Ground shark

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

Members of the orders 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 traditional groups are not monophyletic.

Families

 * Carcharhinidae (requiem sharks)
 * Hemigaleidae (weasel sharks)
 * Leptochariidae (barbeled houndshark)
 * Proscylliidae (finback cat sharks)
 * Pseudotriakidae (false cat sharks)
 * Scyliorhinidae (cat sharks)
 * Sphyrnidae (hammerhead sharks)
 * Triakidae (hound sharks)