Notable characteristics of Acipenseriformes include:
Temporal range: Early Triassic–Recent
|Atlantic sturgeon, Acipenser oxyrinchus oxyrinchus|
L. S. Berg, 1940
Acipenser is a genus of sturgeons. With 17 living species (3 others are only known from fossil remains), it is the largest genus in the order Acipenseriformes. They are native to Europe, Asia and North America, and most species are threatened.Acipenseroidei
Acipenseroidei is a suborder of Acipenseriformes animals that contains:
PsephuriniThese animals are well known for the production of caviar.Actinopterygii
Actinopterygii (), or the ray-finned fishes, constitute a class or subclass of the bony fishes.The ray-finned fishes are so called because their fins are webs of skin supported by bony or horny spines ("rays"), as opposed to the fleshy, lobed fins that characterize the class Sarcopterygii (lobe-finned fish). These actinopterygian fin rays attach directly to the proximal or basal skeletal elements, the radials, which represent the link or connection between these fins and the internal skeleton (e.g., pelvic and pectoral girdles).
Numerically, actinopterygians are the dominant class of vertebrates, comprising nearly 99% of the over 30,000 species of fish. They are ubiquitous throughout freshwater and marine environments from the deep sea to the highest mountain streams. Extant species can range in size from Paedocypris, at 8 mm (0.3 in), to the massive ocean sunfish, at 2,300 kg (5,070 lb), and the long-bodied oarfish, at 11 m (36 ft).Beluga (sturgeon)
The beluga or European 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 occasionally in the Adriatic Sea. Heavily fished for the female's valuable roe—known as beluga caviar—the beluga is a huge and late-maturing fish that can live for about 118 years. Going on maximum size, it is the second most massive living species of bony fish behind the ocean sunfish. The species' numbers have been greatly reduced by overfishing and poaching, prompting many governments to enact restrictions on its trade.
The common name for the sturgeon, as for the unrelated beluga whale, is derived from the Russian word белый (belyy), meaning "white", probably referring to the extensive pale colour on the underside in beluga compared to other sturgeons.Chinese sturgeon
The Chinese sturgeon (Acipenser sinensis; Chinese: 中華鱘; pinyin: zhōnghuá xún) is a critically endangered member of the family Acipenseridae in the order Acipenseriformes. Historically, this anadromous fish was found in China, Japan, and the Korean Peninsula, but it has been extirpated from most regions due to habitat loss and overfishing.It is strictly protected by the Chinese government, named a "national treasure" much like its mammalian counterpart, the giant panda. China has several conservation programmes, including reserves specifically aimed at this species and restocking through release of juveniles in the Yangtze River.Chondrostei
Chondrostei are primarily cartilaginous fish showing some degree of ossification. It is thought that the cartilaginous condition is derived, and that the ancestors of this group were bony fish with fully ossified skeletons. Members of this group share with the Elasmobranchii certain features such as the possession of spiracles, a heterocercal tail and the absence of scales. Nevertheless, the fossil record suggests they have more in common with the teleosts. The Chondrostei is probably a paraphyletic grouping; the fifty-two living species are divided among two orders, the Acipenseriformes (sturgeons and paddlefishes), and the Polypteriformes (reedfishes and bichirs).Chondrosteidae
Chondrosteidae is a family of extinct actinopterygian fishes in the order Acipenseriformes.Chondrosteus
Chondrosteus is a genus of extinct actinopterygian (ray-finned fish) belonging to the family Chondrosteidae.Huso
Huso is a genus of large sturgeons from Eurasia. It contains two species, which both 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.Paddlefish
Paddlefish (family Polyodontidae) are basal Chondrostean ray-finned fish. They have been referred to as "primitive fish" because they have evolved with few morphological changes since the earliest fossil records of the Late Cretaceous, seventy to seventy-five million years ago. Polyodontids are exclusively North American and Chinese.There are six known species: four extinct species known only from fossil remains (three from western North America, one from China), and two extant species, including the American paddlefish (Polyodon spathula) which is native to the Mississippi River basin in the U.S. and the critically endangered Chinese paddlefish (Psephurus glades) which is endemic to the Yangtze River Basin in China. Chinese paddlefish are also commonly referred to as "Chinese swordfish", or "elephant fish".Paddlefish populations have declined dramatically throughout their historic range as a result of overfishing, pollution, and the encroachment of human development, including the construction of dams that have blocked their seasonal upward migration to ancestral spawning grounds. Other detrimental effects include alterations of rivers which have changed natural flows resulting in the loss of spawning habitat and nursery areas. Chinese paddlefish have not been seen since 2007, and may now be extinct for many of the same reasons that have plagued the American species.Paleopsephurus
Paleopsephurus is an extinct genus of paddlefish in the Acipenseriformes family Polyodontidae. At present the genus contains the single species Paleopsephurus wilsoni.
The genus is known primarily from the Late Cretaceous, Turonian to the Maastrichtian stage, Hell Creek Formation deposits. Paleopsephurus is one of only two known paddlefish genera to have been found in the North American fossil record, with the genus and species Crossopholis magnicaudatus only being described and found in the Early Eocene Green River Formation. A third extinct genus Protopsephurus with the single species Protopsephurus liui was described from China in 1994. Only two modern paddle fish species are known, Polyodon spathula in the Mississippi River System of North America, and the possibly extinct Psephurus gladius in the Yangtze River of China.Peipiaosteus
Peipiaosteus is an extinct genus of prehistoric ray-finned fish, closely related to living sturgeon and paddlefish. Its fossils are found in the Early Cretaceous Jiufotang Formation, Pani Lake, Liaoning Province, China.Protopsephurus
Protopsephurus is an extinct genus of paddlefish which existed in China during the Barremian age to the Aptian age of the Early Cretaceous period. It contains the species Protopsephurus liui, which was measured to be up to be one meter in length.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.Spiral valve
A spiral valve or scroll valve is the corkscrew-shaped lower portion of the intestine of some sharks, Acipenseriformes (sturgeon and paddlefish), rays, skates, bichirs, and lungfishes. A modification of the ileum, the spiral valve is internally twisted or coiled to increase the surface area of the intestine, to increase nutrient absorption.Strongylosteus
Strongylosteus hindenburgi is an extinct genus of prehistoric bony fish that lived during the early Toarcian stage of the Early Jurassic epoch.Sturgeon
Sturgeon is the common name for the 27 species of fish belonging to the family Acipenseridae. Their evolution dates back to the Triassic some 245 to 208 million years ago. The family is grouped into four genera: Acipenser, Huso, Scaphirhynchus and Pseudoscaphirhynchus. Four species may now be extinct. Two closely related species, Polyodon spathula (American paddlefish) and Psephurus gladius (Chinese paddlefish, possibly extinct) are of the same order, Acipenseriformes, but are in the family Polyodontidae and are not considered to be "true" sturgeons. Both sturgeons and paddlefish have been referred to as "primitive fishes" because their morphological characteristics have remained relatively unchanged since the earliest fossil record. 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 that of sharks, and an elongated spindle-like body that is smooth-skinned, scaleless and armored with 5 lateral rows of bony plates called scutes. Several species can grow quite large, typically ranging 7–12 feet (2-3½ m) in length. The largest sturgeon on record was a Beluga female captured in the Volga estuary in 1827, weighing 1,571 kg (3,463 lb) and 7.2 m (24 ft) long. Most sturgeons are anadromous bottom-feeders which migrate upstream to spawn but spend most of their lives feeding in river deltas and estuaries. Some species inhabit freshwater environments exclusively while others primarily inhabit marine environments near coastal areas, and are known to venture into open ocean.
Several species of sturgeon are harvested for their roe which is processed into caviar—a luxury food and the reason why caviar-producing sturgeons are among the most valuable of all wildlife resources. They are particularly vulnerable to overexploitation and other threats, including pollution and habitat fragmentation. Most species of sturgeon are considered to be at risk of extinction, making them more critically endangered than any other group of species.In art, a sturgeon is the symbol on the coat of arms for Saint Amalberga of Temse.White sturgeon
White sturgeon (Acipenser transmontanus) is a species of sturgeon in the family Acipenseridae of the order Acipenseriformes. They are an anadromous fish species ranging in the Eastern Pacific; from the Gulf of Alaska to Monterey, California. However, some are landlocked in the Columbia River Drainage, Montana, and Lake Shasta in California, with reported sightings in northern Baja California, Mexico.