匙吻鲟（学名：Polyodon spathula），又名美国匙吻鲟，及“密西西比河的匙吻鲟”，是一种生活在密西西比河缓慢流动水域的匙吻鲟。它似乎已经从伊利湖及其支流灭绝。它们与鲟鱼密切相关。这种大型淡水鱼可以长到220厘米（7英尺），重达100公斤（220磅）。匙吻鲟的名字和学名来自其独特的吻部，呈扁平桨状，特别长。匙吻鲟被认为使用其桨型吻里的感应器检测猎物，以及在迁徙到产卵地时用以导航。匙吻鲟主要以浮游动物，也以甲壳类和双壳类生物为食。

匙吻鲟是目前世界上匙吻鲟科仅存的两属两种之一，另一种为生活在中国长江的白鲟，后者几近灭绝。

The American paddlefish (Polyodon spathula) is a species of basal ray-finned fish closely related to sturgeons in the order Acipenseriformes. Fossil records of paddlefish date back over 300 million years, nearly 50 million years before dinosaurs first appeared. American paddlefish are smooth-skinned freshwater fish commonly called paddlefish, but are also referred to as Mississippi paddlefish, spoon-billed cats, or spoonbills. They are one of only two extant species in the paddlefish family, Polyodontidae. The other is the critically endangered Chinese paddlefish (Psephurus gladius) endemic to the Yangtze River basin in China. American paddlefish are often referred to as primitive fish, or relict species because they retain some morphological characteristics of their early ancestors, including a skeleton that is almost entirely cartilaginous, a paddle-shaped rostrum (snout) that extends nearly one-third their body length, and a heterocercal tail or caudal fin, much like that of sharks. American paddlefish are a highly derived fish because they have evolved with adaptations such as filter feeding. Their rostrum and cranium are covered with tens of thousands of sensory receptors for locating swarms of zooplankton, which is their primary food source.