Ground Sharks, an order belonging to the Elasmobranchs, includes most of the known shark species. They are usually found in tropical regions and are associated with both coral reefs and open waters.
They are characterized by a long body, with an extended snout in which the mouth extends beyond the eye level. The dentition of these species is very varied, ranging from numerous small, pointed or flattened teeth, depending on their feeding habits, to large, blade-shaped teeth, as is the case of the great white shark (Carcharodon carcharias). They have two dorsal fins, an anal fin and 5 gill slits, the last one to the last 3 of which are located at the level of the pectoral fins.
Another distinctive feature of Ground Sharks is their eyes, which are equipped in most species with a protective membrane called nictitating membrane.
Regarding the reproduction of Ground Sharks, there is much variability, with oviparous, ovoviviparous and viviparous species.
The total of 284 species of Ground Sharks are classified into 8 families (Carcharhinidae, Hemigaleidae, Leptochariidae, Proscylliidae, Pseudotriakidae, Scyliorhinidae, Sphyrnidae, Triakidae) and 51 genera. There is some controversy, and it is likely that if the latest molecular studies are confirmed, some of the genera and families are not monophyletic, that is to say, they may have evolved from an ancestor not common to the rest of the genera and families, and therefore are candidates for exclusion from this order.