|A tiger shark, Galeocerdo cuvier|
D. S. Jordan & Evermann, 1896
Requiem sharks are sharks of the family Carcharhinidae in the order Carcharhiniformes. They are migratory, live-bearing sharks of warm seas (sometimes of brackish or fresh water) and includes such species as the tiger shark, the spinner shark, the blacknose shark, the blacktip shark, the grey reef shark, the blacktip reef shark, and the Oceanic whitetip shark.
The name may be related to the French word for shark, requin, which is itself of disputed etymology. One derivation of the latter is from Latin requiem ("rest"), which would thereby create a cyclic etymology (requiem-requin-requiem), but other sources derive it from the verb reschignier ("to grimace while baring teeth").
Family members have the usual carcharhiniform characteristics. Their eyes are round, and one or two gill slits fall over the pectoral fin base. Most species are ovoviviparous, the young being born fully developed. They vary widely in size, from as small as 69 cm (2.26 ft) adult length in the Australian sharpnose shark, up to 5.5 m (18 ft) adult length in the tiger shark. Scientists assume that size and shape of their pectoral fins have just the right dimension that minimizes transport cost. They tend to live in more tropical areas but love to migrate. The females release a chemical in the ocean in order to let the males know they are ready to mate. Typical mating time for these sharks are around spring to autumn. 
Requiem sharks are involved in a large proportion of attacks on humans, among the top five species; however, due to the difficulty in identifying individual species, a degree of inaccuracy exists in attack records.
Requiem sharks are incredibly fast and effective hunters. Their elongated, torpedo-shaped bodies make them quick and agile swimmers, so they can easily attack any prey. They have a range of food sources depending on their location and species that includes bony fish, squids, octopuses, lobsters, turtles, marine mammals, seabirds, other sharks and rays. They are often considered the 'garbage cans' of the seas because they will eat almost anything, even non-food items like trash. They are migratory hunters that follow their food source across entire oceans. They tend to be most active at night time, where their impressive eyesight can help them sneak up on unsuspecting prey. Most Requiem sharks hunt alone, however some species like the Whitetip reef sharks and Lemon sharks are cooperative feeders and will hunt in packs through coordinated, timed attacks against their prey.
The 60 species of requiem shark are grouped into 12 genera:
+ = extinct