The Mississippi paddlefish Polyodon spathula lives in the slow-flowing waters of the Mississippi River system, feeding on zooplankton by straining them through gill rakers. It may grow to 220 cm and weigh up to 100 kg. Its snout is not only long, but flattened into a paddle shape, thus the name; its purpose is still unclear. Once common throughout the Midwest, overfishing (both the meat and roe are desirable) and river alteration have caused major population declines.

See Paddlefish.