Requiem sharks Temporal range: | |
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Blacktip reef shark, Carcharhinus melanopterus | |
Scientific classification | |
Domain: | Eukaryota |
Kingdom: | Animalia |
Phylum: | Chordata |
Class: | Chondrichthyes |
Subclass: | Elasmobranchii |
Order: | Carcharhiniformes |
Suborder: | Carcharhinoidei |
Family: | Carcharhinidae 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 include such species as the bull shark, lemon shark, blacktip 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. 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]
According to the ISAF, requiem sharks are among the top five species involved in shark attacks on humans; [4] 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. [5]
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.
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]
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. Some species are continually active, while others are capable of resting motionless for extended periods on the bottom. They have a range of food sources depending on location and species, including bony fish, squid, octopus, lobster, turtles, marine mammals, seabirds, other sharks and rays; smaller species tend to select a narrow range of prey, but some very large species, especially the tiger shark (Galeocerdo cuvier), are virtually omnivorous. [7] They are often considered the "garbage cans" of the seas because they will eat almost anything, even non-food items like trash. [7] They are migratory hunters that follow their food source across entire oceans. They tend to be most active at night time, [7] where their impressive eyesight can help them sneak up on unsuspecting prey. It is worth mentioning that the tiger shark, however, possibly belongs to the Galeocerdidae family. [12] 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. Some of the species have been shown to give specialized displays when confronted by divers or other sharks, which may be indicative of aggressive or defensive threat. [7]
The 60 species of requiem shark are grouped into 11 genera: [1]
† = extinct
Glyphis is a genus in the family Carcharhinidae, commonly known as the river sharks. They live in rivers or coastal regions in and around south-east Asia, Africa and parts of Australia.
The whitetip reef shark is a species of requiem shark, in the family Carcharhinidae, and the only member of its genus. A small shark that does not usually exceed 1.6 m (5.2 ft) in length, this species is easily recognizable by its slender body and short but broad head, as well as tubular skin flaps beside the nostrils, oval eyes with vertical pupils, and white-tipped dorsal and caudal fins. One of the most common sharks found on Indo-Pacific coral reefs, the whitetip reef shark occurs as far west as South Africa and as far east as Central America. It is typically found on or near the bottom in clear water, at a depth of 8–40 m (26–131 ft).
John Andrew Frank Garrick was a New Zealand ichthyologist.
The blacktip shark is a species of requiem shark, and part of the family Carcharhinidae. It is common to coastal tropical and subtropical waters around the world, including brackish habitats. Genetic analyses have revealed substantial variation within this species, with populations from the western Atlantic Ocean isolated and distinct from those in the rest of its range. The blacktip shark has a stout, fusiform body with a pointed snout, long gill slits, and no ridge between the dorsal fins. Most individuals have black tips or edges on the pectoral, dorsal, pelvic, and caudal fins. It usually attains a length of 1.5 m (4.9 ft).
Scoliodon is a genus of requiem sharks in the family Carcharhinidae. It was formerly thought to include only a single Indo-Pacific species, the spadenose shark, but recent taxonomic research has found an additional species, the Pacific spadenose shark.
Lamiopsis is a genus of shark in the family Carcharhinidae found in Indian and Pacific Ocean. This genus was previously considered to be monotypic. However, a recent taxonomic study revealed that the western central Pacific populations were a separate species.
The speartooth shark is a rare species of river shark, belonging to the family Carcharhinidae. It inhabits coastal marine waters and tidal reaches of large tropical rivers in northern Australia and New Guinea. Despite being a member of the river shark genus, it is also found in near-shore marine waters, favoring highly turbid environments over a wide range of salinities. This robustly built, gray-colored shark is characterized by a short and broad snout, tiny eyes, a relatively large second dorsal fin, and a black blotch beneath each pectoral fin near the tip. Another identifying trait is its teeth, which are large, triangular, and serrated in the upper jaw and narrow, spear-like, and serrated only near the tips in the lower jaw. Adults grow to about 2.6 m (8.5 ft) long.
The blacknose shark is a species of requiem shark, belonging to the family Carcharhinidae, common in the tropical and subtropical waters of the western Atlantic Ocean. This species generally inhabits coastal seagrass, sand, or rubble habitats, with adults preferring deeper water than juveniles. A small shark typically measuring 1.3 m (4.3 ft) long, the blacknose has a typical streamlined "requiem shark" shape with a long, rounded snout, large eyes, and a small first dorsal fin. Its common name comes from a characteristic black blotch on the tip of its snout, though this may be indistinct in older individuals.
The hardnose shark is a species of requiem shark, in the family Carcharhinidae, so named because of the heavily calcified cartilages in its snout. A small bronze-coloured shark reaching a length of 1.1 m (3.6 ft), it has a slender body and a long, pointed snout. Its two modestly sized dorsal fins have distinctively elongated rear tips. The hardnose shark is widely distributed in the western Indo-Pacific, from Kenya to southern China and northern Australia. It inhabits warm, shallow waters close to shore.
The spinner shark is a type of requiem shark, in the family Carcharhinidae, named for the spinning leaps it makes as a part of its feeding strategy. This species occurs in tropical and warm temperate waters worldwide, except for in the eastern Pacific Ocean. It is found from coastal to offshore habitats to a depth of 100 m (330 ft), though it prefers shallow water. The spinner shark resembles a larger version of the blacktip shark, with a slender body, long snout, and black-marked fins. This species can be distinguished from the blacktip shark by the first dorsal fin, which has a different shape and is placed further back, and by the black tip on the anal fin. It attains a maximum length of 3 m (9.8 ft).
The Pondicherry shark is an extremely rare species of requiem shark, in the family Carcharhinidae. A small and stocky gray shark, it grows not much longer than 1 m (3.3 ft) and has a fairly long, pointed snout. This species can be identified by the shape of its upper teeth, which are strongly serrated near the base and smooth-edged near the tip, and by its first dorsal fin, which is large with a long free rear tip. Furthermore, this shark has prominent black tips on its pectoral fins, second dorsal fin, and caudal fin lower lobe.
The spot-tail shark, or sorrah shark, is a species of requiem shark, in the family Carcharhinidae, found in the tropical Indo-West Pacific Ocean between latitudes 31°N and 31°S from the surface to a depth around 72 m (236 ft). This shark grows to about 1.6 m. It is fished commercially over much of its range and the IUCN considers it to be near threatened.
The Australian blacktip shark is a species of requiem shark, in the family Carcharhinidae, endemic to northern and eastern Australia. Favoring the upper and middle parts of the water column, it can be found from the intertidal zone to a depth of 50 m (160 ft). Appearance-wise this species is virtually identical to the common blacktip shark, from which it can be reliably distinguished only by its lower vertebra number and by genetic markers. Generally reaching 1.5–1.8 m (4.9–5.9 ft) in length, it is a fairly stout-bodied, bronze-colored shark with a long snout and black-tipped fins.
The milk shark is a species of requiem shark, and part of the family Carcharhinidae, whose common name comes from an Indian belief that consumption of its meat promotes lactation. The largest and most widely distributed member of its genus, the milk shark typically measures 1.1 m (3.6 ft) long, and can be found in coastal tropical waters throughout the eastern Atlantic and the Indo-Pacific regions. Occurring from the surface to a depth of 200 m (660 ft), this species is common near beaches and in estuaries, and has been recorded swimming up rivers in Cambodia. Juveniles are known to inhabit tidal pools and seagrass meadows. The milk shark has a slender body with a long, pointed snout and large eyes, and is a nondescript gray above and white below. This shark can be distinguished from similar species in its range by the long furrows at the corners of its mouth, and seven to 15 enlarged pores just above them.
Rhizoprionodon is a genus of requiem sharks, and part of the family Carcharhinidae, commonly known as sharpnose sharks because of their long, pointed snouts.
Negaprion is a genus of requiem sharks in the family Carcharhinidae. It contains the two extant species of lemon sharks: the lemon shark of the Americas, and the sicklefin lemon shark of the Indo-Pacific. Both species are large, slow-moving, bulky sharks inhabiting shallow coastal waters, and can be identified by their short, blunt snouts, two dorsal fins of nearly equal size, and uniform yellowish brown or gray coloration.
Carcharias is a genus of mackerel sharks belonging to the family Odontaspididae. Once bearing many prehistoric species, all have gone extinct with the exception of the critically endangered sand tiger shark.
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: CS1 maint: multiple names: authors list (link)Compagno, Leonard J.V. (1984). FAO species catalogue Vol.4. Sharks of the world. An annotated and illustrated catalogue of shark species known to date. Part 2. Carcharhiniformes (PDF). Rome: Food and Agriculture Organization of the United Nations. ISBN 9251013837.