating the gills of a polychaete worm.Maddocks 1979
Sponges (Porifera)A study of a marine sponge collected in Madagascar, revealed a commensal species, Pontocypria humesi, living inside. In Lake Titicaca, Chlamydotheca incisa, normally found in temporary habitats, was found associated with a freshwater sponge.Maddocks 1968; Martens & Harrison 1993.
The red swamp crayfish - a home for entocytherid ostracods.

Often the exact relationship between symbiotic ostracods and their hosts i.e. if they are parasitic or commensal, is not clearly known.

The entocytherid ostracods are mostly found on crayfish, and probably feed on detritus on the body of their hosts, but their ecology is poorly understood.

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References

Arashkevich, E. G. 1977. A relationship between the daily feeding rhythm and the vertical migration of Cypridina sinuosa (Ostracoda, Crustacea) in the western part of the equatorial Pacific. Okeanologiya, 17, 707-712.

Bennett, M. B., Heupel, M. R., Bennett, S. M. & Parker, A. R. 1997. Sheina orri (Myodocopa: Cypridinidae), an ostracod parasitic on the gills of the epaulette shark, Hemiscyllium ocellatum (Elasmobranchii: Hemiscyllidae). International Journal of Parasitology, 27, 275-281.

Campbell, C. E. 1995. The influence of a predatory ostracod, Australocypris insularis, on zooplankton abundace and species composition in a saline lake. Hydrobiologia, 302, 229-239.

Cannon, H. G. 1933. On the feeding mechanism of certain marine ostracods. Transactions of the Royal Society of Edinburgh, 57, 739-764.

Cannon, H. G. 1940. On the anatomy of Gigantocypris mulleri. In Discovery Reports, 19, 185-244.

De Deckker, P. 1983. Notes on the ecology and distrubution of non-marine ostracods in Australia. Hydrobiologia, 106, 223-234.

Fryer, G. 1997. The horse-trough ostracod Heterocypris incongruens Naturalist, 122, 121-135.

Gray E. P., Nunziata, S., Snodgrass, J. W., Ownby, D. R. & Havel, J. E. 2010. Predation on Green Frog Eggs (Rana clamitans) by Ostracoda. Copeia 2010, 452-456.

Hart, D. G. & C. W. Hart, Jr.. 1974. The ostracod family Entocytheridae. The Academy of Natural Sciences of Philadelphia, Monograph 18, 1-239.

Kornicker, L. S. 1967. A Study of Three Species of Sarsiella (Ostracoda: Myodocopa). Proceedings of the United States National Museum, 122, 1-45.

Kornicker, L. S. 1969. Morphology, ontogeny, and intraspecific variation of Spinacopia, a new genus of myodocopid ostracod (Sarsiellidae). Smithsonian Contributions to Zoology, 8, 1-50.

Kornicker, L. S. 1975. Antarctic Ostracoda (Myodocopina). Part 1. Smithsonian Contributions to Zoology, 163, 1-374.

Kornicker, L. S., Wirsing, S. & McManus, M. 1976. Biological Studies of the Bermuda Ocean Acre: Planktonic Ostracoda. Smithsonian Contributions to Zoology, 223, 1-34.

Kretzler, J. E. 1984. Echinophilus xiphidion, new species (Ostracoda, Paradoxostomatidae) parasitic on regular echinoids of the northeastern Pacific. Journal of Crustacean Biology, 4, 333-340.

Liperovskaya, E. S. 1948. On the feeding of freshwater ostracods. Zoologichesky Zhurnal, 27, 125-136. [In Russian, with English translation available at Aquatic Commons.]

Maddocks, R. F. 1968. Commensal and free-living species of Pontocypria Müller, 1894 (Ostracoda, Pontocyprididae) from the Indian and Southern Oceans. Crustaceana, 15, 121-136.

Maddocks, R. F. 1979. Two new examples of symbiosis or parasitism in cypridacean Ostracoda. Crustaceana, 37, 1-12.

Martens, K. & Harrison, K. 1993. An interesting association between a freshwater sponge (Porifera) and an ostracod (Crustacea) in Lake Titicaca (Bolivia). Verhandlungen des Internationalen Verein Limnologie, 25, 923-924.

Modig, H., van de Bund, W. J. & Ólafsson, E. 2000. Uptake of phytodetritus by three ostracod species from the Baltic Sea: effects of amphipod disturbance and ostracod density. Marine Ecology Progress Series, 202, 125-134.

Moguilevsky, A. & Gooday, A. J. 1977. Some observations on the vertical distribution and stomach contents of Gigantocypris muelleri Skogsberg 1920 (Ostracoda, Myodocopina). In: Loffler, H. & Danielopol, D. (eds) Aspects of ecology and zoogeography of recent and fossil Ostracoda. Junk, The Hague, 263-270.

Müller, G. W. 1890. Neue Cypridiniden. Zoologische Jahrbuecher, 5, 211-252.

Ottonello, D. & Romano, A. 2011. Ostracoda and Amphibia in temporary ponds: who is the prey? Unexpected trophic relation in a mediterranean freshwater habitat. Aquatic Ecology, 45, 55-62.

Peterson, D. E., Finger, K. L., Iepure, S., Mariani, S., Montanari, A. & Namiotko, T. 2013. Ostracod assemblages in the Frasassi Caves and adjacent sulfidic spring and Sentino River in the northeastern Apennines of Italy. Journal of Cave and Karst Studies, 75, 11-27.

Rossi, V., Benassi, G., Belletti, F. & Menozzi, P. 2011. Colonization, population dynamics, predatory behaviour and cannibalism in Heterocypris incongruens (Crustacea: Ostracoda). Journal of Limnology, 70, 102-108.

Schornikov, E. I. 1970. Acetabulastoma, a new genus of ostracods - parasites of Amphipoda. Zoologichesky Zhurnal, 49, 1132-1143. [In Russian]

Schornikov, E. I. 1973. Ostracods (Crustacea, Ostracoda), ectoparasites of sea urchins. Parazitologiya 7, 135-144. [In Russian].

Smith, A.J., & Delorme, L.D. 2010. Ostracoda. In: Thorp, J.H., Covich, A.P. (Eds.), Ecology and Classification of North American Freshwater Invertebrates, third ed. Elsevier Publishing, London, pp. 725-771.

Sohn, I. G. & Kornicker, L. S. 1972. Predation of schistosomiasis vector snails by Ostracoda (Crustacea). Science, 175, 1258-1259.

Stepien, C. A. & Brusca, R. C. 1985. Nocturnal attacks on nearshore fishes in southern California by crustacean zooplankton. Maine Ecology - Progress Series, 25, 91-105.

Strayer, D. 1985. The benthic micrometazoans of Mirror Lake, New Hampshire. Arch. Hydrobiologia Suppl. 72, 287-426.

Vannier, J., Abe, K. & Ikuta, K. 1998. Feeding in myodocopid ostracods: functional morphology and laboratory observations from videos. Marine Biology, 132, 391-408.

Wickstrom, C. E. & Castenholz, R. W. 1985. Dynamics of cyanobacterial and ostracod interactions in an Oregon hot spring. Ecology, 66, 1024-1041.

Wilson, C.B. 1913. Crustacean parasites of West Indian fishes and land crabs, with descriptions of new genera and species. Proceedings of the United States National Museum, 44, 189-277.

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