Carcharhinidae

Carcharhinidae, also known as the requiem sharks, is a family of sharks in the order Carcharhiniformes. 
There are currently 60 species of requiem sharks which are grouped into 12 genera. Some of the most familiar species in this family are the lemon shark, the blue shark, the tiger shark, the bull shark, and the whitetip reef shark.
Requiem sharks are found in temperate and tropical oceans, and many species are worldwide. Some live in the open ocean (oceanic whitetip shark), while some live in freshwater rivers and lakes (bull shark).
All species of requiem sharks have a head of normal shape. Their eyes have a nictitating (winking) membranes. They have caudal fins with the upper lobe being larger than the lower but not very long, two spineless dorsal fins, the first one usually much larger than the second in most of the Atlantic species, an anal fin, a caudal peduncle which doesn't have lateral keels, and sharp, bladelike teeth with a single cusp. 
Almost all species of requiem sharks have a similar diet of fish, octopus, marine mammals and seabirds. Since they look similar, it is usually hard to tell one species from another.
Evolutionary history.
The oldest member of the family is from the early Cretaceous of France. Only a few examples of the group are known from before the beginning of the Cenozoic. Modern carcharinid sharks have extensively diversified in coral reef habitats.
Genera.
There are 12 genera in the family Carcharhinidae: