The order of the ground sharks consists of 8 families with more than 259 species. More than half of all known shark species are ground sharks. This order also represents the most typical sharks.
Their distinguishing features are a nicitating membrane (a flap of skin that functions as a third eye lid), 2 dorsal fins, an anal fin and five gill slits.
Most of these sharks are found in tropical and temperate waters.
Ground sharks possess all forms of reproduction such as oviparity, aplacental viviparity (ovoviviparity) and viviparity.