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Sturgeons
Sturgeon is the common name for the 27 species of fish belonging to the family Acipenseridae. The earliest sturgeon fossils date to the Late Cretaceous, and are descended from other, earlier acipenseriform fish, which date back to the Early Jurassic period, some 174 to 201 million years ago. They are one of two living families of the Acipenseriformes alongside paddlefish (Polyodontidae). The family is grouped into four genera: ''Acipenser'' (which is paraphyletic, containing many distantly related sturgeon species), ''Huso'', ''Scaphirhynchus,'' and ''Pseudoscaphirhynchus''. Two species ('' A. naccarii'' and '' A. dabryanus'') may be extinct in the wild, and one ('' P. fedtschenkoi'') may be entirely extinct. Sturgeons are native to subtropical, temperate and sub-Arctic rivers, lakes and coastlines of Eurasia and North America. Sturgeons are long-lived, late-maturing fishes with distinctive characteristics, such as a heterocercal caudal fin similar to those of sharks, and an ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Adriatic Sturgeon
The Adriatic sturgeon (''Acipenser naccarii'') is a species of fish in the family Acipenseridae. It is native to the Adriatic Sea and large rivers which flow in it of Albania, Greece, Italy, Montenegro, Croatia, Bosnia and Herzegovina and Slovenia. Specimens can be seen in several public aquarium, such the Milan Aquarium, Aquarium Finisterrae, Aquarium of the Po, and Oasis of Sant'Alessio in Lombardy. Description The Adriatic sturgeon reaches a maximum length exceeding ; the published maximum weight was 25 kg (55 lb), but large wild fish recently caught were evidently exceeding . Like other sturgeons it has an elongated body, heterocercal tail, partially cartilaginous skeleton, naked skin and longitudinal series of bony scutes on the body. The rostrum is tendentially conical and rather short (1/3 of the head), the head is broad and rounded at the apex, with a protractile mouth which lower lip is thin with a central cleft, and four barbels (circular section) which a ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Beluga (sturgeon)
The beluga (), also known as the beluga sturgeon or great sturgeon (''Huso huso''), is a species of anadromous fish in the sturgeon family ( Acipenseridae) of order Acipenseriformes. It is found primarily in the Caspian and Black Sea basins, and formerly in the Adriatic Sea. Based on maximum size, it is the third-most-massive living species of bony fish.Huso huso. Fishbase.org. Accessed on 11 January 2008 Heavily fished for the female's valuable , known as , wild populations have been greatly reduced by [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Pseudoscaphirhynchus
''Pseudoscaphirhynchus'' is a genus of relatively small, highly threatened sturgeons that are restricted to the Aral Sea system (although extirpated from the Aral Sea itself), including the Amu Darya and Syr Darya river basins, in Central Asia. '' P. fedtschenkoi'' is restricted to Syr Darya, but has not been seen in decades and it is possibly extinct.Mitrofanov, I.V.; and N.Sh. Mamilov (2015). Fish diversity and fisheries in the Caspian Sea and Aral–Syr Darya basin in the Republic of Kazakhstan at the beginning of the 21st Century. Aquatic Ecosystem Health & Management 18(2): 160–170. The two other species in the genus are restricted to Amu Darya: '' P. hermanni'' survives in very low numbers and '' P. kaufmanni'' in low numbers, with both being rated as Critically Endangered by the IUCN.Salnikov, V.B.; V.J. Birstein; and R.L. Mayden (1996). The contemporary status of the two Amu Darya River shovelnose sturgeons, Pseudoscaphirhynchus kaufmanni and P. hermanni. The Sturgeon ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Paddlefish
Paddlefish (family Polyodontidae) are a family of ray-finned fish belonging to order Acipenseriformes, and one of two living groups of the order alongside sturgeons (Acipenseridae). They are distinguished from other fish by their titular elonglated rostrums, which are thought to enhance electroreception to detect prey. Paddlefish have been referred to as "primitive fish" because Acipenseriformes are amongst the earliest diverging lineages of ray-finned fish, having diverged from all other living groups over 300 million years ago. Paddlefish are almost exclusively North American and Chinese, both extant and in the fossil record. There are six known species: four extinct species known only from fossil remains (three from western North America, one from China), one extant species, the American paddlefish (''Polyodon spathula'') which is native to the Mississippi River basin in the U.S., and the Chinese paddlefish (''Psephurus gladius''), declared extinct in 2022 following a 2019 ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acipenseriformes
Acipenseriformes is an order of basal ray-finned fishes that includes living and fossil sturgeons and paddlefishes (Acipenseroidei), as well as the extinct families Chondrosteidae and Peipiaosteidae. They are the second earliest diverging group of living ray-finned fish after the bichirs. Despite being early diverging, they are highly derived, having only weakly ossified skeletons that are mostly made of cartilage, and in modern representatives highly modified skulls. Description The axial skeleton of Acipenseriformes is only partially ossified, with the majority of the bones being replaced with cartilage. The notochord, usually only found in fish embryos, is unconstricted and retained throughout life. The premaxilla and maxilla bones of the skull present in other vertebrates have been lost. The infraorbital nerve is carried by a series of separate canals, rather than being within the circumorbital bones. The palatoquadrate bones of the skull possess a cartilagi ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Atlantic Sturgeon
The Atlantic sturgeon (''Acipenser oxyrinchus oxyrinchus'') is a member of the family Acipenseridae and along with other sturgeon it is sometimes considered a living fossil. The Atlantic sturgeon is one of two subspecies of '' A. oxyrinchus'', the other being the Gulf sturgeon (''A. o. desotoi''). The main range of the Atlantic sturgeon is in eastern North America, extending from New Brunswick, Canada, to the eastern coast of Florida, United States. A disjunct population occurs in the Baltic region of Europe (today only through a reintroduction project). The Atlantic sturgeon was in great abundance when the first European settlers came to North America, but has since declined due to overfishing, water pollution, and habitat impediments such as dams. It is considered threatened, endangered, and even locally extinct in many of its original habitats. The fish can reach 60 years of age, in length and over in weight. Physical appearance Rather than having true scales, the Atlant ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Acipenser
''Acipenser'' is a genus of sturgeons. With 17 living species (others are only known from fossil remains), it is the largest genus in the order Acipenseriformes. The genus is paraphyletic, containing all sturgeons that do not belong to ''Huso'', ''Scaphirhynchus,'' or ''Pseudoscaphirhynchus,'' with many species more closely related to the other three genera than they are to other species of ''Acipenser''. They are native to freshwater and estuarine systems of Eurasia and North America, and most species are threatened. Several species also known to enter near-shore marine environments in the Atlantic, Arctic and Pacific oceans. Living species There are 17 living species: *''Acipenser baerii'' J. F. Brandt, 1869 **'' Acipenser baerii baerii'' J. F. Brandt, 1869 (Siberian sturgeon) **'' Acipenser baerii baicalensis'' A. M. Nikolskii, 1896 (Baikal sturgeon) **''Acipenser baerii stenorrhynchus'' A. M. Nikolskii, 1896 *'' Acipenser brevirostrum'' Lesueur, 1818 (Shortnose sturgeon) ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Huso
''Huso'' is a genus of large sturgeons from Eurasia. It contains two species, both of which are critically endangered: *''Huso dauricus'' (Georgi, 1775) (kaluga) *''Huso huso'' (Linnaeus, 1758) (beluga) Recent data indicate a polyphyletic origin of the genus ''Huso'', and it is suggested that the two ''Huso'' species should be included in the genus ''Acipenser ''Acipenser'' is a genus of sturgeons. With 17 living species (others are only known from fossil remains), it is the largest genus in the order Acipenseriformes. The genus is paraphyletic, containing all sturgeons that do not belong to ''Huso'', ' ...''. References Sturgeons Extant Zanclean first appearances Ray-finned fish genera {{Acipenseriformes-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Scaphirhynchus
''Scaphirhynchus'' is a genus of sturgeons native to the United States of America. All species in this genus are considered to be threatened. The pallid sturgeon is Endangered and the Alabama sturgeon is Critically Endangered. Distribution Member species are found in the Mississippi, Missouri, and Alabama Rivers. Species Currently, three species in this genus are recognized: * '' Scaphirhynchus albus'' ( S. A. Forbes & R. E. Richardson, 1905) (pallid sturgeon) * '' Scaphirhynchus platorynchus'' (Rafinesque, 1820) (shovelnose sturgeon) * '' Scaphirhynchus suttkusi'' J. D. Williams J.D. Williams (born May 22, 1978) is an American actor known for his starring roles in the HBO television programs '' Oz'' as Kenny Wangler, ''The Wire'' as Bodie Broadus and ''Pootie Tang'' as Froggy, ''Surviving Family'' (2012) as Bobby, ''T ... & Clemmer, 1991 (Alabama sturgeon) References Ray-finned fish genera {{Acipenseriformes-stub ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Fish Fin
Fins are distinctive anatomical features composed of bony spines or rays protruding from the body of a fish. They are covered with skin and joined together either in a webbed fashion, as seen in most bony fish, or similar to a flipper, as seen in sharks. Apart from the tail or caudal fin, fish fins have no direct connection with the spine and are supported only by muscles. Their principal function is to help the fish swim. Fins located in different places on the fish serve different purposes such as moving forward, turning, keeping an upright position or stopping. Most fish use fins when swimming, flying fish use pectoral fins for gliding, and frogfish use them for crawling. Fins can also be used for other purposes; male sharks and mosquitofish use a modified fin to deliver sperm, thresher sharks use their caudal fin to stun prey, reef stonefish have spines in their dorsal fins that inject venom, anglerfish use the first spine of their dorsal fin like a fishing rod to lur ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
Estuaries
An estuary is a partially enclosed coastal body of brackish water with one or more rivers or streams flowing into it, and with a free connection to the open sea. Estuaries form a transition zone between river environments and maritime environments and are an example of an ecotone. Estuaries are subject both to marine influences such as tides, waves, and the influx of saline water, and to fluvial influences such as flows of freshwater and sediment. The mixing of seawater and freshwater provides high levels of nutrients both in the water column and in sediment, making estuaries among the most productive natural habitats in the world. Most existing estuaries formed during the Holocene epoch with the flooding of river-eroded or glacially scoured valleys when the sea level began to rise about 10,000–12,000 years ago. Estuaries are typically classified according to their geomorphological features or to water-circulation patterns. They can have many different names, such as bays, har ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
River Delta
A river delta is a landform shaped like a triangle, created by deposition (geology), deposition of sediment that is carried by a river and enters slower-moving or stagnant water. This occurs where a river enters an ocean, sea, estuary, lake, reservoir, or (more rarely) another river that cannot carry away the supplied sediment. It is so named because its triangle shape resembles the Greek letter Delta. The size and shape of a delta is controlled by the balance between watershed processes that supply sediment, and receiving basin processes that redistribute, sequester, and export that sediment. The size, geometry, and location of the receiving basin also plays an important role in delta evolution. River deltas are important in human civilization, as they are major agricultural production centers and population centers. They can provide Coast, coastline defense and can impact drinking water supply. They are also Ecology, ecologically important, with different species' assemblages ... [...More Info...] [...Related Items...] OR: [Wikipedia] [Google] [Baidu] |
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