A pearl is a hard, glistening object produced within the soft tissue of a living shelled mollusk or another animal, such as fossil conulariids. Just like the shell of a mollusk, a pearl is composed of calcium carbonate in minute crystalline form, which has deposited in concentric layers. The ideal pearl is perfectly round and smooth, but many other shapes, known as baroque pearls, can occur. The finest quality of natural pearls have been highly valued as gemstones and objects of beauty for many centuries. Because of this, pearl has become a metaphor for something rare, fine, admirable and valuable.
The River Irt is a river in the county of Cumbria in northern England. It flows for approximately 22 kilometres (14 mi) from its source in Wast Water to its estuary at Ravenglass.
The River Ehen is a river in Cumbria, England.
The freshwater pearl mussel is an endangered species of freshwater mussel, an aquatic bivalve mollusc in the family Margaritiferidae.
The Rede is a river in Northumberland, England. The river rises on Carter Fell on the Anglo-Scottish border feeding Catcleugh Reservoir and joins the River North Tyne below the village of Redesmouth. The Rede is one of only two rivers in the North East of England that has the freshwater pearl mussel in its waters.
Margaritiferidae is a family of medium-sized freshwater mussels, aquatic bivalve molluscs in the order Unionida. It is the most threatened of all unionid families.
Cumberlandia monodonta is a freshwater mussel endemic to the United States. Currently, C. monodonta is listed as an endangered species by the U.S. Fish and Wildlife Service and the International Union for Conservation of Nature.
Margaritifera auricularia is a species of European freshwater mussel, an aquatic bivalve mollusk in the family Margaritiferidae, the freshwater pearl mussels. Formerly found throughout western and central Europe, the species is now critically endangered and is one of the rarest invertebrates worldwide, being confined to a few rivers in Spain and France. M. auricularia is commonly known as Spengler's freshwater mussel in honour of Lorenz Spengler, who first described this species.
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 10 cm (4 in) 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".
Margaritifera marrianae, the Alabama pearlshell, is a species of freshwater mussel, an aquatic bivalve mollusk in the family Margaritiferidae, the freshwater pearl mussels.
Freshwater bivalves are molluscs of the order Bivalvia that inhabit freshwater ecosystems. They are one of the two main groups of freshwater molluscs, along with freshwater snails.
The golden pebblesnail, scientific name Somatogyrus aureus, is a species of minute freshwater snails with an operculum, aquatic gastropod molluscs or micromolluscs in the family Lithoglyphidae. This species is endemic to Alabama and Tennessee in the United States. Its natural habitat is the Tennessee River system, with the type locality being given as the Holston River.
The Cladagh River, Claddagh or Swanlinbar River, is a moderately large river which forms from a number of small streams rising in Commas townland on the south-eastern slopes of Cuilcagh Mountain, County Cavan, and flows through the village of Swanlinbar, before crossing the border into County Fermanagh and eventually flowing into Upper Lough Erne. It is ultra-oligotrophic upstream before gradually becoming oligotrophic and oligo-mesotrophic through its middle and lower reaches.
Valeriy Valeryevich Zyuganov (Russian: Зюганов Валерий Валерьевич, born 31 July 1955 in Yangiyo‘l city, is a Soviet and Russian biologist, and Doctor of Biological Sciences. He is the pupil and follower of professors V.V. Khlebovich,the Zoological Institute of the Russian Academy of Sciences and Yu. A. Labas.A.N. Severtsov Institute of Ecology and Evolution of the Russian Academy of SciencesArchived 2007-12-13 at the Wayback Machine
Afon Eden is a tributary river than runs into the Afon Mawddach in Gwynedd, Wales. It is a protected river because it is one of the few breeding grounds for freshwater pearl mussels.
The western pearlshell 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.
The River Allow is a river in Ireland, flowing through County Limerick and County Cork.
Aquaculture in the United Kingdom is dominated by salmon farming, then by mussel production with trout being the third most important enterprise. Aquaculture in the United Kingdom represents a significant business for the UK, producing over 200,000 tonnes of fish whilst earning over £700 million in 2012 (€793 million).
The Nore pearl mussel is a critically endangered species of freshwater pearl mussel, an aquatic bivalve mollusc in the family Margaritiferidae.
