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Astacus Colchicus
''Astacus'' (from the Greek , ', meaning "lobster" or "crayfish") is a genus of crayfish found in Europe and western Asia, comprising three extant (living) species and three extinct fossil species. Due to the crayfish plague, crayfish of this genus have declined in many European regions, being replaced by the invasive North American signal crayfish, which carries the plague but is unaffected by it. Classification ''Astacus'' belongs to the family Astacidae, one of the three families of Northern Hemisphere freshwater crayfish within the superfamily Astacoidea. The internal phylogeny of Astacidae can be shown in the cladogram below: Extant species *''Astacus astacus'' (Linnaeus, 1775) - known as the "European crayfish", "noble crayfish" or "broad-fingered crayfish" - it is distributed across Europe, in France throughout Central Europe, to the Balkan Peninsula, and north as far as parts of the British Isles, Scandinavia, and the western parts of the former Soviet Union. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astacus Astacus
''Astacus astacus'', the European crayfish, noble crayfish, or broad-fingered crayfish, is the most common species of crayfish in Europe, and a traditional food source. Like other true crayfish, ''A. astacus'' is restricted to fresh water, living only in unpolluted streams, rivers, and lakes. It is found from France throughout Central Europe, to the Balkan Peninsula, and north as far as Scandinavia and Finland, and Eastern Europe. Males may grow up to 16 cm long, and females up to 12 cm. Ecology European crayfish feed on worms, aquatic insects, molluscs, and plants. They are nocturnal, spending the day resting in a burrow. They prefer habitats with high levels of shelter availability. The waters they are found in tend to be soft-bottomed with some sand, and they do not tend to be found in muddy water. ''A. astacus'' become sexually mature after three to four years and a series of moults, and breed in October and November. Fertilised eggs are carried by the ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Extinct
Extinction is the termination of a kind of organism or of a group of kinds (taxon), usually a species. The moment of extinction is generally considered to be the death of the last individual of the species, although the capacity to breed and recover may have been lost before this point. Because a species' potential range may be very large, determining this moment is difficult, and is usually done retrospectively. This difficulty leads to phenomena such as Lazarus taxa, where a species presumed extinct abruptly "reappears" (typically in the fossil record) after a period of apparent absence. More than 99% of all species that ever lived on Earth, amounting to over five billion species, are estimated to have died out. It is estimated that there are currently around 8.7 million species of eukaryote globally, and possibly many times more if microorganisms, like bacteria, are included. Notable extinct animal species include non-avian dinosaurs, saber-toothed cats, dodos, m ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Phylogeny
A phylogenetic tree (also phylogeny or evolutionary tree Felsenstein J. (2004). ''Inferring Phylogenies'' Sinauer Associates: Sunderland, MA.) is a branching diagram or a tree showing the evolutionary relationships among various biological species or other entities based upon similarities and differences in their physical or genetic characteristics. All life on Earth is part of a single phylogenetic tree, indicating common ancestry. In a ''rooted'' phylogenetic tree, each node with descendants represents the inferred most recent common ancestor of those descendants, and the edge lengths in some trees may be interpreted as time estimates. Each node is called a taxonomic unit. Internal nodes are generally called hypothetical taxonomic units, as they cannot be directly observed. Trees are useful in fields of biology such as bioinformatics, systematics, and phylogenetics. ''Unrooted'' trees illustrate only the relatedness of the leaf nodes and do not require the ancestral root to be ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astacoidea
Astacoidea is superfamily of freshwater crayfish that live in the Northern Hemisphere. The other superfamily of crayfish, Parastacoidea, lives in the Southern Hemisphere. Astacoidea consists of three families: Astacidae (from Europe and western North America), Cambaridae (from eastern North America), and Cambaroididae (from eastern Asia). Crayfish are closely related to lobsters, as shown in the simplified cladogram A cladogram (from Greek ''clados'' "branch" and ''gramma'' "character") is a diagram used in cladistics to show relations among organisms. A cladogram is not, however, an evolutionary tree because it does not show how ancestors are related to d ... below: References Crayfish Freshwater crustaceans Crustacean taxonomy Arthropod superfamilies Taxa named by Pierre André Latreille {{Decapod-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Superfamily (biology)
In biological classification, taxonomic rank is the relative level of a group of organisms (a taxon) in an ancestral or hereditary hierarchy. A common system consists of species, genus, family, order, class, phylum, kingdom, domain. While older approaches to taxonomic classification were phenomenological, forming groups on the basis of similarities in appearance, organic structure and behaviour, methods based on genetic analysis have opened the road to cladistics. A given rank subsumes under it less general categories, that is, more specific descriptions of life forms. Above it, each rank is classified within more general categories of organisms and groups of organisms related to each other through inheritance of traits or features from common ancestors. The rank of any ''species'' and the description of its ''genus'' is ''basic''; which means that to identify a particular organism, it is usually not necessary to specify ranks other than these first two. Consider a particular ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Northern Hemisphere
The Northern Hemisphere is the half of Earth that is north of the Equator. For other planets in the Solar System, north is defined as being in the same celestial hemisphere relative to the invariable plane of the solar system as Earth's North Pole. Owing to Earth's axial tilt of 23.439281°, winter in the Northern Hemisphere lasts from the December solstice (typically December 21 UTC) to the March equinox (typically March 20 UTC), while summer lasts from the June solstice through to the September equinox (typically on 23 September UTC). The dates vary each year due to the difference between the calendar year and the astronomical year. Within the Northern Hemisphere, oceanic currents can change the weather patterns that affect many factors within the north coast. Such events include El Niño–Southern Oscillation. Trade winds blow from east to west just above the equator. The winds pull surface water with them, creating currents, which flow westward due to the Coriolis e ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astacidae
Astacidae is a family of freshwater crayfish native to Europe and western North America. The family is made up of four extant (living) genera: The genera ''Astacus'' (which includes the European crayfish), ''Pontastacus'' (which includes the Turkish crayfish), and ''Austropotamobius'' are all found throughout Europe and parts of western Asia, while ''Pacifastacus'' is found on the Pacific coast of the United States and British Columbia and includes the signal crayfish and the Shasta crayfish. Classification and Phylogeny Astacidae belongs to the superfamily Astacoidea, which contains all crayfish in the Northern Hemisphere. Astacoidea is the sister taxon to Parastacoidea, which contains all crayfish of the Southern Hemisphere. Crayfish and lobsters together comprise the infraorder Astacidea, as shown in the simplified cladogram below: The internal phylogeny of Astacidae can be further shown in the cladogram below: Species The family Astacidae contains the following genera ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Family (biology)
Family ( la, familia, plural ') is one of the eight major hierarchical taxonomic ranks in Linnaean taxonomy. It is classified between order and genus. A family may be divided into subfamilies, which are intermediate ranks between the ranks of family and genus. The official family names are Latin in origin; however, popular names are often used: for example, walnut trees and hickory trees belong to the family Juglandaceae, but that family is commonly referred to as the "walnut family". What belongs to a family—or if a described family should be recognized at all—are proposed and determined by practicing taxonomists. There are no hard rules for describing or recognizing a family, but in plants, they can be characterized on the basis of both vegetative and reproductive features of plant species. Taxonomists often take different positions about descriptions, and there may be no broad consensus across the scientific community for some time. The publishing of new data and opini ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Astacus Astacus 01
''Astacus'' (from the Greek , ', meaning "lobster" or "crayfish") is a genus of crayfish found in Europe and western Asia, comprising three extant (living) species and three extinct fossil species. Due to the crayfish plague, crayfish of this genus have declined in many European regions, being replaced by the invasive North American signal crayfish, which carries the plague but is unaffected by it. Classification ''Astacus'' belongs to the family Astacidae, one of the three families of Northern Hemisphere freshwater crayfish within the superfamily Astacoidea. The internal phylogeny of Astacidae can be shown in the cladogram below: Extant species *''Astacus astacus'' (Linnaeus, 1775) - known as the "European crayfish", "noble crayfish" or "broad-fingered crayfish" - it is distributed across Europe, in France throughout Central Europe, to the Balkan Peninsula, and north as far as parts of the British Isles, Scandinavia, and the western parts of the former Soviet Union. ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
ARKive
ARKive was a global initiative with the mission of "promoting the conservation of the world's threatened species, through the power of wildlife imagery", which it did by locating and gathering films, photographs and audio recordings of the world's species into a centralised digital archive. Its priority was the completion of audio-visual profiles for the c. 17,000 species on the IUCN Red List of Threatened Species. The project was an initiative of Wildscreen, a UK-registered educational charity, based in Bristol. The technical platform was created by Hewlett-Packard, as part of the HP Labs' Digital Media Systems research programme. ARKive had the backing of leading conservation organisations, including BirdLife International, Conservation International, International Union for Conservation of Nature (IUCN), the United Nations' World Conservation Monitoring Centre (UNEP-WCMC), and the World Wide Fund for Nature (WWF), as well as leading academic and research institutions, such ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Signal Crayfish
The signal crayfish (''Pacifastacus leniusculus'') is a North American species of crayfish. It was introduced to Europe in the 1960s to supplement the North European ''Astacus astacus'' fisheries, which were being damaged by crayfish plague, but the imports turned out to be a carrier of that disease. The signal crayfish is now considered an invasive species across Europe, Japan, and California, ousting native species there. Description and ecology Members of this species are typically long, although sizes up to are possible. They are bluish-brown to reddish-brown in colour, with robust, large, smooth claws. They have a white to pale blue-green patch near the claw hinge, like the white flags that signalmen used for directing trains—hence the name. The lifecycle of the signal crayfish is typical for the family Astacidae. Around 200–400 eggs are laid after mating in the autumn, and are carried under the female's tail until they are ready to hatch the following spring. The ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Invasive Species
An invasive species otherwise known as an alien is an introduced organism that becomes overpopulated and harms its new environment. Although most introduced species are neutral or beneficial with respect to other species, invasive species adversely affect habitats and bioregions, causing ecological, environmental, and/or economic damage. The term can also be used for native species that become harmful to their native environment after human alterations to its food webfor example the purple sea urchin (''Strongylocentrotus purpuratus'') which has decimated kelp forests along the northern California coast due to overharvesting of its natural predator, the California sea otter (''Enhydra lutris''). Since the 20th century, invasive species have become a serious economic, social, and environmental threat. Invasion of long-established ecosystems by organisms is a natural phenomenon, but human-facilitated introductions have greatly increased the rate, scale, and geographic range of ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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