for2: Sea-Monkey

Brine shrimp are a species of aquatic crustaceans of the genus Artemia. Artemia, the only genus in the family Artemiidae, have evolved little since the Triassic period. First discovered in Lymington, England, in 1755, 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.

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). Once placed in 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 other characteristics such as their ability to remain dormant for long periods, has made them invaluable in scientific research, including space experiments.

Diet

Brine shrimp eat micro-algae, but will also eat yeast, wheat flour, soybean powder, or egg yolk.

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 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 with reasonable temperatures. This makes sense as these areas are uninhabitable for potential predators.

'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.