Order-Animalia: Carcharhiniformes

Carcharhiniformes, the ground sharks, with over 270 species, are the largest order of sharks. They include a number of common types, such as catsharks, swellsharks, and the sandbar shark.

Members of this order are characterized by the presence of a nictitating membrane over the eye, two dorsal fins, an anal fin, and five gill slits.

The families in the order Carcharhiniformes are expected to be revised; recent DNA studies show that some of the conventional groups are not monophyletic.

Reference: Wikipedia