Artemia salina

Artemia salina has three eyes and 11 pairs of legs and can grow to about in size. Its blood contains the pigment hemoglobin, which is also found in vertebrates. Males differ from females by having their second antennae markedly enlarged, and modified into clasping organs used in mating. ==Life cycle==

(egg) (larva) Males have two reproductive organs. Prior to copulation, the male clasps the female with his clasping organ, assuming a dorsal position. The claspers hold the female just anterior to the ovisac. A male and female may swim clasped together for a number of days. In this state, the movements of the swimming appendages of the pair beat in a co-ordinated fashion. ==Ecology==

In nature, they live in salt lakes. They are almost never found in an open sea, most likely because of the lack of food and relative defenselessness. However, Artemia species have been observed in Elkhorn Slough, California, which is connected to the sea. However, North American populations are another species, A. franciscana. which is nearly a saturated solution, and can live for several days in solutions very different from sea water, such as potassium permanganate or silver nitrate,. It feeds mainly on green algae. In the UK, the species formerly lived in a number of salt works based around the Solent. ==Uses==

The resilience of these creatures makes them ideal test samples in experiments. Artemia is one of the standard organisms for testing the toxicity of chemicals including screening for insecticidal activity being used by Blizzard et al. 1989 to screen hundreds of semisynthetic avermectins, and by Conder et al. 1992 for the Streptomyces fumanus metabolite dioxapyrrolomycin. In addition, the eggs survive for years. Their durability makes it possible to buy "Artemia growing kits" for children, containing eggs, salt, food, and most necessary tools, as well as plain packets of eggs. These have been most popularly marketed under the name Sea-Monkeys and Aqua Dragons. Shops catering for aquarists also sell frozen Artemia as fish food, and occasionally packets of eggs for aquarists to grow them as live fish food. Artemia occurs in vast numbers in the Great Salt Lake where it is commercially important. ==Taxonomy, distribution and conservation==

Artemia salina was first described (as Cancer salinus) by Carl Linnaeus in his '' in 1758. This was based on a report by a German named Schlosser, who had found Artemia'' at Lymington, England. That population is now extirpated, although specimens collected there are retained in zoological museums. As presently defined, Artemia salina is restricted to the Mediterranean region of Southern Europe, Anatolia and Northern Africa. An alternative taxonomic treatment is to recognize the extirpated English population as a species of its own, to which the name Artemia salina should be restricted. In that case the species native to the Mediterranean region of Southern Europe, Anatolia and Northern Africa can be referred to as Artemia tunisiana, but at present most authorities reject this treatment and consider Artemia tunisiana as a synonym of Artemia salina. Some have considered the North African population distinct and proposed that the name Artemia tunisiana should be restricted to that group, but this is contradicted by genetic evidence showing that South European and North African populations belong to the same species. ==References==