|Image from Texas Parks and Wildlife|
The protruding…thingy (actually called a rostrum) from which the Paddlefish gets its name is covered with electroreceptors to help it find groups of zooplankton on which it feeds. The minute prey are swept unceremoniously from the water by the gaping maw of the Paddlefish, and then filtered from the water by raking protrusions on the gills. The fish’s mouth is specifically designed to open to an immense size to filter the largest amount of water possible. Wikipedia suggests that the rostrum also acts as a hydrofoil to help keep the head level in the water as filter feeding occurs, but I don’t really like to cite them as a source.
The American Paddlefish live in rivers, so of course dams affect their populations by impeding their moving patterns. Much like the sturgeon, they have been harvested for meat, and their eggs have been harvested for caviar. Agricultural runoff causes the streams to silt up, making filter feeding a difficult prospect. To help relieve some of these threats, farm-raised Paddlefish are released into the wild. Stricter regulations on Paddlefish harvesting have also been put into effect.
1Still no blog, so here’s her sister’s link again.