Daphnia


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Related to Daphnia: Daphnia pulex

Daphnia

 

a genus of freshwater animals of the suborder Cladocera. Daphnia measure 1–3 mm and have a transparent, oval, chitinous shell, whose valves are united on the dorsal side and open in the form of slits on the ventral side. Daphnia are dioecious. Some summer generations are represented only by females, which reproduce parthenogenetically. In the fall, males also appear; fertilization occurs, the females deposit one or two fertilized eggs, which are covered with a thick membrane. These eggs hibernate; in the spring females develop from them. There are a total of 26 species, 14 in the USSR; they are distributed everywhere, except in polar regions. Daphnia live in lakes, ponds, temporary bodies of water, and the backwaters of slow-moving rivers. They feed on bacteria, unicellular algae, protozoans, and the smallest particles of plant detritus. Daphnia serve as food for recently hatched and young fish (they are raised for this purpose in fisheries). Daphnia are intermediate hosts of some worms that in their adult form parasitize various vertebrates, including domestic ducks.

References in periodicals archive ?
In the study, the researchers exposed Daphnia to 0.
The idea to send Daphnia to space has been thought up by students from Rhondda Cynon Taff and their project was selected at the end of the Mission Discovery programme at King's College London by a team of scientists led by NASA Space Shuttle Commander Ken Ham.
Just a few years ago, biologists were guessing that asexual Daphnia lineages could be millions of years old, and most recent estimates put it at more than 100,000 years, but new calculations for the molecular evolutionary rates of the two chromosomes implicated in asexuality date the establishment and spread of the asexual lineage to just 1,250 years ago.
This study investigated how methylmercury effects Daphnia pulex in the presence of predatory stress chemical.
It should be noted that Daphnia as a model organism is also used in other scientific disciplines, including chemistry and physiology.
Aquatic toxicity testing is performed using aquatic species, while for regulatory testing of ecotoxicological hazard of pure chemicals the following test species are used: fish (OECD Guideline 203), Daphnia (OECD Guideline 202), algae (OECD Guideline 201).
The LC50 value for glyphosate (the active ingredient in Roundup[R]) (Relyea 2005) is relatively high (4,000 [micro]g/L for Daphnia magna), indicating that it poses minimal risk to aquatic invertebrates.
Spike in Daphnia population as the first generation gives birth;
and Daphnia magna (Crustacea) died within 5 to 8 days after exposure to a concentration of 10 ppm of NeemAzal insecticide (23).
In the present investigation the above Mathematical model is put to test by employing a real case data of two co-existing species of Daphnia [Data is taken from "Competition &Co-existence of species"--A.
Isopropyl alcohol and club soda are both highly suitable agents to test in a Daphnia heart rate lab.