Brief Summary

provided by EOL authors
Requiem sharks - the Carcharhinids - are distributed throughout temperate and tropical oceans with several species occurring worldwide. Habitats are oceanic beyond the continental shelf (oceanic whitetip sharks, Carcharhinus longimanus) and inland into freshwater rivers and lakes (bull sharks, Carcharhinus leucas). Some species tend to associate with bottom while others range throughout the water column. All carcharhinids are viviparous or ovoviviparous (Compagno, 1984). Carcharhinid sharks are a valuable resource worldwide. They are utilized for their flesh, fins, oil, and skin, and are taken recreationally (Bonfil, 1994). Some species are known to travel long distances, occasionally crossing oceans, and are considered to be a resource shared between regions and nations. Carcharhinidae genera can be difficult to identify due to similar body shape, color, and overlapping distributions; particularly Carcharhinus species and Rhizoprionodon species. There are a number of shark identification keys and field guides that are invaluable for carcharhinid identifications and those works are fundamental for providing a format for accurate identifications (Bigelow and Schroeder, 1948; Baughman and Springer, 1950; Springer, 1950; Casey, 1964; Clark and von Schmidt, 1965; Schwartz and Burgess, 1975; Hoese and Moore, 1977; Boschung, 1979; Garrick, 1982, 1985; Castro, 1983; Compagno, 1984; Gar­ man, 1997; McEachran and Fechhelm, 1998). Members of Carcharhinidae are variously distinguished by the presence of precaudal pits; lack of spiracles (present on tiger sharks and occurring rarely on lemon sharks, Compagno, 1988); bladelike teeth with single cusps; first dorsal fin origin usually above pectoral fin or slightly posterior to pectoral fin inner corner (except on the blue shark with the dorsal fin base midpoint closer to pelvic fin origin than pectoral fin axil); second dorsal fin smaller than first dorsal fin and above anal fin (second dorsal fin and first dorsal fin almost equal size on lemon sharks); fifth gill slit over or posterior to pectoral fin origin; no fleshy keels along sides of caudal peduncle (except on tiger sharks and blue sharks); well­ developed nictitating membrane along eye socket lower margin.

Requiem shark

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Blacktip reef shark, Carcharhinus melanopterus
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Spinner shark, Carcharhinus brevipinna, from the Gulf of Mexico
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Galapagos shark, Carcharhinus galapagensis
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Lemon shark, Negaprion brevirostris, at Tiger Beach, Bahamas
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Blue shark, Prionace glauca

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 bull shark, the spinner shark, the blacknose shark, the blacktip shark, the grey reef shark, the blacktip reef shark, the silky shark, the dusky shark, the blue shark, the copper shark, the oceanic whitetip shark and the whitetip reef 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 Old French 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.[1] Scientists assume that size and shape of their pectoral fins have just the right dimension that minimizes transport cost.[2] 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.[3]

Requiem sharks are involved in a large proportion of attacks on humans, among the top five species;[4] however, due to the difficulty in identifying individual species, a degree of inaccuracy exists in attack records.[5]

Hunting strategies

Requiem sharks are extraordinarily 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, seabird, 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.

Classification

The 60 species of requiem shark are grouped into 12 genera:[1]

† = extinct

See also

References

  1. ^ a b Compagno, L.J.V. Family Carcharhinidae - Requiem sharks in Froese, R. and D. Pauly. Editors. 2010. FishBase. World Wide Web electronic publication, version (10/2013).
  2. ^ [1],
  3. ^ http://www.sharksider.com/introducing-requiem-sharks/
  4. ^ "Species Implicated in Attacks". Florida Museum. Retrieved 2 June 2018.
  5. ^ ISAF Statistics on Attacking Species of Shark Archived July 24, 2009, at the Wayback Machine

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Requiem shark: Brief Summary

provided by wikipedia EN
 src= Blacktip reef shark, Carcharhinus melanopterus  src= Spinner shark, Carcharhinus brevipinna, from the Gulf of Mexico  src= Galapagos shark, Carcharhinus galapagensis  src= Lemon shark, Negaprion brevirostris, at Tiger Beach, Bahamas  src= Blue shark, Prionace glauca

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 bull shark, the spinner shark, the blacknose shark, the blacktip shark, the grey reef shark, the blacktip reef shark, the silky shark, the dusky shark, the blue shark, the copper shark, the oceanic whitetip shark and the whitetip reef 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 Old French 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.

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Distribution

provided by World Register of Marine Species
Distribution: global. Gill openings 5, the fifth behind origin of pectoral fin. Small to large sharks with round eyes, internal nictitating eyelids, no nasoral grooves or barbels, usually no spiracles. Teeth usually bladelike with one cusp. Development usually viviparous.

Reference

MASDEA ().

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MASDEA (1997). MASDEA (1997).
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Edward Vanden Berghe [email]