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Margaritifera Falcata
The western pearlshell (''Margaritifera falcata'') is a species of freshwater bivalve, a pearl mussel, a bivalve mollusk in the family Margaritiferidae. This species can be found only in the United States and Canada, where it occurs mostly west of the Rocky Mountains. Distribution This species of pearl mussel is found in Pacific drainages from California north to British Columbia and southern Alaska.Clarke, A. H. 1981. ''The Freshwater Molluscs of Canada''. National Museum of Natural Sciences, National Museums of Canada, Ottawa. 446 pp.Frest, T.J. and E. J. Johannes. 1995. Interior Columbia Basin mollusk species of special concern. Final report to the Interior Columbia Basin Ecosystem Management Project, Walla Walla, WA. Contract #43-0E00-4-9112. 274 pp. plus appendices. Some scientists consider a number of the coastal and large river populations of this species to be already extirpated, nearly extirpated, or declining rapidly.Brim Box, K., J. Howard, D. Wolf, C. O'Brian, D. Nez, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Augustus Addison Gould
Augustus Addison Gould (April 23, 1805 – September 15, 1866) was an American conchologist and malacologist. Biography Born in New Ipswich, New Hampshire, he was the son of music teacher Nathaniel Duren Gould (1781–1864) who was also noted for his penmanship. Physician He graduated from Harvard College in 1825, and took his degree of doctor of medicine in 1830. "Establishing himself in Boston, he devoted himself to the practice of medicine, and finally rose to high professional rank and social position. He became president of the Massachusetts Medical Society, and was employed in editing the vital statistics of the state." In 1848, he was elected as a member of the American Philosophical Society. In 1855 he delivered the annual address at the Massachusetts Medical Society, entitled “Search Out the Secrets of Nature.” He was its president from 1864 until his death. In 1856, he was appointed visiting physician to the Massachusetts General Hospital. Naturalist "As a co ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Margaritifera
''Margaritifera'' is a genus of freshwater mussels, aquatic bivalve molluscs in the family Margaritiferidae, the freshwater pearl mussels. MolluscaBase eds. (2021). MolluscaBase. Margaritifera Schumacher, 1815. Accessed through: World Register of Marine Species at: http://marinespecies.org/aphia.php?p=taxdetails&id=571966 on 2021-06-22 Species Species within the genus ''Margaritifera'' include: * '' Margaritifera auricularia'' or ''Pseudunio auricularia'' * '' Margaritifera falcata'' ( Gould, 1850) * '' Margaritifera hembeli'' (Conrad, 1838) * '' Margaritifera margaritifera'' (Linnaeus, 1758) — Freshwater pearl mussel (includes '' Margaritifera margaritifera durrovensis'' Phillips, 1928) * '' Margaritifera marrianae'' R. I. Johnson, 1983 The following fossil species are known from the mid-Cretaceous of Mongolia, being formerly classified in the genus ''Unio'': * †'' Margaritifera elongata'' (Martinson, 1982) * †'' Margaritifera sainshandensis'' (Martinson, 1982) * †'' ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Oregon Field Guide
''Oregon Field Guide'' is a weekly television program produced by Oregon Public Broadcasting focusing on recreation, the outdoors, and environmental issues in the state of Oregon. The show has become part of the Oregon zeitgeist. Steve Amen is the show's creator and original Executive Producer. Ed Jahn, producer with Oregon Field Guide since 2000, became host and Executive Producer in 2016/2017 upon Steve Amen's retirement. Named for the field guides used to identify plants, animals, and natural phenomenon, the wide-ranging series covers Oregon natural history, outdoor recreation, conservation, agriculture, rural life, and other local subjects. Produced with deep narratives rather than short segments, roughly 13 half-hour episodes and specials are shown per year. History ''Oregon Field Guide'' started as a partnership between Oregon Public Broadcasting (OPB) and the Oregon Department of Fish and Wildlife. The pilot first aired in 1989. The program became the sole production of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glochidia
The glochidium (plural glochidia) is a microscopic larval stage of some freshwater mussels, aquatic bivalve mollusks in the families Unionidae and Margaritiferidae, the river mussels and European freshwater pearl mussels. These larvae are tiny and are typically between 100 and 200 micrometers, or approximately a third of the size of a grain of salt. They can be round or have hooks, attaching to the gills, fins and scales of fish (for example to the gills of a fish host species) for a period before it detaches and falls to the substrate and takes on the typical form of a juvenile mussel. Since a fish is active and free-swimming, this process helps distribute the mussel species to potential areas of habitat that it could not reach any other way. Before the origin of this larval form was understood, it was described as "parasitic worms" on the fish host, although under normal circumstances, glochidia do not harm fish. Overexposure or heavy infections of glochidia may however g ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pleistocene
The Pleistocene ( , often referred to as the '' Ice age'') is the geological epoch that lasted from about 2,580,000 to 11,700 years ago, spanning the Earth's most recent period of repeated glaciations. Before a change was finally confirmed in 2009 by the International Union of Geological Sciences, the cutoff of the Pleistocene and the preceding Pliocene was regarded as being 1.806 million years Before Present (BP). Publications from earlier years may use either definition of the period. The end of the Pleistocene corresponds with the end of the last glacial period and also with the end of the Paleolithic age used in archaeology. The name is a combination of Ancient Greek grc, label=none, πλεῖστος, pleīstos, most and grc, label=none, καινός, kainós (latinized as ), 'new'. At the end of the preceding Pliocene, the previously isolated North and South American continents were joined by the Isthmus of Panama, causing a faunal interchange between the t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Westslope Cutthroat Trout
The westslope cutthroat trout (''Oncorhynchus clarkii lewisi''), also known as the black-spotted trout, common cutthroat trout and red-throated trout is a subspecies of the cutthroat trout (''Oncorhynchus clarkii'') and is a freshwater fish in the salmon family (biology), family (family Salmonidae) of order (biology), order Salmoniformes. The cutthroat is the Montana state fish.1-1-507. State fish Montana Code, accessed 23 April 2009. This subspecies is a ''species of concern'' in its Montana and British Columbia ranges and is considered ''threatened'' in its native range in Alberta. Taxonomy The scientific name of the westslope cutthroat trout is ''Oncorhynchus clarkii lewisi''. The subspecies was first described in the journals of explorer William Clark from specimens obtained during the Lewis and Clark E ...[...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Glacial Advance
Glacial motion is the motion of glaciers, which can be likened to rivers of ice. It has played an important role in sculpting many landscapes. Most lakes in the world occupy basins scoured out by glaciers. Glacial motion can be fast (up to , observed on Jakobshavn Isbræ in Greenland) or slow ( on small glaciers or in the center of ice sheets), but is typically around . Processes of motion Glacier motion occurs from four processes, all driven by gravity: basal sliding, glacial quakes generating fractional movements of large sections of ice, bed deformation, and internal deformation. * In the case of basal sliding, the entire glacier slides over its bed. This type of motion is enhanced if the bed is soft sediment, if the glacier bed is thawed and if meltwater is prevalent. * Bed deformation is thus usually limited to areas of sliding. Seasonal melt ponding and penetrating under glaciers shows seasonal acceleration and deceleration of ice flows affecting whole icesheets. * ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Drainage Basin
A drainage basin is an area of land where all flowing surface water converges to a single point, such as a river mouth, or flows into another body of water, such as a lake or ocean. A basin is separated from adjacent basins by a perimeter, the ''drainage divide'', made up of a succession of elevated features, such as ridges and hills. A basin may consist of smaller basins that merge at river confluences, forming a hierarchical pattern. Other terms for a drainage basin are catchment area, catchment basin, drainage area, river basin, water basin, and impluvium. In North America, they are commonly called a watershed, though in other English-speaking places, "watershed" is used only in its original sense, that of a drainage divide. In a closed drainage basin, or endorheic basin, the water converges to a single point inside the basin, known as a sink, which may be a permanent lake, a dry lake, or a point where surface water is lost underground. Drainage basins are similar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Headwater Capture
The headwaters of a river or stream is the farthest place in that river or stream from its estuary or downstream confluence with another river, as measured along the course of the river. It is also known as a river's source. Definition The United States Geological Survey (USGS) states that a river's "length may be considered to be the distance from the mouth to the most distant headwater source (irrespective of stream name), or from the mouth to the headwaters of the stream commonly known as the source stream". As an example of the second definition above, the USGS at times considers the Missouri River as a tributary of the Mississippi River. But it also follows the first definition above (along with virtually all other geographic authorities and publications) in using the combined Missouri—lower Mississippi length figure in lists of lengths of rivers around the world. Most rivers have numerous tributaries and change names often; it is customary to regard the longe ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Margaritifera Margaritifera
The freshwater pearl mussel (''Margaritifera margaritifera'') is an endangered species of freshwater mussel, an aquatic bivalve mollusc in the family Margaritiferidae. Although the name "freshwater pearl mussel" is often used for this species, other freshwater mussel species (e.g. '' Margaritifera auricularia'') can also create pearls and some can also be used as a source of mother of pearl. Most cultured pearls today come from ''Hyriopsis'' species in Asia, or ''Amblema'' species in North America, both members of the related family Unionidae; pearls are also found within species in the genus ''Unio''. The interior of the shell of ''Margaritifera margaritifera'' has thick nacre (the inner mother of pearl layer of the shell). This species is capable of making fine-quality pearls, and was historically exploited in the search for pearls from wild sources. In recent times, the Russian malacologist Valeriy Zyuganov received worldwide reputation after he discovered that the pearl ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Headwaters
The headwaters of a river or stream is the farthest place in that river or stream from its estuary or downstream confluence with another river, as measured along the course of the river. It is also known as a river's source. Definition The United States Geological Survey (USGS) states that a river's "length may be considered to be the distance from the mouth to the most distant headwater source (irrespective of stream name), or from the mouth to the headwaters of the stream commonly known as the source stream". As an example of the second definition above, the USGS at times considers the Missouri River as a tributary of the Mississippi River. But it also follows the first definition above (along with virtually all other geographic authorities and publications) in using the combined Missouri—lower Mississippi length figure in lists of lengths of rivers around the world. Most rivers have numerous tributaries and change names often; it is customary to regard the longest ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
