About Sturgeons and Paddlefishes
Ancient, mostly freshwater cartilaginous-skeletoned fishes yielding caviar.
Acipenseriformes are sturgeons (Acipenseridae) and paddlefishes (Polyodontidae), ancient fishes whose skeleton is largely cartilaginous though they are ray-finned bony fishes.
Morphology. Elongate, nearly scaleless bodies with five rows of bony scutes, a protrusible mouth on the underside, and a heterocercal (shark-like) tail. Paddlefishes have a long paddle-like rostrum.
Habitat & distribution. Large rivers and adjacent seas of the Northern Hemisphere; most are anadromous or live in big rivers and lakes.
Human significance. Sturgeons produce caviar from their roe and were once abundant; overfishing and damming have made most species critically endangered.
