- a large ganoid fish, Polyodon spathula, of the Mississippi River and its larger tributaries, having a long, flat, paddlelike snout.
- a primitive bony fish, Polyodon spathula, of the Mississippi River, having a long paddle-like projection to the snout: family Polyodontidae
- a similar and related Chinese fish, Psephurus gladius, of the Yangtze River
