Daphnia magna is a species

Species

In biology, a species is one of the basic units of biological classification and a taxonomic rank. A species is often defined as a group of organisms capable of interbreeding and producing fertile offspring. While in many cases this definition is adequate, more precise or differing measures are...

 of Daphnia

Daphnia

Daphnia are small, planktonic crustaceans, between 0.2 and 5 mm in length. Daphnia are members of the order Cladocera, and are one of the several small aquatic crustaceans commonly called water fleas because of their saltatory swimming style...

(a cladocera

Cladocera

Cladocera is an order of small crustaceans commonly called water fleas. Around 620 species have been recognised so far, with many more undescribed. They are ubiquitous in inland aquatic habitats, but rare in the oceans. Most are long, with a down-turned head, and a carapace covering the apparently...

n freshwater

Fresh Water

Fresh Water is the debut album by Australian rock and blues singer Alison McCallum, released in 1972. Rare for an Australian artist at the time, it came in a gatefold sleeve...

 water flea) which is native to northern and western North America

North America

North America is a continent wholly within the Northern Hemisphere and almost wholly within the Western Hemisphere. It is also considered a northern subcontinent of the Americas...

. It is also widely distributed in Eurasia

Eurasia

Eurasia is a continent or supercontinent comprising the traditional continents of Europe and Asia ; covering about 52,990,000 km2 or about 10.6% of the Earth's surface located primarily in the eastern and northern hemispheres...

 and in some regions of Africa

Africa

Africa is the world's second largest and second most populous continent, after Asia. At about 30.2 million km² including adjacent islands, it covers 6% of the Earth's total surface area and 20.4% of the total land area...

.

Laboratory animal

Domesticated, it is widely used as a laboratory animal for testing ecotoxicity

Ecotoxicity

Ecotoxicity, the subject of study of the field of ecotoxicology refers to the potential for biological, chemical or physical stressors to affect ecosystems...

 starting with Einar Naumann

Einar Naumann

Einar Christian Leonard Naumann was an assistant professor of botany and limnology at the University of Lund. Naumann worked during the summers at the Fishery Station in Aneboda , where he established a field laboratory of the Limnological Institute in Lund .In 1921 he suggested the establishment of...

 in 1934. As Anderson stated in 1944:

The use of Daphnia magna as an experimental animal for such purposes is advantageous in many respects. Daphnids are small, reaching a size of five mm, so that a great many can be reared in a small space. They have a relatively short life span, which reaches a maximum of about two months when they are reared at 25°C. Daphnids are easy to culture, requiring only water containing bacteria or their equivalent for food. They can be grown individually in small bottles or in mass culture in large aquaria. They mature early, giving birth to young within their first week of life. After their first brood, they give rise to new broods every two or three days throughout the remainder of their lives. An average of twenty or more young may be produced in each brood. Each female who lives to a ripe old age can bear four hundred or more offspring. Again, all the young from one female are genetically like the mother if produced parthenogenically, and reproduction can be limited to parthenogenesis if the proper conditions are maintained. Further, daphnids are representatives of a class of animals that serve as food for many fish, especially while the fish are young. Fishes do not remain long in waters where their food supply has been destroyed, even though the fishes may not be affected directly. For these reasons daphnids should prove satisfactory for testing waters for toxic materials.

D. magna is specified to be used in the OECD Guidelines for the Testing of Chemicals

OECD Guidelines for the Testing of Chemicals

OECD Guidelines for the Testing of Chemicals are a set of internationally-accepted specifications for the testing of chemicals decided on by the Organisation for Economic Co-operation and Development . They were first published in 1981...

, Tests No. 202 "Daphnia sp., Acute Immobilisation Test and Reproduction Test", and Test No. 211 "Daphnia magna Reproduction Test". Test No. 202 is a 48 hour acute toxicity

Acute toxicity

Acute toxicity describes the adverse effects of a substance that result either from a single exposure or from multiple exposures in a short space of time...

 study, where young Daphnia are exposed to varying concentrations of the substance under test and the EC₅₀

EC50

The term half maximal effective concentration refers to the concentration of a drug, antibody or toxicant which induces a response halfway between the baseline and maximum after some specified exposure time...

 determined. Other Daphnia species than D. magna may occasionally be used, but labs mostly use D. magna as standard

Standard (metrology)

In the science of measurement, a standard is an object, system, or experiment that bears a defined relationship to a unit of measurement of a physical quantity. Standards are the fundamental reference for a system of weights and measures, against which all other measuring devices are compared...

.

Test No. 211 is a 21 day chronic toxicity

Chronic toxicity

Chronic toxicity is a property of a substance that has toxic effects on a living organism, when that organism is exposed to the substance continuously or repeatedly. Compared with acute toxicity.Two distinct situations need to be considered:...

 test, at the end of which, the total number of living offspring produced per parent animal alive at the end of the test is assessed, in order to determine the lowest observed effect concentration of the test substance.

Other uses

As it is easy to culture, D. magna is widely grown as fish food

Fish food

Aquarium fish feed is plant or animal material intended for consumption by pet fish kept in aquariums or ponds. Fish foods normally contain macro nutrients, trace elements and vitamins necessary to keep captive fish in good health. Approximately 80% of fishkeeping hobbyists feed their fish...

.

A recent study has postulated that Daphnia magna eats the spores of the devastating chytrid fungus Batrachochytrium dendrobatidis

Batrachochytrium dendrobatidis

Batrachochytrium dendrobatidis is a chytrid fungus that causes the disease chytridiomycosis. In the decade after it was first discovered in amphibians in 1998, the disease devastated amphibian populations around the world, in a global decline towards multiple extinctions, part of the Holocene...