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Gymnocephalus Cernua
The ruffe (''Gymnocephalus cernua''), also known as the Eurasian ruffe or pope, is a freshwater fish found in temperate regions of Europe and northern Asia. It has been introduced into the Great Lakes of North America as an invasive species and is causing unfortunate results as it is reproducing faster than other species. Its common names are ambiguous – "ruffe" may refer to any local member of its genus ''Gymnocephalus'', which as a whole is native to Eurasia. Description The ruffe's colors and markings are similar to those of the walleye, an olive-brown to golden-brown color on its back, paler on the sides with yellowish white undersides. The ruffe can reach up to in length, but is usually around half that size. It is a very aggressive fish for its size. The ruffe also has a large, spiny dorsal fin which is likely distasteful to its predators. It also has two fins on top, the front fin has hard and sharp spines, the back fin has soft spines called rays. The most obvious ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pärnu (river)
The Pärnu () is a river in Estonia. It drains into Pärnu Bay, which is an inlet of the Gulf of Riga. At 144 km, it is one of the longest rivers in Estonia, with a basin area of 6,920 km2 and an average discharge of 64.4 m³/s. Description The Pärnu is the second longest river in Estonia at , and one of only ten rivers in the country which is longer than . Its catchment area is , occupying roughly one-sixth of the landmass of Estonia and one of only 15 catchment areas of Estonian rivers which exceeds . Its sources are in the karst upland of Pandivere, in north-eastern Estonia, and its main tributaries join the river from the upland of Sakala. Due to its length, the river Pärnu passes through most of the landscape types found in Estonia. The rivers' surroundings are dominated by agriculture and its upper reaches in Järva County is considered some of the best arable land in Estonia. In the area around Paide town, the river flows through forests and wetlands. It disch ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Black Sea
The Black Sea is a marginal sea, marginal Mediterranean sea (oceanography), mediterranean sea lying between Europe and Asia, east of the Balkans, south of the East European Plain, west of the Caucasus, and north of Anatolia. It is bounded by Bulgaria, Georgia (country), Georgia, Romania, Russia, Turkey, and Ukraine. The Black Sea is Inflow (hydrology), supplied by major rivers, principally the Danube, Dnieper and Dniester. Consequently, while six countries have a coastline on the sea, its drainage basin includes parts of 24 countries in Europe. The Black Sea, not including the Sea of Azov, covers , has a maximum depth of , and a volume of . Most of its coasts ascend rapidly. These rises are the Pontic Mountains to the south, bar the southwest-facing peninsulas, the Caucasus Mountains to the east, and the Crimean Mountains to the mid-north. In the west, the coast is generally small floodplains below foothills such as the Strandzha; Cape Emine, a dwindling of the east end ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Embryos
An embryo ( ) is the initial stage of development for a multicellular organism. In organisms that reproduce sexually, embryonic development is the part of the life cycle that begins just after fertilization of the female egg cell by the male sperm cell. The resulting fusion of these two cells produces a single-celled zygote that undergoes many cell divisions that produce cells known as blastomeres. The blastomeres (4-cell stage) are arranged as a solid ball that when reaching a certain size, called a morula, (16-cell stage) takes in fluid to create a cavity called a blastocoel. The structure is then termed a blastula, or a blastocyst in mammals. The mammalian blastocyst hatches before implantating into the endometrial lining of the womb. Once implanted the embryo will continue its development through the next stages of gastrulation, neurulation, and organogenesis. Gastrulation is the formation of the three germ layers that will form all of the different parts of the body. Ne ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Diameter
In geometry, a diameter of a circle is any straight line segment that passes through the centre of the circle and whose endpoints lie on the circle. It can also be defined as the longest Chord (geometry), chord of the circle. Both definitions are also valid for the diameter of a sphere. In more modern usage, the length d of a diameter is also called the diameter. In this sense one speaks of diameter rather than diameter (which refers to the line segment itself), because all diameters of a circle or sphere have the same length, this being twice the radius r. :d = 2r \qquad\text\qquad r = \frac. The word "diameter" is derived from (), "diameter of a circle", from (), "across, through" and (), "measure". It is often abbreviated \text, \text, d, or \varnothing. Constructions With straightedge and compass, a diameter of a given circle can be constructed as the perpendicular bisector of an arbitrary chord. Drawing two diameters in this way can be used to locate the center of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Spawn (biology)
Spawn is the eggs and sperm released or deposited into water by aquatic animals. As a verb, ''to spawn'' refers to the process of freely releasing eggs and sperm into a body of water (fresh or marine); the physical act is known as spawning. The vast majority of aquatic and amphibious animals reproduce through spawning. These include the following groups: * Bony fishes * Crustaceans (such as crabs, shrimps, etc.) *Mollusks (such as oysters, octopus, squid) *Echinoderms (such as sea urchins, sea stars, sea cucumbers, etc.) * Amphibians (such as frogs, toads, salamanders, newts) * Aquatic insects (such as dragonflies, mayflies, mosquitoes) *Coral, which are living colonies of tiny, aquatic organisms—not plants, as they are sometimes perceived to be. Corals, while appearing sedentary or botanical by nature, actually spawn by releasing clouds of sperm and egg cells into the water column, where the two mix. As a general rule, aquatic or semiaquatic reptiles, birds, ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Benthic Zone
The benthic zone is the ecological region at the lowest level of a body of water such as an ocean, lake, or stream, including the sediment surface and some sub-surface layers. The name comes from the Ancient Greek word (), meaning "the depths". Organisms living in this zone are called benthos and include microorganisms (e.g., bacteria and Fungus, fungi) as well as larger invertebrates, such as crustaceans and polychaetes. Organisms here, known as bottom dwellers, generally live in close relationship with the substrate and many are permanently attached to the bottom. The benthic boundary layer, which includes the bottom layer of water and the uppermost layer of sediment directly influenced by the overlying water, is an integral part of the benthic zone, as it greatly influences the biological activity that takes place there. Examples of contact soil layers include sand bottoms, rocky outcrops, coral, and bay mud. Description Oceans The benthic region of the ocean begins at t ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Journal Of Fish Biology
The ''Journal of Fish Biology'' covers all aspects of fish and fisheries biological research, both freshwater and marine. It is published by Wiley-Blackwell Wiley-Blackwell is an international scientific, technical, medical, and scholarly publishing business of John Wiley & Sons. It was formed by the merger of John Wiley & Sons Global Scientific, Technical, and Medical business with Blackwell Publish ... and is the official journal of the Fisheries Society of the British Isles. External links * Homepage of The Fisheries Society of the British Isles Ichthyology journals Academic journals established in 1969 Monthly journals English-language journals Wiley-Blackwell academic journals {{zoo-journal-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Chironomid
Chironomidae , commonly known as non-biting midges or chironomids , are a family of Nematoceran flies with a global distribution. They are closely related to the families Ceratopogonidae, Simuliidae, and Thaumaleidae. Although many chironomid species superficially resemble mosquitoes, they can be distinguished by the absence of wing scales and elongated mouthparts characteristic of the Culicidae (true mosquitoes). The name Chironomidae stems from the Ancient Greek word ''kheironómos'', "a pantomimist". Common names and biodiversity This is a large taxon of insects. Some estimates of the species numbers suggest well over 10,000 world-wide. Males are easily recognized by their plumose antennae. Adults are known by a variety of vague and inconsistent common names, largely by confusion with other insects. For example, chironomids are known as "lake flies" in parts of Canada and Lake Winnebago, Wisconsin, but "bay flies" in the areas near the bay of Green Bay, Wisconsin. They ar ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Great Lakes
The Great Lakes, also called the Great Lakes of North America, are a series of large interconnected freshwater lakes spanning the Canada–United States border. The five lakes are Lake Superior, Superior, Lake Michigan, Michigan, Lake Huron, Huron, Lake Erie, Erie, and Lake Ontario, Ontario (though hydrologically, Lake Michigan–Huron, Michigan and Huron are a single body of water, joined at the Straits of Mackinac). The Great Lakes Waterway enables modern travel and shipping by water among the lakes. The lakes connect to the Atlantic Ocean via the Saint Lawrence River, and to the Mississippi River basin through the Illinois Waterway. The Great Lakes are the largest group of freshwater lakes on Earth by total area and the second-largest by total volume. They contain 21% of the world's surface fresh water by volume. The total surface is , and the total volume (measured at the low water datum) is , slightly less than the volume of Lake Baikal (, 22–23% of the world's surface f ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Kolyma
Kolyma (, ) or Kolyma Krai () is a historical region in the Russian Far East that includes the basin of Kolyma River and the northern shores of the Sea of Okhotsk, as well as the Kolyma Mountains (the watershed of the two). It is bounded to the north by the East Siberian Sea and the Arctic Ocean, and by the Sea of Okhotsk to the south. Kolyma Krai was never formally defined and over time it was split among various administrative units. , it consists roughly of the Magadan Oblast, north-eastern areas of Sakha Republic, Yakutia, and the Bilibinsky District of Chukotka Autonomous Okrug. The area, part of which is within the Arctic Circle, has a subarctic climate with very cold winters lasting up to six months of the year. Permafrost and tundra cover a large part of the region. Average winter temperatures range from (even lower in the interior), and average summer temperatures, from . There are rich reserves of gold, silver, tin, tungsten, mercury (element), mercury, copper, a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scandinavia
Scandinavia is a subregion#Europe, subregion of northern Europe, with strong historical, cultural, and linguistic ties between its constituent peoples. ''Scandinavia'' most commonly refers to Denmark, Norway, and Sweden. It can sometimes also refer to the Scandinavian Peninsula (which excludes Denmark but includes a part of northern Finland). In English usage, Scandinavia is sometimes used as a synonym for Nordic countries. Iceland and the Faroe Islands are sometimes included in Scandinavia for their Ethnolinguistics, ethnolinguistic relations with Sweden, Norway and Denmark. While Finland differs from other Nordic countries in this respect, some authors call it Scandinavian due to its economic and cultural similarities. The geography of the region is varied, from the Norwegian fjords in the west and Scandinavian mountains covering parts of Norway and Sweden, to the low and flat areas of Denmark in the south, as well as archipelagos and lakes in the east. Most of the population ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Great Britain
Great Britain is an island in the North Atlantic Ocean off the north-west coast of continental Europe, consisting of the countries England, Scotland, and Wales. With an area of , it is the largest of the British Isles, the List of European islands by area, largest European island, and the List of islands by area, ninth-largest island in the world. It is dominated by a maritime climate with narrow temperature differences between seasons. The island of Ireland, with an area 40 per cent that of Great Britain, is to the west – these islands, along with over List of islands of the British Isles, 1,000 smaller surrounding islands and named substantial rocks, comprise the British Isles archipelago. Connected to mainland Europe until 9,000 years ago by a land bridge now known as Doggerland, Great Britain has been inhabited by modern humans for around 30,000 years. In 2011, it had a population of about , making it the world's List of islands by population, third-most-populous islan ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
