Artemia is a genus of aquatic crustaceans also known as brine shrimp. Artemia, the only genus in the family Artemiidae, has changed little externally since the Triassic period. The first historical record of the existence of Artemia dates back to the first half of the 10th century AD from Urmia Lake, Iran, with an example called by an Iranian geographer an "aquatic dog", although the first unambiguous record is the report and drawings made by Schlösser in 1757 of animals from Lymington, England. Artemia populations are found worldwide in inland saltwater lakes, but not in oceans. Artemia are able to avoid cohabiting with most types of predators, such as fish, by their ability to live in waters of very high salinity (up to 25%).
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 it has become a model organism used to test the toxicity of chemicals. Breeds of Artemia are sold as novelty gifts under the marketing name Sea-Monkeys or Aqua Dragons.
|Artemia salina mating pair – female left, male right|
The Laboratory of Aquaculture & Artemia Reference Center (ARC) at Ghent University possesses the largest known Artemia cyst collection, a cyst bank containing over 1,700 Artemia population samples collected from different locations around the world.
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 synchronisation of these functions. Autotomy, the voluntary shedding or dropping of parts of the body for defence, is also controlled locally along the nervous system. 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.
Brine shrimp can tolerate any levels of salinity from 25‰ to 250‰ (25–250 g/L), with an optimal range of 60‰–100‰, and occupy the ecological niche that can protect them from predators. Physiologically, optimal levels of salinity are about 30–35‰, but due to predators at these salt levels, brine shrimp seldom occur in natural habitats at salinities of less than 60–80‰. Locomotion is achieved by the rhythmic beating of the appendages acting in pairs. Respiration occurs on the surface of the legs through fibrous, feather-like plates (lamellar epipodites)
Males differ from females by having the second antennae markedly enlarged, and modified into clasping organs used in mating. Adult female brine shrimp ovulate approximately every 140 hours. In favourable conditions, the female brine shrimp can produce eggs that almost immediately hatch. While in extreme conditions, such as low oxygen level or salinity above 150‰, female brine shrimp produce eggs with a chorion coating which has a brown colour. These eggs, also known as cysts, are metabolically inactive and can remain in total stasis for two years while in dry oxygen-free conditions, even at temperatures below freezing. This characteristic is called cryptobiosis, meaning "hidden life". While in cryptobiosis, brine shrimp eggs can survive temperatures of liquid air (−190 °C or −310 °F) and a small percentage can survive above boiling temperature (105 °C or 221 °F) for up to two hours. Once placed in briny (salt) water, the eggs hatch within a few hours. The nauplius larvae are less than 0.4 mm in length when they first hatch.
Parthenogenesis is a natural form of reproduction in which growth and development of embryos occur without fertilisation. Thelytoky is a particular form of parthenogenesis in which the development of a female individual occurs from an unfertilised egg. Automixis is a form of thelytoky, but there are different kinds of automixis. The kind of automixis relevant here is one in which two haploid products from the same meiosis combine to form a diploid zygote.
Diploid Artemia parthenogenetica reproduce by automictic parthenogenesis with central fusion (see diagram) and low but nonzero recombination. Central fusion of two of the haploid products of meiosis (see diagram) tends to maintain heterozygosity in transmission of the genome from mother to offspring, and to minimise inbreeding depression. Low crossover recombination during meiosis likely restrains the transition from heterozygosity to homozygosity over successive generations.
In their first stage of development, Artemia do not feed but consume their own energy reserves stored in the cyst. Wild brine shrimp eat microscopic planktonic algae. Cultured brine shrimp can also be fed particulate foods including yeast, wheat flour, soybean powder or egg yolk.
Fish farm owners search for a cost-effective, easy to use, and available food that is preferred by the fish. From cysts, brine shrimp nauplii can readily be used to feed fish and crustacean larvae just after one-day incubation. Instar I (the nauplii that just hatched and with large yolk reserves in their body) and instar II nauplii (the nauplii after first moult and with functional digestive tracts) are more widely used in aquaculture, because they are easy for operation, rich in nutrients, and small, which makes them suitable for feeding fish and crustacean larvae live or after drying.
In pollution research Artemia, the brine shrimp, has had extensive use as a test organism and in some circumstances is an acceptable alternative to the toxicity testing of mammals in the laboratory. The fact that millions of brine shrimp are so easily reared has been an important help in assessing the effects of a large number of environmental pollutants on the shrimps under well controlled experimental conditions.
Overall brine shrimp are abundant, but some populations and localized species do face threats, especially from habitat loss to introduced species. For example, A. franciscana of the Americas has been widely introduced to places outside its native range and is often able to outcompete local species, such as A. salina in the Mediterranean region.
Among the highly localized species are A. urmiana from Lake Urmia in Iran. Once abundant, the species has drastically declined due to drought, leading to fears that it was almost extinct. However, a second population of this species has recently been discovered in the Koyashskoye Salt Lake at the Crimean Peninsula.
A. monica, the species commonly known as Mono Lake brine shrimp, can be found in Mono Lake, Mono County, California. In 1987, Dennis D. Murphy from Stanford University petitioned the United States Fish and Wildlife Service to add A. monica to the endangered species list under the Endangered Species Act (1973). The diversion of water by the Los Angeles Department of Water and Power resulted in rising salinity and concentration of sodium hydroxide in Mono Lake. Despite the presence of trillions of brine shrimp in the lake, the petition contended that the increase in pH would endanger them. The threat to the lake's water levels was addressed by a revision to California State Water Resources Control Board's policy, and the US Fish and Wildlife Service found on 7 September 1995 that the Mono Lake brine shrimp did not warrant listing.
Scientists have taken the eggs of brine shrimp to outer space to test the impact of radiation on life. Brine shrimp cysts were flown on the U.S. Biosatellite II, Apollo 16, and Apollo 17 missions, and on the Russian Bion-3 (Cosmos 782), Bion-5 (Cosmos 1129), Foton 10, and Foton 11 flights. Some of the Russian flights carried European Space Agency experiments.
On Apollo 16 and Apollo 17, the cysts traveled to the Moon and back. The cosmic ray passed through an egg would be detected on the photographic film in their container. Some eggs were kept on Earth as experimental controls to ensure a fair test. Also, as the take-off in a spacecraft involves a lot of shaking and acceleration, one control group of egg cysts was accelerated to seven times the force of gravity and vibrated mechanically from side to side for several minutes so that they could experience the same violence of a rocket take-off. There were 400 eggs in each experimental group. All the egg cysts from the experiment were then placed in salt water to hatch under optimum conditions. As a result, a high sensitivity to cosmic radiation was observed on Artemia salina eggs; 90% of the embryos, which were induced to develop from hit eggs, died at different developmental stages.
Brine shrimp have the ability to produce dormant eggs, known as cysts. This has led to the extensive use of brine shrimp 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.From cysts, brine shrimp nauplii can readily be used to feed to fish and crustacean larvae just after one-day incubation. Instar I (the nauplii that just hatched and with large yolk reserves in their body) and instar II nauplii (the nauplii after first moult and with functional digestive tracts) are more widely used in aquaculture, for the reasons they are easy for operation, nutrients rich, and of small size which makes them suitable for feeding fish and crustacean larvae live or after drying.Aquarium fish feed
Aquarium fish feed is plant or animal material intended for consumption by pet fish kept in aquariums or ponds. Fish foods normally contain macronutrients, trace elements and vitamins necessary to keep captive fish in good health. Approximately 80% of fishkeeping hobbyists feed their fish exclusively prepared foods that most commonly are produced in flake, pellet or tablet form. Pelleted forms, some of which sink rapidly, are often used for larger fish or bottom feeding species such as loaches or catfish. Some fish foods also contain additives such as sex hormones or beta carotene to artificially enhance the color of ornamental fish.Artemia monica
The Mono Lake brine shrimp (Artemia monica) is a species of brine shrimp, endemic to Mono Lake in California, United States.
It is a sibling species of A. franciscana, which is widespread in the Americas and also has been introduced elsewhere. The two are closely related, but completely prevented from interbreeding as they have different water requirements.Artemia parthenogenetica
Artemia parthenogenetica is a species of brine shrimp – aquatic crustaceans belonging to a different class, the Branchiopoda, than the true shrimps.Artemia salina
Artemia salina is a species of brine shrimp – aquatic crustaceans that are more closely related to Triops and cladocerans than to true shrimp. It is a very old species that does not appear to have changed in 100 million years.
A. 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.Commercial fish feed
Manufactured feeds are an important part of modern commercial aquaculture, providing the balanced nutrition needed by farmed fish. The feeds, in the form of granules or pellets, provide the nutrition in a stable and concentrated form, enabling the fish to feed efficiently and grow to their full potential.
Many of the fish farmed more intensively around the world today are carnivorous, for example Atlantic salmon, trout, sea bass, and turbot. In the development of modern aquaculture, starting in the 1970s, fishmeal and fish oil were key components of the feeds for these species. They are combined with other ingredients such as vegetable proteins, cereal grains, vitamins and minerals and formed into feed pellets. Wheat, for example, is widely used as it helps to bind the ingredients in the pellets.Other forms of fish feed being used include feeds made entirely with vegetable materials for species such as carp, moist feeds preferred by some species (easier to make but more difficult to store), and trash fish — that is fish caught and fed directly to larger species being raised in aquaculture pens.Corydoras punctatus
Corydoras punctatus (spotted catfish) is a species of catfish found in the Suriname river basin and Iracoubo river basin in tropical Suriname and French Guiana. The species is rarely seen. It is hard to tell the sex of the fish until they are an adult. The species can breed easily. The species eat many foods including shrimp pellets, blood worms, brine shrimp, and pre-soaked flake food. Corydoras punctatus is a social fish.Dawada
The Dawada (Duwwud, Dawwada) is an Afro-Arab ethnic group from the Fezzan region of southern Libya. They live around the Gabraoun oasis, at the town of Murzuk, where they harvest brine shrimp in the salty lakes. They dry the brine shrimp and sell them to caravans. The name Dawada means "worm-folk" in Arabic due to this practice. The appearance of the Dawada is distinctive and has been likened to the Khoisan, perhaps a relict population. They are mostly an endogamic group which rarely marry outside of their tribe. They speak an Arabic dialect.Eubranchipus
Eubranchipus is a genus of brine shrimp and fairy shrimp in the family Chirocephalidae. There are about 16 described species in Eubranchipus.Great Salt Lake
The Great Salt Lake, located in the northern part of the U.S. state of Utah, is the largest salt water lake in the Western Hemisphere, and the eighth-largest terminal lake in the world. In an average year the lake covers an area of around 1,700 square miles (4,400 km2), but the lake's size fluctuates substantially due to its shallowness. For instance, in 1963 it reached its lowest recorded size at 950 square miles (2,460 km²), but in 1988 the surface area was at the historic high of 3,300 square miles (8,500 km2). In terms of surface area, it is the largest lake in the United States that is not part of the Great Lakes region.
The lake is the largest remnant of Lake Bonneville, a prehistoric pluvial lake that once covered much of western Utah. The three major tributaries to the lake, the Jordan, Weber, and Bear rivers together deposit around 1.1 million tons of minerals in the lake each year. As it is endorheic (has no outlet besides evaporation), it has very high salinity (far saltier than seawater) and its mineral content is steadily increasing. Due to the high density resulting from its mineral content, swimming in the Great Salt Lake is similar to floating. Its shallow, warm waters cause frequent, sometimes heavy lake-effect snows from late fall through spring.
Although it has been called "America's Dead Sea", the lake provides habitat for millions of native birds, brine shrimp, shorebirds, and waterfowl, including the largest staging population of Wilson's phalarope in the world.Hutt Lagoon
Hutt Lagoon is a salt lake located near the coast just north of the mouth of the Hutt River, in the Mid West region of Western Australia.Lake Abert
Lake Abert (also known as Abert Lake) is a large, shallow, alkali lake in Lake County, Oregon, United States. It is approximately 15 miles (24 km) long and 7 miles (11 km) wide at its widest point. It is located 3 miles (4.8 km) northeast of the small, unincorporated community of Valley Falls, Oregon. The lake was named in honor of Colonel John James Abert by explorer John C. Fremont during his 1843 expedition into Central Oregon. No fish live in the alkaline waters of the lake; however, its dense population of brine shrimp supports a variety of shorebirds. The lake is also an important stop on the bird migration route known as the Pacific flyway.Little Manitou Lake (Saskatchewan)
Little Manitou Lake is a small saltwater lake about 120 kilometres south-east of Saskatoon, Canada. The lake was formed by receding glaciers during the most recent ice age. It is fed by underground springs, and has a mineral content high in sodium, magnesium and potassium salts due to it being a terminal lake. The salt content of the water (180 g/L) gives it a salinity about half of that of the Dead Sea (300-400 ppt), allowing bathers to float easily. There is no fishing, because the high salt content of the water supports little other than brine shrimp.Misgurnus fossilis
Misgurnus fossilis is a species of loach in the genus Misgurnus. It is commonly known as European weatherfish or European weather loach, due to its activity patterns changing when air pressure rises or falls. If there is a sudden change in barometric pressure, the weatherfish comes to the surface and swims about excitedly. In water with a low oxygen content it gulps air; it extracts oxygen through its intestinal mucous membrane, which has a complex system of blood vessels. It feeds on thawed frozen blood worms, small fish, brine shrimp, earthworms and some vegetables. It is quite an active loach and can grow to a length of 30 cm.Osmoprotectant
Osmoprotectants or compatible solutes are small organic molecules with neutral charge and low toxicity at high concentrations that act as osmolytes and help organisms survive extreme osmotic stress. Osmoprotectants can be placed in three chemical classes: betaines and associated molecules, sugars and polyols, and amino acids.These molecules accumulate in cells and balance the osmotic difference between the cell's surroundings and the cytosol. In plants, their accumulation can increase survival during stresses such as drought. In extreme cases, such as in bdelloid rotifers, tardigrades, brine shrimp, and nematodes, these molecules can allow cells to survive being completely dried out and let them enter a state of suspended animation called cryptobiosis.Intercellular osmoprotectant concentrations are regulated in response to environmental conditions such as osmolarity and temperature via regulation of specific transcription factors and transporters. They have been shown to play a protective role by maintaining enzyme activity through freeze-thaw cycles and at higher temperatures. It is currently believed that they function by stabilizing protein structures by promoting preferential exclusion from the water layers on the surface of hydrated proteins. This favors the native conformation and displaces inorganic salts that would otherwise cause misfolding.Plant perception (paranormal)
Plant perception or biocommunication is the paranormal idea that plants are sentient, that they respond to humans in a manner that amounts to ESP, and that they experience pain and fear. The idea is not accepted by the scientific community, as plants lack nervous systems. Paranormal claims in regard to plant perception are considered to be pseudoscience by many in the scientific community.The idea is distinct from measured plant perception and chemical communication.Rhinogobius duospilus
Rhinogobius duospilus is a species of goby native to China and Vietnam where they can be found in fresh or brackish waters. This species can reach a length of 4.5 centimetres (1.8 in) TL. In their natural environment these fish consume larvae or other similar creatures, but they can be fed brine shrimp or blood worms.Sea-Monkeys
Sea-Monkeys are a hybrid version of brine shrimp—a group of crustaceans that undergo cryptobiosis. Sea Monkeys are scientifically classified as Artemia NYOS (New York Ocean Science), while brine shrimp are classified as Artemia salina. Sea Monkeys are sold in hatching kits as novelty aquarium pets. Developed in the United States in 1957, at this point being just part of the Artemia salina species, by Harold von Braunhut, the product was heavily marketed, especially in comic books, and remains a presence in popular culture.Shrimp mix
Shrimp mix, also known as European shrimp mix, is a frozen fish feed used for fish with special dietary requirements, e.g. Tropheus, which are difficult to maintain using normal fish feed. The basic version is intended for herbivorous fish and is made by blending equal amounts of whole shrimp and green peas to a smooth paste, adding a vitamin supplement, and using either agar-agar or gelatin as binder. There are numerous variants tailored to the specific needs of different species. Common variants replace part of the shrimp or peas with fish meat, spinach, spirulina, or mussel meat, and add astaxanthin, ascorbic acid, or garlic.