Requiem shark

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) such as 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 viviparous, 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. 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. The 60 species of requiem shark are grouped into 12 genera: † = extinct