Requiem shark

Requiem sharks are members in the family Carcharhinidae. They are migratory, live-bearing sharks of warm seas (sometimes of Brackish water or fresh water) and include such species as the blacktip shark, bull shark, lemon shark, nervous shark, and whitetip reef shark. Family members have the usual carcharhiniform characteristics. Their eyes are round, and one or two gill slits fall over the pectoral fin base. All 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 4 m (13 ft) adult length in the oceanic whitetip shark. Scientists assume that the size and shape of their pectoral fins have the right dimensions to minimize transport cost. Requiem sharks tend to live in more tropical areas, but tend to migrate. 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 is around spring to autumn. According to the ISAF, requiem sharks are among the top five species involved in shark attacks on humans; however, "requiem shark" is not a single species, but refers, in this case, to an order of similar sharks that are often involved in incidents. ISAF prefers to use "requiem sharks" due to the difficulty in identifying individual species.