Mono Lake Brine Shrimp
October 2, 2012 by staff
Mono Lake Brine Shrimp, Artemia is a genus of aquatic crustaceans known as brine shrimp. Artemia, the only genus in the family Artemiidae, has changed little externally since the Triassic period. The historical record of the existence of Artemia dates back to 982 from Urmia Lake, Iran, although the first unambiguous record are the report and drawings made by Schl?sser in 1756 of animals from Lymington, England. Artemia populations are found worldwide in inland saltwter lakes, but not in oceans. Artemia are able to avoid cohabitating with most types of predators, such as fish, by their ability to live in waters of very high salinity up to 250.
The ability of the Artemia to produce dormant eggs, known as cysts, has led to extensive use of Artemia in aquaculture. The cysts may be stored for long periods and hatched on demand to provide a convenient form of live feed for larval fish and crustaceans. Nauplii of the brine shrimp Artemia constitute the most widely used food item, and over 2000 tonnes of dry Artemia cysts are marketed worldwide annually. In addition, the resilience of Artemia makes them ideal animals for running biological toxicity assays and is now one of the standard organisms for testing the toxicity of chemicals. A breed of Artemia is sold as a novelty gift under the marketing name Sea-Monkeys.
The brine shrimp Artemia comprises a group of eight species very likely to have diverged from an ancestral form living in the Mediterranean area about 5.5 million years ago.
Artemia is a typical primitive arthropod with a segmented body to which is attached broad leaf-like appendages. The body usually consists of 19 segments, the first 11 of which have pairs of appendages, the next two which are often fused together carry the reproductive organs, and the last segments lead to the tail. The total length is usually about 8-10 millimetres (0.31-0.39 in) for the adult male and 10-12 mm (0.39-0.47 in) for the female, but the width of both sexes, including the legs, is about 4 mm (0.16 in).
The body of Artemia is divided into head, thorax, and abdomen. The entire body is covered with a thin, flexible exoskeleton of chitin to which muscles are attached internally and shed periodically. In female Artemia a moult precedes every ovulation.
For brine shrimp, many functions, including swimming, digestion and reproduction are not controlled through the brain; instead, local nervous system ganglia may control some regulation or synchronization of these functions. Artemia have two types of eyes. They have two widely separated compound eyes mounted on flexible stalks. These compound eyes are the main optical sense organ in adult brine shrimps. The median eye, or the naupliar eye, is situated anteriorly in the centre of the head and is the only functional optical sense organ in the nauplii, which is functional until the adult stage.
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