Brine shrimp (Artemia) are a type of aquatic crustacean. They are found worldwide in saltwater, though not in oceans. Artemia is a well known genus as one variety, the Artemia nyos, a hybrid of Artemia salina, are 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.
Un-hatched brine shrimp 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). Once placed in water, the cyst-like eggs hatch within a few hours, and will grow to a mature length of around one centimeter on average. Brine shrimp have a biological 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. Also, because they have no brain and a very crude nervous/spinal system, they can be used for many experiments without having to worry about animal ethics.
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 (but low in calcium). 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 larvae, of brine shrimp are less than 500 micrometers when they first hatch. They eat micro-algae, but will also eat yeast, wheat flour, soybean powder, or egg yolk.
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 .
- The Taxonomicon & Systema Naturae 2000: Genus Artemia Listings of taxonomy and scientific classification.
- Invertebrate Anatomy OnLine: Artemia franciscana
- Westminster College student research: Science at the Great Salt Lake
- Captain's Artemia pages