brine shrimp

(click to enlarge)
Brine shrimp (Artemia salina) (credit: Douglas P. Wilson)

Any of several small crustaceans (genus Artemia) inhabiting brine pools and other highly salty inland waters throughout the world. A. salina, which occurs in vast numbers in Great Salt Lake, Utah, is commercially important. Young brine shrimp hatched there from dried eggs are used widely as food for fish and other small animals in aquariums. Up to 0.6 in. (15 mm) long, the brine shrimp's body has a distinguishable head and a slender abdomen. It normally swims upside down, and it feeds primarily on green algae, which it filters from the water with its legs.

For more information on brine shrimp, visit Britannica.com.

Artemia salina

FAMILY

Artemiidae

TAXONOMY

Artemia salina Linnaeus, 1758, England; and a cluster of about 10 related species.

OTHER COMMON NAMES

French: Crevette primitive, singe de mer; German: Salzwasser Feenkrebs, Salzkrebs, Urzeitkrebs.

PHYSICAL CHARACTERISTICS

Brine shrimp refers to Artemia salina and about 10 other related species. They are rather small anostracans, reaching only 0.6 in (15 mm) in length. The color varies from almost hyaline and transparent to bright red. The male antenna is strongly modified, but is not sufficient to identify the species. Microcharacters are required for identification, as well as biochemical and molecular methods.

DISTRIBUTION

The original specimens of A. salina were sampled from salt works at Lymington, England, but that population has long been extinct. The genus is widespread in bodies of salt water on all continents, and was introduced to Australia in the twentieth century. (Specific distribution map not available.)

HABITAT

Natural or artificial salt lakes and salinas (saltwater marshes) worldwide.

BEHAVIOR

The behavior of this species is similar to that of Sudanese fairy shrimp.

FEEDING ECOLOGY AND DIET

Artemia is a small-particle filter feeder. It can be grown on algae, yeasts, and a wide variety of micronized inert particles.

REPRODUCTIVE BIOLOGY

Like all fairy shrimps, artemia develops rapidly. The time between the hatching of the nauplius larva and maturation is slightly longer than a week. Artemia is also noted for its reproductive flexibility: under favorable conditions, it produces clutches of eggs at close intervals. Some species and/or strains may reproduce parthenogenetically, while others are viviparous. Artemia is the only known genus of fairy shrimp that shows this degree of versatility in reproductive tactics.

CONSERVATION STATUS

Not listed by the IUCN. The typical locality of the true brine shrimp has long disappeared; consequently, there is some uncertainty as to what constitutes the true habitat of Artemia salina, although it is likely geographically widespread. Artemia monica (Verrill, 1869) is one member of restricted occurrence. This member of the genus is limited to Mono Lake in California, where measures have been taken to prevent wide fluctuations in the salinity of the lake.

SIGNIFICANCE TO HUMANS

It has long been known that the presence of Artemia spp. (and of Parartemia as well) improves salt production in brine pools. That principle is still widely applied in salt works. In addition, an industry of Artemia cyst harvesting has developed around large salt lakes (Great Salt Lake in Utah, Kara Bogaz Gol in the Caspian basin, and others), where these cysts float in large masses on the surface of the water. The cysts can be collected in nets or scooped up from the lake shores where they accumulate. These cysts are later hatched to feed fish larvae, either in industrial aquaculture or by aquarium hobbyists. There are also a few instances of direct human consumption of brine shrimp, the best-known example being that of the Dawada (worm eaters) tribes in the Fezzan desert of Libya.

For non-zoological information on this animal as a pet, see Sea-Monkey.

Brine shrimp
Artemia salina
Scientific classification
Kingdom:	Animalia
Phylum:	Arthropoda
Subphylum:	Crustacea
Class:	Branchiopoda
Order:	Anostraca
Family:	Artemiidae Grochowski, 1895
Genus:	Artemia Leach, 1819
Species
Artemia franciscana Artemia gracilis Artemia monica Artemia parartemia Artemia parthenogenetica Artemia persimilis Artemia pollicaris Artemia salina Artemia salina x nyos Artemia sinica Artemia tibetiana Artemia tunisiana Artemia urmiana

Brine shrimp is the English name of the genus Artemia of aquatic crustaceans. Artemia, the only genus in the family Artemiidae, have evolved little since the Triassic period. First discovered in Lymington, England, in 1755,^[1] Artemia are found worldwide in inland saltwater lakes, but not in oceans.

Artemia is a well known genus as one variety (sometimes identified as a new species Artemia salina x nyos), a cultivated subspecies of Artemia salina, is sold as a novelty gift, most often under the marketing name Sea-Monkeys.

Contents 1 Life cycle 2 Diet 3 Tolerance to salinity 4 Nutritional benefits 5 Threatened 6 References 7 Bibliography 8 External links

Life cycle

Brine shrimp eggs are metabolically inactive and can remain in total stasis for several years while in dry oxygen-free conditions, even at temperatures below freezing. This characteristic is called cryptobiosis meaning "hidden life" (also called diapause). While in cryptobiosis, brine shrimp eggs can survive temperatures of liquid air (-190 C/ -310 F) and a small percentage can survive above boiling temperature (105 C/ 221 F) for up to two hours.^[2]

Once placed in brine (salt)water, the cyst-like eggs hatch within a few hours. The nauplii, or larvae, are less than 0.5mm in length when they first hatch. Brine shrimp have a biological life cycle of one year, during which they grow to a mature length of around one cm on average. This short life span, along with other characteristics such as their ability to remain dormant for long periods, has made them invaluable in scientific research, including space experiments.

Diet

Wild brine shrimp eat microscopic planktonic algae. Cultured brine shrimp can also be fed particulate foods including yeast, wheat flour, soybean powder, or egg yolk.^[3]

Tolerance to salinity

Brine shrimp can tolerate varying levels of salinity. A common biology experiment in school is to investigate the effect of salinity levels on the growth of these creatures.

Nutritional benefits

The nutritional properties of newly hatched brine shrimp make them particularly suitable to be sold as aquarium and human food as they are high in lipids and unsaturated fatty acids (but low in calcium).

Threatened

Artemia monica, the variety commonly known as Mono Lake brine shrimp, are found only in Mono Lake, Mono County, California. In 1987, Dr. Dennis D. Murphy from Stanford University petitioned the United States Fish and Wildlife Service to add Artemia monica to the endangered species list under the Endangered Species Act 1973. Despite there being trillions of these creatures in Mono Lake, it was felt that rising levels of salinity and sodium hydroxide concentration of the lake would endanger them because of the increase in pH. However, the US Fish and Wildlife Service reported in the Federal Register on 7 September 1995 that this brine shrimp did not warrant listing after the threat to the lake was removed following a revised policy by the California State Water Resources Control Board.^[4]

References

1. ^ Eads, Brian D. (2004). "SALTY SURVIVORS: Artemia: Basic and Applied Biology". J Exp Biol 207 (11): 1757–8. doi:10.1242/jeb.01005. http://jeb.biologists.org/cgi/content/full/207/11/1757. Retrieved 2008-03-20. 
2. ^ http://www.drwhitey.com/Ecology/Artemia/BrineShrimp.html
3. ^ Schumann, Kai (1997-08-10). "Artemia (Brine Shrimp) FAQ 1.1". Portland State University. Archived from the original on 2007-08-14. http://web.archive.org/web/20070814003850/http://web.cecs.pdx.edu/~davidr/discus/articles/artemia.html. Retrieved 2008-03-20. 
4. ^ United States Fish and Wildlife Service (1995). "Endangered and Threatened Wildlife and Plants; 12-Month Finding for a Petition to List the Mono Lake Brine Shrimp as Endangered". Federal Register 60 (173): 46571–46572. http://frwebgate3.access.gpo.gov/cgi-bin/waisgate.cgi?WAISdocID=9913285177+1+0+0&WAISaction=retrieve. 

Bibliography

• Salty Survivors: Artemia: Basic and Applied Biology, Edited by Th. J. Abatzopoulos, J. A. Beardmore, J. S. Clegg and P. Sorgeloos , Kluwer Academic Publishers (2002). ISBN 1402007469

External links

• http://sn2000.taxonomy.nl/Taxonomicon/TaxonTree.aspx?id=33062 "Genus Artemia", The Taxonomicon & Systema Naturae 2000
• http://web.archive.org/web/20060423082302/http://www.lander.edu/rsfox/310artemiaLab.html "Artemia franciscana" Invertebrate Anatomy Online
• http://ut.water.usgs.gov/shrimp/index.html "Brine Shrimp and Ecology of Great Salt Lake", United States Geological Survey

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