Paddlefish

Polyodon spathula or the American Paddlefish is the only surviving paddlefish species in the world, after the extinction of the Chinese Paddlefish due to overfishing and construction of dams preventing access to spawning areas. A close relative to sturgeons, the paddlefish as a species has been around for at least 125 million years, about the time of the early Cretaceous period. They have highly developed adaptations allowing them to survive basically unchanged since the prehistoric eras. The paddle they are named for is called a 'rostrum', and it contains electroreceptors that allow it to detect electrical signals cast by food sources. Paddlefish are considered vulnerable, being under protection by federal, state, and international laws to try to prevent habitat destruction and overfishing, although the average person is extremely unlikely to catch one on a rod: their diet consists entirely of plankton, swimming with its mouth open to filter them through its gills. Paddlefish are one of the longest lived species of fish, able to live between 14 and 18 years of age, though some individuals have been aged at around 30 years. Perhaps because of this, they spawn every other year or so, and need specific habitat and temperature requirements to do so.