Artemia salina is the scientific name for Sea Monkeys. These popular, odd looking creatures are advertised as an easy to care for pet that grows quickly and does not have a very long life span.
Brine shrimp are not closely related to the shrimp we eat. One interesting point in their evolution is that their ancestors are fresh-water specimens including the fairy shrimp, which do not adapt well to any change in ions or temperature of the water.
Artemia salina may have become a general name for the many different species.
There is no threat for the brine shrimp, because it reproduces quickly. It is easy to find, and the cost to catch and culture them is low.
US Federal List: no special status
CITES: no special status
The brine shrimp does not adversely affect humans, because it is not bothersome or poisonous.
Brine shrimp are useful in toxicity tests and for education purposes because they reproduce quickly and their environment is easy to replicate. They are used to teach students the proper technique to observe live specimens and how to design experiments to determine behavior, means of obtaining food, and most optimal environment for reproduction and development.
Both the eggs and adults are used as feed for coral, larval fish and other crustacea, because of their low cost and ease of use. They cost about $7 per pound and their prime selling time is May to July, but they can be produced at any time of year in a laboratory.
Positive Impacts: pet trade ; research and education
Artemia salina live on photosynthetic green algae, one type is Dunaliella. They obtain food by either filtering small particles with fine slender spines on the legs as they swim or by grazing on bottom mud and scraping algae off rocks with quick movements of their appendages. After the algae is captured, a feeding current moves it anteriorly to the mouth via a central median food groove, utilizing the regular rhythm of the phyllopodia, or leaf-like appendages.
Plant Foods: algae; phytoplankton
Foraging Behavior: filter-feeding
Primary Diet: planktivore
The brine shrimp is found in inland salt water bodies such as the Great Salt Lake in northern Utah, on the rocky coast south of San Francisco, and in the Caspian Sea. They also occur in many other bodies of water with any salt content, including the intermountain desert region of the western United States, salt swamps near any coast, and many man-made saltpans around the world.
Biogeographic Regions: nearctic (Native ); palearctic (Native )
Artemia salina have a remarkable resistance to change and are able to live in a wide variety of water salinity. All contain some salt content ranging from seawater (2.9-3.5%) to the Great Salt Lake (25-35%), and they can tolerate up to a 50% salt concentration, which is almost saturated. Some are found in salt swamps just inland of the dunes at the seashore, but never in the ocean itself, because there are too many predators. They also inhabit man-made evaporation ponds, used to obtain salt from the ocean. Their gills help them to deal with the high salt content by absorbing and excreting ions as necessary and producing a concentrated urine from the maxillary glands. The temperature of the water also varies greatly from around six to 37 deg C, with the optimal reproduction temperature at about 25 deg C or room temperature. One advantage of their salty location means that they have very few predators, but the disadvantage is their diet is limited.
Habitat Regions: saltwater or marine
Aquatic Biomes: lakes and ponds; temporary pools; brackish water
An adult Artemia salina is usually about 8-10 mm but can reach up to 15 mm depending on its environment. It has an elongated body divided into at least 20 segments and attached to its trunk are approximately 10 sets of flat, leaf-like appendages called phyllopodia that beat in a regular rhythm. The adults can be pale white, pink, green, or transparent and usually live for a few months. They have compound eyes set on stalks and reduced mouthparts.
Artemia salina is in the order Anostroca, literally meaning "no shell," which classifies the shrimp with other species that have no carapace (a hard, bony outer covering). Its subclass Brachiopoda literally means "gill foot," referring to the fact that the gills are on the outer side of the limb bases.
Range length: 8 to 15 mm.
Average length: 8-10 mm.
Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry
In the Great Salt Lake studies have shown that many males are present and reproduction occurs when a male clasps a female with his large second antennae and fertilizes her eggs, producing diploid zygotes. Then she lays the eggs in a brood sac in the water. Parthenogenesis, or reproduction without fertilization, is also common among A. salina, particularly in Europe. Parthenogenesis is common when males are not present. During parthenogenesis, a female lays unfertilized eggs that will develop into female offspring. These eggs can be either diploid, tetraploid, or octoploid. Artemia salina eggs will only hatch if environmental conditions are right. The temperature must be around 30 deg C, the water supply plentiful, and the salt concentration not too high. If these conditions are not met, fertilized eggs are deposited as cysts and remain dried and surrounded by a thick shell until they are ready to develop, possibly up to 50 years. The cyst may be immersed in water several times before it will hatch and some require sustained hydration for at least 36 hours to ensure that the population is not wiped out when insufficient rain falls. A brine shrimp takes about one week to mature from a nauplii larva to an adult and then lives for several months and can reproduce up to 300 new nauplii every four days.
Key Reproductive Features: parthenogenic ; sexual ; fertilization (Internal ); oviparous
Parental Investment: no parental involvement
Artemia salina is a species of brine shrimp – aquatic crustaceans that are more closely related to Triops and cladocerans than to true shrimp. It belongs to a lineage that does not appear to have changed much in 100 million years.
Artemia salina is native to saline lakes, ponds, and temporary waters (not seas) in the Mediterranean region of Southern Europe, Anatolia, and Northern Africa.[2][3] Considerable taxonomic confusion exists, and some populations elsewhere have formerly been referred to as this species, but are now recognized as separate species.[2]
Artemia salina has three eyes and 11 pairs of legs and can grow to about 15 mm (0.6 in) 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.[4]
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.[4] The females can produce eggs either as a result of mating or via parthenogenesis. There are two types of eggs: thin-shelled eggs that hatch immediately and thick-shelled eggs, which can remain in a dormant state. These cysts can last for a number of years, and hatch when they are placed in saltwater. Thick-shelled eggs are produced when the body of water is drying out, food is scarce, and the salt concentration is rising. If the female dies, the eggs develop further. Eggs hatch into nauplii that are about 0.5 mm in length. They have a single simple eye that only senses the presence and direction of light. Nauplii swim towards the light, but adults swim away from it. Later, the two more capable eyes develop, but the initial eye also stays, resulting in three-eyed creatures.[5]
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.[6] However, North American populations are another species, A. franciscana.[2] Unlike most aquatic animals, Artemia swims upside down.[5]
Artemia species can live in water having much more or much less salt content than normal seawater. They tolerate salt amounts as high as 25.0%,[5] 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,[6] while iodide—a frequent addition to edible salt—is harmful to them. The animal's colour depends on the salt concentration, with high concentrations giving them a slightly red appearance. In fresh water, Artemia salina dies after about an hour. It feeds mainly on green algae.[7]
The species formerly lived in a number of salt works based around the Solent.[8] They were observed only in the brine tanks where the concentrated salt water was held before boiling, but were probably also present in the salt pans.[8] At least some of the salt harvesters thought they helped clean the brine and would deliberately introduce them into the tanks. With the decline of the salt works the species became extinct in England.[8]
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[9] including screening for insecticidal activity – being used to by Blizzard et al 1989 to screen hundreds of semisynthetic avermectins, and by Conder et al 1992 for the Streptomyces fumanus metabolite dioxapyrrolomycin.[10] In addition, the eggs survive for years. Hence it is possible to buy eggs and also "Artemia growing kits" for children, containing eggs, salt, food and most necessary tools. These have been most popularly marketed under the name Sea-Monkeys. Shops catering for aquarists also sell frozen Artemia as fish food. Artemia occurs in vast numbers in the Great Salt Lake where it is commercially important.[7] However, nowadays it is believed that the brine shrimp of this lake is another species, A. franciscana.[11]
Artemia salina was first described (as Cancer salinus) by Carl Linnaeus in his Systema Naturae in 1758. This was based on a report by a German called Schlosser, who had found Artemia at Lymington, England.[12] That population is now extirpated, although specimens collected there are retained in zoological museums.[13]
As presently defined, A. salina is restricted to the Mediterranean region of Southern Europe, Anatolia and Northern Africa.[2][3] Some populations elsewhere have formerly been referred to as this species, but are now recognized as separate, including A. franciscana of the Americas.[2] That species has been widely introduced to places outside its native range, including the Mediterranean region, where it locally outcompetes the native A. salina. This has already happened in parts of Portugal, Spain, France, Italy and Morocco.[14][15]
An alternative taxonomic treatment is to recognized the extirpated English population as a species of its own, to which the name A. 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 A. tunisiana,[15][16] but at present most authorities reject this treatment and consider A. tunisiana as a synonym of A. salina.[17] Some have considered the North African population distinct and proposed that the name A. tunisiana should be restricted to it,[18] but this is contradicted by genetic evidence, which shows that South European and North African populations belong to the same species.[15]
Artemia salina is a species of brine shrimp – aquatic crustaceans that are more closely related to Triops and cladocerans than to true shrimp. It belongs to a lineage that does not appear to have changed much in 100 million years.
Artemia salina is native to saline lakes, ponds, and temporary waters (not seas) in the Mediterranean region of Southern Europe, Anatolia, and Northern Africa. Considerable taxonomic confusion exists, and some populations elsewhere have formerly been referred to as this species, but are now recognized as separate species.
