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Daphnia Longispina
''Daphnia longispina'' is a planktonic crustacean of the family Daphniidae, a cladoceran freshwater water flea. It is native to Eurasia. ''D. longispina'' is similar in size and sometimes confused with the often sympatric '' D. pulex'' (a very common species), but much smaller than '' D. magna''. ''D. longispina'' is found in a wide range of standing freshwater bodies from small, ephemeral rock-pools to large lakes. Life history Like all ''Daphnia'' species, ''D. longispina'' is a filter feeder, collecting particles of about 2 to 40 µm suspended in the water. The main food are green algae. At 20 °C maturity is reached within about 6 to 12 days, followed by a period of regular reproduction in about 3-4 day intervals. ''D. longispina'' reproduces either asexually (''parthenogenesis'') or sexually. For the later, females need to produce sons asexually. The same or other females can switch at any moment from asexual to sexual reproduction, but producing haploid eggs, whi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Otto Friedrich Müller
Otto Friedrich Müller, also known as Otto Friedrich Mueller (2 November 1730 – 26 December 1784) was a Danish naturalist and scientific illustrator. Biography Müller was born in Copenhagen. He was educated for the church, became tutor to a young nobleman, and after several years' travel with him, settled in Copenhagen in 1767, and married a lady of wealth. His first important works, ''Fauna Insectorum Friedrichsdaliana'' (Leipzig, 1764), and ''Flora Friedrichsdaliana'' (Strasbourg, 1767), giving accounts of the insects and flora of the estate of Frederiksdal, near Copenhagen, recommended him to Frederick V of Denmark, by whom he was employed to continue the ''Flora Danica'' a comprehensive atlas of the flora of Denmark. Müller added two volumes to the three published by Georg Christian Oeder since 1761. The study of invertebrates began to occupy his attention almost exclusively, and in 1771 he produced a work in German on “Certain Worms inhabiting Fresh and Salt Water, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Parthenogenesis
Parthenogenesis (; from the Greek grc, παρθένος, translit=parthénos, lit=virgin, label=none + grc, γένεσις, translit=génesis, lit=creation, label=none) is a natural form of asexual reproduction in which growth and development of embryos occur in a gamete (egg or sperm) without combining with another gamete (e.g., egg and sperm fusing). In animals, parthenogenesis means development of an embryo from an unfertilized Gametophyte, egg cell. In plants, parthenogenesis is a component process of apomixis. In algae, parthenogenesis can mean the development of an embryo from either an individual sperm or an individual egg. Parthenogenesis occurs naturally in some plants, algae, invertebrate animal species (including nematodes, some tardigrades, water fleas, some scorpions, aphids, some mites, some bees, some Phasmatodea and parasitic wasps) and a few vertebrates (such as some fish, amphibians, reptiles and birds). This type of reproduction has been induced artificially ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Freshwater Crustaceans Of Europe
Fresh water or freshwater is any naturally occurring liquid or frozen water containing low concentrations of dissolved salts and other total dissolved solids. Although the term specifically excludes seawater and brackish water, it does include non- salty mineral-rich waters such as chalybeate springs. Fresh water may encompass frozen and meltwater in ice sheets, ice caps, glaciers, snowfields and icebergs, natural precipitations such as rainfall, snowfall, hail/ sleet and graupel, and surface runoffs that form inland bodies of water such as wetlands, ponds, lakes, rivers, streams, as well as groundwater contained in aquifers, subterranean rivers and lakes. Fresh water is the water resource that is of the most and immediate use to humans. Water is critical to the survival of all living organisms. Many organisms can thrive on salt water, but the great majority of higher plants and most insects, amphibians, reptiles, mammals and birds need fresh water to survive. Fresh water i ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Cladocera
The Diplostraca or Cladocera, commonly known as water fleas, are a superorder of small crustaceans that feed on microscopic chunks of organic matter (excluding some predatory forms). Over 1000 species have been recognised so far, with many more undescribed. The oldest fossils of diplostracans date to the Jurassic, though their modern morphology suggests that they originated substantially earlier, during the Paleozoic. Some have also adapted to a life in the ocean, the only members of Branchiopoda to do so, even if several anostracans live in hypersaline lakes. Most are long, with a down-turned head with a single median compound eye, and a carapace covering the apparently unsegmented thorax and abdomen. Most species show cyclical parthenogenesis, where asexual reproduction is occasionally supplemented by sexual reproduction, which produces resting eggs that allow the species to survive harsh conditions and disperse to distant habitats. Description They are mostly long, with t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oxford University Press
Oxford University Press (OUP) is the university press of the University of Oxford. It is the largest university press in the world, and its printing history dates back to the 1480s. Having been officially granted the legal right to print books by decree in 1586, it is the second oldest university press after Cambridge University Press. It is a department of the University of Oxford and is governed by a group of 15 academics known as the Delegates of the Press, who are appointed by the vice-chancellor of the University of Oxford. The Delegates of the Press are led by the Secretary to the Delegates, who serves as OUP's chief executive and as its major representative on other university bodies. Oxford University Press has had a similar governance structure since the 17th century. The press is located on Walton Street, Oxford, opposite Somerville College, in the inner suburb of Jericho. For the last 500 years, OUP has primarily focused on the publication of pedagogical texts and ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Daphnia Cucullata
''Daphnia'' is a genus of small planktonic crustaceans, in length. ''Daphnia'' are members of the order Anomopoda, and are one of the several small aquatic crustaceans commonly called water fleas because their saltatory swimming style resembles the movements of fleas. ''Daphnia'' spp. live in various aquatic environments ranging from acidic swamps to freshwater lakes and ponds. The two most commonly found species of ''Daphnia'' are '' D. pulex'' (small and most common) and '' D. magna'' (large). They are often associated with a related genus in the order Cladocera: ''Moina'', which is in the Moinidae family instead of the Daphniidae, and is much smaller than ''D. pulex'' (roughly half the maximum length). Appearance and characteristics The body of a ''Daphnia'' species is usually long, and is divided into segments, although this division is not visible. The head is fused, and is generally bent down towards the body with a visible notch separating the two. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Daphnia Galeata
''Daphnia galeata'' is a small species of planktonic crustaceans. It lives in freshwater environments across a large area of the Northern Hemisphere, mostly in lakes. ''D. galeata'' comprises two subspecies: ''D. g. galeata'', found in the Old World, and ''D. g. mendotae'', named after Lake Mendota near Madison, Wisconsin, in the New World. ''D. g. mendotae'' may be a homoploid hybrid taxon. In the lower Great Lakes The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes in the mid-east region of North America that connect to the Atlantic Ocean via the Saint Lawrence River. There are five lakes ..., the populations are mostly hybrids of the European and American subspecies. References Cladocera Freshwater crustaceans Crustaceans described in 1864 {{Branchiopoda-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Ephippia
Ephippia (singular: ephippium) are winter or dry-season eggs of the various species of small crustacean in the order Cladocera (within the Branchiopoda); they are provided with an extra shell layer, which preserves and protects the resting stages inside from harsh environmental conditions until the more favorable times, such as spring, when the reproductive cycle is able to take place once again. Ephippia are part of the back of a mother carrying them until they are fully developed. After molting, the ephippium stays in the water, or in the soil of dried puddles, small ponds, and vernal pools. The resting stages are often called eggs, but are in fact embryos with arrested development. Ephippia can rest for many years before the embryo resumes development upon an appropriate hatching stimulus. See also * ''Bythotrephes longimanus'' (invasive species) * ''Cercopagis pengoi'' (invasive species) * ''Daphnia ** ''Daphnia longispina'' ** ''Daphnia lumholtzi'' (invasive species) * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Daphnia Magna
''Daphnia magna'' is a small planktonic crustacean (adult length 1.5–5.0 mm) that belongs to the subclass Phyllopoda. Description ''D. magna'' is a typical water flea of the genus ''Daphnia''. The females reach up to 5 mm in size, the males about 2 mm, thus they are among the largest species in the genus. The body is protected by a translucent carapace made of chitin, a transparent polysaccharide. It has a ventral opening and five pairs of thoracic limbs, used to help the filtering process. Spike rows run along the back of the carapace. The intestine is hook-shaped and has two digestive ceca. The head has two antennae and a large compound eye. Adult females can be distinguished from those of otherwise similar species such as '' D. pulex'' by the absence of a comb on the abdominal claw and the presence of two distinct combs on the abdomen. The males are smaller than the females and have larger first antennas, a diagnostic feature that distinguishes them from s ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Female Daphnia Longispina Carrying A Resting Egg ("ephippium")
Female (symbol: ♀) is the sex of an organism that produces the large non-motile ova (egg cells), the type of gamete (sex cell) that fuses with the male gamete during sexual reproduction. A female has larger gametes than a male. Females and males are results of the anisogamous reproduction system, wherein gametes are of different sizes, unlike isogamy where they are the same size. The exact mechanism of female gamete evolution remains unknown. In species that have males and females, sex-determination may be based on either sex chromosomes, or environmental conditions. Most female mammals, including female humans, have two X chromosomes. Female characteristics vary between different species with some species having pronounced secondary female sex characteristics, such as the presence of pronounced mammary glands in mammals. In humans, the word ''female'' can also be used to refer to gender in the social sense of gender role or gender identity. Etymology and usage The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Daphnia Pulex
''Daphnia pulex'' is the most common species of water flea. It has a cosmopolitan distribution: the species is found throughout the Americas, Europe, and Australia. It is a model species, and was the first crustacean to have its genome sequenced. Description ''D. pulex'' is an arthropod whose body segments are difficult to distinguish. It can only be recognised by its appendages (only ever one pair per segment), and by studying its internal anatomy. The head is distinct and is made up of six segments, which are fused together even as an embryo. It bears the mouthparts, and two pairs of antennae, the second pair of which is enlarged into powerful organs used for swimming. No clear division is seen between the thorax and abdomen, which collectively bear five pairs of appendages. The shell surrounding the animal extends posteriorly into a spine. Like most other ''Daphnia'' species, ''D. pulex'' reproduces by cyclical parthenogenesis, alternating between sexual and asexual reprodu ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Eurasia
Eurasia (, ) is the largest continental area on Earth, comprising all of Europe and Asia. Primarily in the Northern and Eastern Hemispheres, it spans from the British Isles and the Iberian Peninsula in the west to the Japanese archipelago and the Russian Far East to the east. The continental landmass is bordered by the Atlantic Ocean and Africa to the west, the Pacific Ocean to the east, the Arctic Ocean to the north, and by Africa, the Mediterranean Sea, and the Indian Ocean to the south. The division between Europe and Asia as two continents is a historical social construct, as many of their borders are over land; thus, in some parts of the world, Eurasia is recognized as the largest of the six, five, or four continents on Earth. In geology, Eurasia is often considered as a single rigid megablock. However, the rigidity of Eurasia is debated based on paleomagnetic data. Eurasia covers around , or around 36.2% of the Earth's total land area. It is also home to the largest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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