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Mundafan
Mundafan was a former lake in Saudi Arabia, within presently desert-like areas. It formed during the Pleistocene and Holocene, when orbitally mediated changes in climate increased monsoon precipitation in the peninsula, allowing runoff to form a lake with a maximum area of . It was populated by fishes and surrounded by reeds and savanna, which supported human populations. Geography and lake Mundafan is a lies in the Najran Province of Saudi Arabia, southwest of the Rub' al Khali desert. The climate of the region is arid to hyperarid, with sand and stone deserts dominating the landscape. The name ar, Ramlat al-Mundafan means "the buried sands". The perennial lake had an elongated shape in northwest-southeast direction and reached a maximum depth of and extent of during stages of high water levels, making it one of the largest former lakes of Arabia. It is possible that it was not one contiguous water body, but rather several separate lakes or an extended wetland. The lake wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Former Lake
A former is an object, such as a template, Gauge block, gauge or cutting Die (manufacturing), die, which is used to form something such as a boat's Hull (watercraft), hull. Typically, a former gives shape to a structure that may have complex curvature. A former may become an integral part of the finished structure, as in an aircraft fuselage, or it may be removable, being using in the construction process and then discarded or re-used. Aircraft formers Formers are used in the construction of aircraft fuselage, of which a typical fuselage has a series from the nose to the empennage, typically perpendicular to the Flight control surfaces#Longitudinal_axis, longitudinal axis of the aircraft. The primary purpose of formers is to establish the shape of the fuselage and reduce the column length of stringers to prevent instability. Formers are typically attached to longerons, which support the skin of the aircraft. The "former-and-longeron" technique (also called stations and string ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Freshwater
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 wa ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Marsh
A marsh is a wetland that is dominated by herbaceous rather than woody plant species.Keddy, P.A. 2010. Wetland Ecology: Principles and Conservation (2nd edition). Cambridge University Press, Cambridge, UK. 497 p Marshes can often be found at the edges of lakes and streams, where they form a transition between the aquatic and terrestrial ecosystems. They are often dominated by grasses, rushes or reeds. If woody plants are present they tend to be low-growing shrubs, and the marsh is sometimes called a carr. This form of vegetation is what differentiates marshes from other types of wetland such as swamps, which are dominated by trees, and mires, which are wetlands that have accumulated deposits of acidic peat. Marshes provide habitats for many kinds of invertebrates, fish, amphibians, waterfowl and aquatic mammals. This biological productivity means that marshes contain 0.1% of global sequestered terrestrial carbon. Moreover, they have an outsized influence on climate resi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sedge
The Cyperaceae are a family of graminoid (grass-like), monocotyledonous flowering plants known as sedges. The family is large, with some 5,500 known species described in about 90 genera, the largest being the "true sedges" genus ''Carex'' with over 2,000 species. These species are widely distributed, with the centers of diversity for the group occurring in tropical Asia and tropical South America. While sedges may be found growing in almost all environments, many are associated with wetlands, or with poor soils. Ecological communities dominated by sedges are known as sedgelands or sedge meadows. Some species superficially resemble the closely related rushes and the more distantly related grasses. Features distinguishing members of the sedge family from grasses or rushes are stems with triangular cross-sections (with occasional exceptions, a notable example being the tule which has a round cross-section) and leaves that are spirally arranged in three ranks. In comparison, g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Typha
''Typha'' is a genus of about 30 species of monocotyledonous flowering plants in the family Typhaceae. These plants have a variety of common names, in British English as bulrush or reedmace, in American English as reed, cattail, or punks, in Australia as cumbungi or bulrush, in Canada as bulrush or cattail, and in New Zealand as raupo. Other taxa of plants may be known as bulrush, including some sedges in ''Scirpus'' and related genera. The genus is largely distributed in the Northern Hemisphere, where it is found in a variety of wetland habitats. The rhizomes are edible. Evidence of preserved starch grains on grinding stones suggests they were already eaten in Europe 30,000 years ago. Description ''Typha'' are aquatic or semi-aquatic, rhizomatous, herbaceous perennial plants. The leaves are glabrous (hairless), linear, alternate and mostly basal on a simple, jointless stem that bears the flowering spikes. The plants are monoecious, with unisexual flowers that develop in ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phragmites
''Phragmites'' () is a genus of four species of large perennial reed grasses found in wetlands throughout temperate and tropical regions of the world. Taxonomy The World Checklist of Selected Plant Families, maintained by Kew Garden in London, accepts the following four species: * ''Phragmites australis'' ( Cav.) Trin. ex Steud. – cosmopolitan * ''Phragmites japonicus'' Steud. – Japan, Korea, Ryukyu Islands, Russian Far East * ''Phragmites karka'' ( Retz.) Trin. ex Steud. – tropical Africa, southern Asia, Australia, some Pacific Islands, invasive in New Zealand * ''Phragmites mauritianus'' Kunth – central + southern Africa, Madagascar, Mauritius The cosmopolitan common reed has the generally accepted botanical name ''Phragmites australis''. (Cav.) Trin. ex Steud. About 130 other synonyms have been proposed. Examples include ''Phragmites communis'' Trin., ''Arundo phragmites'' L., and ''Phragmites vulgaris'' (Lam.) Crép. (illegitimate name). Wildlife in reed beds ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Alga
Algae (; singular alga ) is an informal term for a large and diverse group of photosynthetic eukaryotic organisms. It is a polyphyletic grouping that includes species from multiple distinct clades. Included organisms range from unicellular microalgae, such as ''Chlorella,'' ''Prototheca'' and the diatoms, to multicellular forms, such as the giant kelp, a large brown alga which may grow up to in length. Most are aquatic and autotrophic (they generate food internally) and lack many of the distinct cell and tissue types, such as stomata, xylem and phloem that are found in land plants. The largest and most complex marine algae are called seaweeds, while the most complex freshwater forms are the ''Charophyta'', a division of green algae which includes, for example, ''Spirogyra'' and stoneworts. No definition of algae is generally accepted. One definition is that algae "have chlorophyll ''a'' as their primary photosynthetic pigment and lack a sterile covering of cells around t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Stonewort
Charales is an order of freshwater green algae in the division Charophyta, class Charophyceae, commonly known as stoneworts. Depending on the treatment of the genus ''Nitellopsis'', living (extant) species are placed into either one family ( Characeae) or two (Characeae and Feistiellaceae). Further families are used for fossil members of the order. Linnaeus established the genus ''Chara (alga), Chara'' in 1753. Taxonomy The higher level classification of green algae was unsettled . AlgaeBase places Charales within the class Charophyceae and its Circumscription (taxonomy), circumscription of the Phylum, division Charophyta. Families The number of families and their division into genera varies. , AlgaeBase accepts two families containing some extant species and four families containing only fossil species: * Characeae S.F.Gray * Feistiellaceae Schudack *†Aclistocharaceae X.G.Zhou (may be included in Characeae) *†Atopocharaceae R.E.Peck (may be included in Clavatoraceae) *â ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sponge
Sponges, the members of the phylum Porifera (; meaning 'pore bearer'), are a basal animal clade as a sister of the diploblasts. They are multicellular organisms that have bodies full of pores and channels allowing water to circulate through them, consisting of jelly-like mesohyl sandwiched between two thin layers of cells. Sponges have unspecialized cells that can transform into other types and that often migrate between the main cell layers and the mesohyl in the process. Sponges do not have nervous, digestive or circulatory systems. Instead, most rely on maintaining a constant water flow through their bodies to obtain food and oxygen and to remove wastes. Sponges were first to branch off the evolutionary tree from the last common ancestor of all animals, making them the sister group of all other animals. Etymology The term ''sponge'' derives from the Ancient Greek word ( 'sponge'). Overview Sponges are similar to other animals in that they are multicellular, he ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Radix
In a positional numeral system, the radix or base is the number of unique digits, including the digit zero, used to represent numbers. For example, for the decimal/denary system (the most common system in use today) the radix (base number) is ten, because it uses the ten digits from 0 through 9. In any standard positional numeral system, a number is conventionally written as with ''x'' as the string of digits and ''y'' as its base, although for base ten the subscript is usually assumed (and omitted, together with the pair of parentheses), as it is the most common way to express value. For example, (the decimal system is implied in the latter) and represents the number one hundred, while (100)2 (in the binary system with base 2) represents the number four. Etymology ''Radix'' is a Latin word for "root". ''Root'' can be considered a synonym for ''base,'' in the arithmetical sense. In numeral systems In the system with radix 13, for example, a string of digits such as 398 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Biomphalaria
''Biomphalaria'' is a genus of air-breathing freshwater snails, aquatic animal, aquatic pulmonate gastropod mollusks in the family (biology), family Planorbidae, the sheep, ram's horn snails and their allies.MolluscaBase (2018). Biomphalaria Preston, 1910. Accessed through: World Register of Marine Species at: http://www.marinespecies.org/aphia.php?p=taxdetails&id=718742 on 2018-02-13 ''Biomphalaria'' is the type genus of the tribe Biomphalariini. ''Taphius'' is a synonym for ''Biomphalaria''. The shell of this species, like all planorbids is sinistral in coiling, but is carried upside down and thus appears to be dextral. Species As of 2008 there were recognized 34 extant species in the genus ''Biomphalaria'' in total (22 American species and 12 Old World species). There were also described number of fossil ''Biomphalaria'' species. American species include: # ''Biomphalaria amazonica'' Paraense, 1966 # ''Biomphalaria andecola'' (d'Orbigny, 1835) # ''Biomphalaria cousini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Snail
A snail is, in loose terms, a shelled gastropod. The name is most often applied to land snails, terrestrial pulmonate gastropod molluscs. However, the common name ''snail'' is also used for most of the members of the molluscan class Gastropoda that have a coiled shell that is large enough for the animal to retract completely into. When the word "snail" is used in this most general sense, it includes not just land snails but also numerous species of sea snails and freshwater snails. Gastropods that naturally lack a shell, or have only an internal shell, are mostly called '' slugs'', and land snails that have only a very small shell (that they cannot retract into) are often called ''semi-slugs''. Snails have considerable human relevance, including as food items, as pests, and as vectors of disease, and their shells are used as decorative objects and are incorporated into jewelry. The snail has also had some cultural significance, tending to be associated with lethargy. The sn ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
