Brine shrimp
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| Brine Shrimp | ||||||||||||||
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 Artemia salina | ||||||||||||||
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Artemia franciscana |
Brine shrimp (Artemia) are a primitive type of aquatic crustacean. They are more closely related to zooplankton than to true shrimp and are found worldwide in saltwater, though not in oceans. Artemia is a well known genus as one variety, the Artemia salina, has been sold as novelty gifts, most commonly under the marketing name Sea-Monkeys.
Artemia were first discovered in Lymington, England in 1755. There are mixed views on whether all brine shrimp are part of one species or whether the varieties that have been identified are properly classified as separate species.
Brine shrimp are metabolically inactive as embryos and can remain in this state for several years in dry oxygen-free conditions. Once placed in water, the cyst-like embryos hatch within a few hours, and will grow to a length of around one centimeter on average. Brine shrimp have a life cycle of one year. This short life span, and other characteristics, such as their ability to remain dormant for long periods, have made them invaluable in scientific research, including space experiments.
Brine shrimp can tolerate varying levels of salinity, and a common biology experiment in school is to investigate the effect of salinity levels on the growth of these creatures.
The nutritional properties of newly hatched brine shrimp make them particularly suitable to be sold as aquarium food as they are high in lipids and unsaturated fatty acids. These nutritional benefits are likely to be one reason that brine shrimp are found only in highly salinated waters, as these areas are uninhabitable for potential predators.
The nauplii, or larva, of brine shrimp are less than 500 micrometers when they first emerge. They eat micro-algae, but will also eat yeast, wheat flour, soybean powder, or egg yolk.
Artemia monica
Artemia monica, the variety commonly 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 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 [1] (http://endangered.fws.gov/federalregister/1995/n950907b.pdf) [PDF].
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