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Louisiana Pearlshell
The Louisiana pearlshell, ''Margaritifera hembeli'', is a rare species of bivalve mollusk in the family Margaritiferidae. This freshwater mussel is native to Louisiana in the United States, and was previously present also in Arkansas. It grows to a length of about and lives on the sand or gravel stream-bed in riffles and fast flowing stretches of small streams. Its life cycle involves a stage where it lives parasitically inside a fish. This mollusk is sensitive to increased sedimentation and cannot tolerate impoundments. Because of its limited range and its population decline, the International Union for Conservation of Nature has rated this mollusk as being " critically endangered". Description This mussel reaches about 10 centimeters long by 5 wide and 3 high. It is dark brown or black in color with a white nacre.USFWSFinal endangered status for Louisiana Pearlshell (''Margaritifera hembeli'').''Federal Register'' February 5, 1988. Ecology This mussel lives in small, shallo ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Timothy Abbott Conrad
Timothy Abbott Conrad (June 21, 1803 in Trenton, New Jersey – August 9, 1877 in Trenton) was an American geologist and malacologist. Biography He was from early life an investigator of American paleontology and natural history, devoting himself to the study of the shells of the Tertiary and Cretaceous formations, and to existing species of mollusks. In 1831 he began the issue of a work on “American Marine Conchology,” and the year following published the first number of his “Fossil Shells of the Tertiary Formation,” which was never completed. A “Monography of the Family Unionidae” was issued between 1835 and 1847. The lithographed plates in his publications were in part his own work. He contributed many articles to the '' American Journal of Science'' and the ''Journal of the Philadelphia Academy of Science''. As one of the New York state geologists he prepared the geological report for 1837. He was paleontologist of the New York Geological Survey from 1838 until ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Red River Of The South
The Red River, or sometimes the Red River of the South, is a major river in the Southern United States. It was named for its reddish water color from passing through red-bed country in its watershed. It is one of several rivers with that name. Although once a tributary of the Mississippi River, the Red River is now a tributary of the Atchafalaya River, a distributary of the Mississippi that flows separately into the Gulf of Mexico. This confluence is connected to the Mississippi River by the Old River Control Structure. The south bank of the Red River formed part of the US–Mexico border from the Adams–Onís Treaty (in force 1821) until the Texas Annexation and the Treaty of Guadalupe Hidalgo. The Red River is the second-largest river basin in the southern Great Plains. It rises in two branches in the Texas Panhandle and flows east, where it serves as the border between the states of Texas and Oklahoma. It forms a short border between Texas and Arkansas before entering Ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Margaritifera
''Margaritifera'' is a genus of freshwater mussels, Aquatic animal, 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'' (Augustus Addison Gould, Gould, 1850) * ''Margaritifera hembeli'' (Conrad, 1838) * ''Margaritifera margaritifera'' (Carl Linnaeus, Linnaeus, 10th edition of Systema Naturae, 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 (bivalve), Unio'': * †''Margaritifera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Natural History Of Louisiana
Nature, in the broadest sense, is the physical world or universe. "Nature" can refer to the phenomena of the physical world, and also to life in general. The study of nature is a large, if not the only, part of science. Although humans are part of nature, human activity is often understood as a separate category from other natural phenomena. The word ''nature'' is borrowed from the Old French ''nature'' and is derived from the Latin word ''natura'', or "essential qualities, innate disposition", and in ancient times, literally meant "birth". In ancient philosophy, ''natura'' is mostly used as the Latin translation of the Greek word ''physis'' (φύσις), which originally related to the intrinsic characteristics of plants, animals, and other features of the world to develop of their own accord. The concept of nature as a whole, the physical universe, is one of several expansions of the original notion; it began with certain core applications of the word φύσις by pre-Socr ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetic Variability
Genetic variability is either the presence of, or the generation of, genetic differences. It is defined as "the formation of individuals differing in genotype, or the presence of genotypically different individuals, in contrast to environmentally induced differences which, as a rule, cause only temporary, nonheritable changes of the phenotype". Genetic variability in a population is important for biodiversity. Causes There are many sources of genetic variability in a population: *Homologous recombination is a significant source of variability. During meiosis in sexual organisms, two homologous chromosomes cross over one another and exchange genetic material. The chromosomes then split apart and are ready to contribute to forming an offspring. Recombination is random and is governed by its own set of genes. Being controlled by genes means that recombination is variable in frequency. *Immigration, emigration, and translocation – each of these is the movement of an individual ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Genetic Analysis
Genetic analysis is the overall process of studying and researching in fields of science that involve genetics and molecular biology. There are a number of applications that are developed from this research, and these are also considered parts of the process. The base system of analysis revolves around general genetics. Basic studies include identification of genes and inherited disorders. This research has been conducted for centuries on both a large-scale physical observation basis and on a more microscopic scale. Genetic analysis can be used generally to describe methods both used in and resulting from the sciences of genetics and molecular biology, or to applications resulting from this research. Genetic analysis may be done to identify genetic/inherited disorders and also to make a differential diagnosis in certain somatic diseases such as cancer. Genetic analyses of cancer include detection of mutations, fusion genes, and DNA copy number changes. History of genetic analysi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Livestock
Livestock are the domesticated animals raised in an agricultural setting to provide labor and produce diversified products for consumption such as meat, eggs, milk, fur, leather, and wool. The term is sometimes used to refer solely to animals who are raised for consumption, and sometimes used to refer solely to farmed ruminants, such as cattle, sheep, goats and pigs. Horses are considered livestock in the United States. The USDA classifies pork, veal, beef, and lamb (mutton) as livestock, and all livestock as red meat. Poultry and fish are not included in the category. The breeding, maintenance, slaughter and general subjugation of livestock, called '' animal husbandry'', is a part of modern agriculture and has been practiced in many cultures since humanity's transition to farming from hunter-gatherer lifestyles. Animal husbandry practices have varied widely across cultures and time periods. It continues to play a major economic and cultural role in numerous communities. Lives ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Silviculture
Silviculture is the practice of controlling the growth, composition/structure, and quality of forests to meet values and needs, specifically timber production. The name comes from the Latin ('forest') and ('growing'). The study of forests and woods is termed ''silvology''. Silviculture also focuses on making sure that the treatment(s) of forest stands are used to conserve and improve their productivity. Generally, silviculture is the science and art of growing and cultivating forest crops, based on a knowledge of silvics (the study of the life-history and general characteristics of forest trees and stands, with particular reference to local/regional factors). The focus of silviculture is the control, establishment and management of forest stands. The distinction between forestry and silviculture is that silviculture is applied at the stand-level, while forestry is a broader concept. Adaptive management is common in silviculture, while forestry can include natural/conserved land ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Sediment
Sediment is a naturally occurring material that is broken down by processes of weathering and erosion, and is subsequently transported by the action of wind, water, or ice or by the force of gravity acting on the particles. For example, sand and silt can be carried in suspension in river water and on reaching the sea bed deposited by sedimentation; if buried, they may eventually become sandstone and siltstone (sedimentary rocks) through lithification. Sediments are most often transported by water (fluvial processes), but also wind (aeolian processes) and glaciers. Beach sands and river channel deposits are examples of fluvial transport and deposition, though sediment also often settles out of slow-moving or standing water in lakes and oceans. Desert sand dunes and loess are examples of aeolian transport and deposition. Glacial moraine deposits and till are ice-transported sediments. Classification Sediment can be classified based on its grain size, grain shape, and c ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kisatchie National Forest
Kisatchie National Forest, the only National forest in Louisiana, United States, is located in the forested piney hills and hardwood bottoms of seven central and northern parishes. It is part of the Cenozoic uplands (some of Louisiana's oldest rocks) and has large areas of longleaf pine forests (a forest type that has declined significantly over the last century). It is one of the largest pieces of natural landscape in Louisiana, with some of public land, more than half of which is vital longleaf pine and flatwoods vegetation. These support many rare plant and animal species. There are also rare habitats, such as hillside seepage bogs and calcareous prairies. The forest also contains and provides a buffer for the Kisatchie Hills Wilderness, a nationally designated wilderness area that contributes to protecting biodiversity of the coastal plain region of the United States. The forest was designated in 1930 during the administration of U.S. President Herbert Hoover. Kisatchi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beaver Dam
A beaver dam or beaver impoundment is a dam built by beavers to create a pond which protects against predators such as coyotes, wolves and bears, and holds their food during winter. These structures modify the natural environment in such a way that the overall ecosystem builds upon the change, making beavers a keystone species and ecosystem engineers. They build prolifically at night, carrying mud and stones with their forepaws and timber between their teeth. Construction A minimum water level of is required to keep the underwater entrance to beaver lodges from being blocked by ice during the winter. In lakes, rivers and large streams with deep enough water, beavers may not even need to build dams, and instead simply live in bank burrows and lodges. If the water is not deep enough to keep beavers safe from predators and their lodge entrances ice-free, beavers build dams.Beavers start construction by diverting the stream to lessen the water's flow pressure. Branches and logs ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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