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〕 | image = Shovelnose Sturgeon 01-19-08 1241.jpg | image_width = 250px | image_caption = | regnum = Animalia | phylum = Chordata | classis = Actinopterygii | ordo = Acipenseriformes | familia = Acipenseridae | genus = ''Scaphirhynchus'' | species = ''S. platorynchus'' | binomial = ''Scaphirhynchus platorynchus'' | binomial_authority = (Rafinesque, 1820) | synonyms = ''Acipenser platorynchus'' Rafinesque 1820 }} The shovelnose sturgeon, ''Scaphirhynchus platorynchus'', is the smallest species of freshwater sturgeon native to the United States of America. It is often called "hackleback", "sand sturgeon", or "switchtail." Switchtail refers to the long filament found on the upper lobe of the caudal fin (often broken off as adults). Shovelnose sturgeon are the most abundant sturgeon, found in the Missouri River and Mississippi River systems, and the only commercially fished sturgeon in the United States of America (Pflieger 1997). ==Description== The sturgeons of the family Acipenseridae have bony scutes along the sides and back and four barbels on the underside of the rostrum. A total of 25 extant species of sturgeon are recognized, including 17 within the genus ''Acipenser''. Sturgeon are distributed around the northern part of the Northern Hemisphere (holarctic distribution) and have marine, freshwater, and anadromous members. Sturgeons, including the shovelnose, are highly regarded for their flesh and their roe, from which premium grades of caviar are made (Barton 2007). They can reach 1m in length and up to 4.8kg in weight but 50–85cm and 2.5kg is more common. The scientific name ''Scaphirhynchus'', Greek, means "spade snout," and ''platorynchus'', Greek, means "broad snout." The shovelnose sturgeon is characterized by a long slender filament on the upper lobe of the caudal fin. They have a flattened rostrum (modified snout) that is also shovel shaped. There are four fringed barbels on the ventral side of the rostrum that can be found in a straight line, which is equidistant from the mouth opening to the tip of the snout, unlike pallid sturgeon. The belly of the shovelnose sturgeon is covered with scale-like plates, which is another distinguishing factor from pallid sturgeon who have primarily scaleless bellies. Coloration of the shovelnose sturgeon ranges from a light-brown to buff with a white belly (Pflieger 1997). 抄文引用元・出典: フリー百科事典『 ウィキペディア（Wikipedia）』 ■ウィキペディアで「shovelnose sturgeon」の詳細全文を読む スポンサード リンク
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