Original: There are 52 species divided among two orders, the Acipenseriformes (sturgeons and paddlefishes) and the Polypteriformes (reedfishes and bichirs).
Simplified: There are 52 species divided among two orders. The orders are the Acipenseriformes (sturgeons and paddlefishes), and the Polypteriformes (reedfishes and bichirs).