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) and include such species as the bull shark, lemon shark, spinner shark, blacknose shark, blacktip shark, grey reef shark, blacktip reef shark, silky shark, dusky shark, blue shark, copper shark, oceanic whitetip shark, and whitetip reef shark.

Requiem sharks
Temporal range:
Blacktip reef shark, Carcharhinus melanopterus
Scientific classification Edit this classification
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Order: Carcharhiniformes
Family: Carcharhinidae
D. S. Jordan & Evermann, 1896
Spinner shark, Carcharhinus brevipinna, from the Gulf of Mexico
Galapagos shark, Carcharhinus galapagensis
Lemon shark, Negaprion brevirostris, at Tiger Beach, Bahamas
Blue shark, Prionace glauca

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 4 m (13 ft) adult length in the oceanic whitetip shark.[1] Scientists assume that the size and shape of their pectoral fins have the right dimensions to minimize transport cost.[2] 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.[3]

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

Etymology

The common name requiem shark 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").

The scientific name Carcharhinidae was first proposed in 1896 by D.S. Jordan and B.W. Evermann as a subfamily of Galeidae (now replaced by "Carcharhinidae").[6][7] The term is derived from Greek κάρχαρος (karcharos, sharp or jagged), and ῥί̄νη (rhinē, rasp); both elements describe the jagged, rasp-like skin.[8] Rasp-like skin is typical of shark skin in general, and is not diagnostic to Carcharhinidae.

Evolutionary history

The oldest member of the family is Archaeogaleus lengadocensis from the Early Cretaceous (Valanginian) of France.[9] Only a handful of records of the group are known from prior to the beginning of the Cenozoic.[10] Modern carcharinid sharks have extensively diversified in coral reef habitats.[11]

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, 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.

Classification

The 59 species of requiem shark are grouped into 11 genera:[1]

† = extinct

See also

References
  1. 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. Iosilevskii, G.; Papastamatiou, Y. P. (2016). "Relations between morphology, buoyancy and energetics of requiem sharks". Royal Society Open Science. 3 (10): 160406. Bibcode:2016RSOS....360406I. doi:10.1098/rsos.160406. PMC 5098981. PMID 27853556.
  3. "Introducing Requiem Sharks". 22 August 2016.
  4. "Species Implicated in Attacks". Florida Museum. 24 January 2018. Retrieved 2 June 2018.
  5. ISAF Statistics on Attacking Species of Shark Archived July 24, 2009, at the Wayback Machine
  6. Subfamily Carcharhininae Jordan & Evermann, 1896 (Family Galeidae), Bull.U.S.Nat.Mus., 48(1):28.
  7. "Family Carcharhinidae Jordan & Evermann, 18961" (PDF). FAO. Retrieved July 31, 2021.
  8. Scharpf, Christopher; Lazara, Kenneth J. (18 January 2013). "Order Carcharhiniformes (Ground Sharks): Families Pentanchidae, Scyliorhinidae, Proscylliidae, Pseudotriakidae, Leptochariidae, Triakidae, Hemigaleidae, Carcharhinidae and Sphyrnidae". The ETYFish Project. Retrieved July 31, 2021.
  9. Guinot, Guillaume; Cappetta, Henri; Adnet, Sylvain (March 2014). "A rare elasmobranch assemblage from the Valanginian (Lower Cretaceous) of southern France". Cretaceous Research. 48: 54–84. Bibcode:2014CrRes..48...54G. doi:10.1016/j.cretres.2013.11.014.
  10. Gates, Terry A.; Gorscak, Eric; Makovicky, Peter J. (2019-01-22). "New sharks and other chondrichthyans from the latest Maastrichtian (Late Cretaceous) of North America". Journal of Paleontology. 93 (3): 512–530. Bibcode:2019JPal...93..512G. doi:10.1017/jpa.2018.92. ISSN 0022-3360. S2CID 198159821.
  11. Sorenson, L.; Santini, F.; Alfaro, M. E. (August 2014). "The effect of habitat on modern shark diversification". Journal of Evolutionary Biology. 27 (8): 1536–1548. doi:10.1111/jeb.12405. PMID 24890604.
  12. "Extinct shark named after LSU museum official as she retires". Washington Post. ISSN 0190-8286. Retrieved 2021-12-25.
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