Acipenseriformes
Quick Summary
The order Acipenseriformes includes primitive ray-finned bony fishes known as chondrosteans. These fish inhabit marine and freshwater environments in the Northern Hemisphere. The only living representatives are sturgeons (family Acipenseridae) and paddlefishes (family Polyodontidae).1
Sturgeons are characterized by bony plates covering their head and body, a heterocercal tail fin, and a toothless, subterminal mouth preceded by barbels used to find food on the bottom. They can grow quite large, with some species reaching lengths of over 8 meters (26.2 feet) and weighing several tons. Paddlefishes are distinguished by their elongated, paddle-shaped snouts.21
Many species of sturgeons are critically endangered due to overfishing and habitat degradation. They are valued for their flesh, eggs (caviar), and swim bladders, which are used to produce isinglass.2
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fishAnnotated classificationOrder Acipenseriformes (sturgeons and paddlefishes) Almost no internal ossification; scales as large scutes in isolated rows (Acipenseridae); snout enlarged and tactile (Polyodontidae); median fins chondrostean in having more fin rays than basal elements; tail heterocercal. Length (sturgeons) up to 6 metres (roughly 20 feet), weight to…
Read MoreOrder Acipenseriformes (sturgeons and paddlefishes) Almost no internal ossification; scales as large scutes in isolated rows (Acipenseridae); snout enlarged and tactile (Polyodontidae); median fins chondrostean in having more fin rays than basal elements; tail heterocercal. Length (sturgeons) up to 6 metres (roughly 20 feet), weight to…
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chondrosteanAnnotated classificationOrder AcipenseriformesEndoskeleton formed largely of cartilage, scale covering of the body greatly reduced, fin rays outnumber the internal supports, tail heterocercal, notochord persistent, intestine retains a spiral valve. 2 living families. Middle Jurassic to present.Family Acipenseridae (sturgeons)Body
Read MoreOrder AcipenseriformesEndoskeleton formed largely of cartilage, scale covering of the body greatly reduced, fin rays outnumber the internal supports, tail heterocercal, notochord persistent, intestine retains a spiral valve. 2 living families. Middle Jurassic to present.Family Acipenseridae (sturgeons)Body
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- chondrostean
… (family Polyodontidae) in the order Acipenseriformes. Some taxonomies also include the bichirs and reedfish of Africa (order Polypteriformes), but this remains a subject of much debate. Many taxonomists argue that the subclass Chondrostei is a paraphyletic group—that is, a taxonomic group that does not include all descendants of a common…
Read More… (family Polyodontidae) in the order Acipenseriformes. Some taxonomies also include the bichirs and reedfish of Africa (order Polypteriformes), but this remains a subject of much debate. Many taxonomists argue that the subclass Chondrostei is a paraphyletic group—that is, a taxonomic group that does not include all descendants of a common…
Read More - chondrosteanEvolution
The origin of the order Acipenseriformes (which contains the sturgeons and paddlefishes) is not known for certain, although its members were clearly derived from some palaeonisciform groups. Fossils that are without doubt related to the sturgeons and paddlefishes date back to the Middle Jurassic Epoch (about 174 million to 163.5…
Read MoreThe origin of the order Acipenseriformes (which contains the sturgeons and paddlefishes) is not known for certain, although its members were clearly derived from some palaeonisciform groups. Fossils that are without doubt related to the sturgeons and paddlefishes date back to the Middle Jurassic Epoch (about 174 million to 163.5…
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