Sandbar shark

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Sandbar shark
Carcharhinus plumbeus georgia.jpg
Scientific classification OOjs UI icon edit-ltr.svg
Domain: Eukaryota
Kingdom: Animalia
Phylum: Chordata
Class: Chondrichthyes
Subclass: Elasmobranchii
Subdivision: Selachimorpha
Order: Carcharhiniformes
Family: Carcharhinidae
Genus: Carcharhinus
Species:
C. plumbeus
Binomial name
Carcharhinus plumbeus
(Nardo, 1827)
Carcharhinus plumbeus distmap.png
Range of the sandbar shark

The sandbar shark (Carcharhinus plumbeus), also known as the brown shark or thickskin shark, is a species of requiem shark, and part of the family Carcharhinidae, native to the Atlantic Ocean and the Indo-Pacific. It is distinguishable by its very high first dorsal fin and interdorsal ridge. [2] It is not to be confused with the similarly named sand tiger shark, or Carcharias taurus.

Contents

Description and growth

Upper teeth Carcharhinus plumbeus upper teeth.jpg
Upper teeth
Lower teeth Carcharhinus plumbeus lower teeth.jpg
Lower teeth

The sandbar shark is one of the largest coastal sharks in the world, and is closely related to the dusky shark, the bignose shark, and the bull shark. Its dorsal fin is triangular and very high, and it has very long pectoral fins. Sandbar sharks usually have heavy-set bodies and rounded snouts that are shorter than the average shark's snout. Its upper teeth have broadly uneven cusps with sharp edges. Its second dorsal fin and anal fin are close to the same height.

Females can grow to 2–2.5 m (6.6–8.2 ft), males up to 1.8 m (5.9 ft). The maximum recorded weight is 240 kg (530 lb). [3] Female sandbar sharks have an average fork-length (tip of the nose to fork in the tail) of 154.9 cm with the males' average fork-length being 151.6 cm. [4] Its body color can vary from a blue-ish brown, grey or bronze, with a white or pale underside. Sandbar sharks swim alone or gather in sex-segregated schools that vary in size.

Distribution and habitat

The sandbar shark, true to its nickname, is commonly found over muddy or sandy bottoms in shallow coastal waters such as bays, estuaries, harbors, or the mouths of rivers, but it also swims in deeper waters (200 m or more) as well as intertidal zones. Sandbar sharks are found in tropical to temperate waters worldwide; in the western Atlantic they range from Massachusetts to Brazil. Juveniles are common to abundant in the lower Chesapeake Bay, and nursery grounds are found from Delaware Bay to South Carolina. Other nursery grounds include Bonjuk Bay in Marmaris, Muğla/Turkey [5] and the Florida Keys. [6]

Predators and diet

Natural predators of the sandbar shark include the tiger shark and, rarely, great white sharks.

The sandbar shark itself preys on fish, rays, crabs, and molluscs. [7] They have also been found to primarily consume osteichthyes, or bony fish, octopi, european squid, and cuttlefish when in areas such as the Mediterranean or the Gulf of Gabés. [8] Sandbar sharks have been described as being a top predator in their ecosystem's food chain. [9]

In captivity Sandbar shark seaworld.jpg
In captivity

Maturity and reproduction

There are disagreements about when exactly sandbar sharks reach sexual maturity, but most studies conclude that females reach sexual maturity around 13 years of age, while males tend to reach maturity around age 12 years old. [10] Sandbar sharks are viviparous, with the embryos supported in placental yolk sac inside the mother. Females have been found to exhibit both biennial, consistently reproducing every two years and returning to the same place to have deliver the pup, and triennial, reproducing every three years and returning to the same place for delivery, migration and gestation periods. They also ovulate in early summer, and give birth to an average of eight pups, which they carry for 1 year before giving birth. [4] The longevity of the sandbar shark is typically 35–41 years. [11]

Interactions with humans

Captured shark Carcharhinus plumbeus.jpg
Captured shark

Fishing restrictions

Sandbar sharks have been disproportionately targeted by the U.S. commercial shark fisheries in recent decades due to their high fin-to-body weight ratio, and U.S. fishing regulation requiring carcasses to be landed along with shark fins. In 2008, the National Marine Fisheries Service banned all commercial landings of sandbar sharks based on a 2006 stock assessment by SEDAR, and sandbar sharks were listed as vulnerable, due to overfishing. Currently, a small number of specially permitted vessels fish for sandbar sharks for the purpose of scientific research. All vessels in the research fishery are required to carry an independent researcher while targeting sandbars. [6]

Danger to people

In spite of their large size and similar appearance to other dangerous sharks such as bull sharks, sandbar sharks are not considered to be dangerous to people. Very few, if any attacks are attributed to sandbar sharks. As a result, they are considered one of the safest sharks to swim with and are popular sharks for aquaria. However, on August 2, 2021, a 12-year-old girl was bitten on her leg by a sandbar shark in Ocean City, Maryland, USA. This was confirmed by Ocean City authorities on August 5, 2021. The victim required 42 stitches. [12]

Immune system studies

Immune system genes, specifically MHC genes, are under study to understand the adaptive immune system in sharks such as the sandbar. [13] Sandbars contain MHC class I, MHC class IIα, and class IIβ genes. Shark MHC genes are known to be similar to tetrapod rather than fish. Similarities include the lack of cysteines in class IIα1 domains in tetrapods and carcharhinids. Also, there are a fewer number of classical loci in sharks and tetrapods, when compared to other animals.

Conservation status

The New Zealand Department of Conservation has classified the sandbar shark as "Data Deficient" under the New Zealand Threat Classification System. [14]

See also

Related Research Articles

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The oceanic whitetip shark is a large pelagic requiem shark inhabiting tropical and warm temperate seas. It has a stocky body with long, white-tipped, rounded fins. The species is typically solitary, though they may gather in large numbers at food concentrations. Bony fish and cephalopods are the main components of its diet and females give live birth.

<span class="mw-page-title-main">Silky shark</span> Species of fish

The silky shark, also known by numerous names such as blackspot shark, gray whaler shark, olive shark, ridgeback shark, sickle shark, sickle-shaped shark and sickle silk shark, is a species of requiem shark, in the family Carcharhinidae, named for the smooth texture of its skin. It is one of the most abundant sharks in the pelagic zone, and can be found around the world in tropical waters. Highly mobile and migratory, this shark is most often found over the edge of the continental shelf down to 50 m (164 ft). The silky shark has a slender, streamlined body and typically grows to a length of 2.5 m. It can be distinguished from other large requiem sharks by its relatively small first dorsal fin with a curving rear margin, its tiny second dorsal fin with a long free rear tip, and its long, sickle-shaped pectoral fins. It is a deep, metallic bronze-gray above and white below.

<span class="mw-page-title-main">Copper shark</span> Species of shark

The copper shark, bronze whaler, or narrowtooth shark is a species of requiem shark found mostly in temperate latitudes. It is distributed in a number of separate populations in the northeastern and southwestern Atlantic, off southern Africa, in the northwestern and eastern Pacific, and around Australia and New Zealand, with scattered reports from equatorial regions. The species can be found from brackish rivers and estuaries to shallow bays and harbors, to offshore waters 100 m (330 ft) deep or more. Females are found apart from males for most of the year, and conduct seasonal migrations. A large species reaching 3.3 m (11 ft) long, the copper shark is difficult to distinguish from other large requiem sharks. It is characterized by its narrow, hook-shaped upper teeth, lack of a prominent ridge between the dorsal fins, and plain bronze coloration.

<span class="mw-page-title-main">Dusky shark</span> Species of shark

The dusky shark is a species of requiem shark, in the family Carcharhinidae, occurring in tropical and warm-temperate continental seas worldwide. A generalist apex predator, the dusky shark can be found from the coast to the outer continental shelf and adjacent pelagic waters, and has been recorded from a depth of 400 m (1,300 ft). Populations migrate seasonally towards the poles in the summer and towards the equator in the winter, traveling hundreds to thousands of kilometers. One of the largest members of its genus, the dusky shark reaches more than 4 m (13 ft) in length and 350 kg (770 lb) in weight. It has a slender, streamlined body and can be identified by its short round snout, long sickle-shaped pectoral fins, ridge between the first and second dorsal fins, and faintly marked fins.

<span class="mw-page-title-main">Blacktip shark</span> Species of shark

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).

<span class="mw-page-title-main">Caribbean reef shark</span> Species of shark

The Caribbean reef shark is a species of requiem shark, belonging to the family Carcharhinidae. It is found in the tropical waters of the western Atlantic Ocean from Florida to Brazil, and is the most commonly encountered reef shark in the Caribbean Sea. With a robust, streamlined body typical of the requiem sharks, this species is difficult to tell apart from other large members of its family such as the dusky shark and the silky shark. Distinguishing characteristics include dusky-colored fins without prominent markings, a short free rear tip on the second dorsal fin, and tooth shape and number.

<span class="mw-page-title-main">Blacknose shark</span> Species of shark

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.

<span class="mw-page-title-main">Bignose shark</span> Species of shark

The bignose shark is a species of requiem shark, in the family Carcharhinidae. Distributed worldwide in tropical and subtropical waters, this migratory shark frequents deep waters around the edges of the continental shelf. It is typically found at depths of 90–430 m (300–1,410 ft), though at night it may move towards the surface or into shallower water. The bignose shark is plain-colored and grows to at least 2.7–2.8 m (8.9–9.2 ft) in length. It has a long, broad snout with prominent nasal skin flaps, and tall, triangular upper teeth. Its pectoral fins are long and almost straight, and there is a ridge on its back between the two dorsal fins.

<span class="mw-page-title-main">Hardnose shark</span> Species of shark

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.

<span class="mw-page-title-main">Creek whaler</span> Species of shark

The creek whaler is a common species of requiem shark, and part of the family Carcharhinidae, endemic to northern Australia. It frequents shallow waters close to shore, including estuaries. This small, stocky shark usually grows to 1.0–1.3 m (3.3–4.3 ft) long and is brownish in color without conspicuous fin markings. It can be identified by its long snout, large, triangular pectoral fins, and large, anteriorly positioned first dorsal fin.

<span class="mw-page-title-main">Spinner shark</span> Species of shark

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<span class="mw-page-title-main">Nervous shark</span> Species of shark

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The blackspot shark is a small species of requiem shark in the family Carcharhinidae found in the tropical Indo-West Pacific Ocean between latitudes 24°N and 30°S, from the surface to a depth around 40 m (130 ft). Its length is a little under one meter (yard) and it is not considered to be dangerous to humans. It feeds mainly on fish, crustaceans, and squid. This shark is also caught in small-scale fisheries for human consumption.

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<span class="mw-page-title-main">Spot-tail shark</span> Species of shark

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.

<span class="mw-page-title-main">Australian blacktip shark</span> Species of shark

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.

<span class="mw-page-title-main">Milk shark</span> Species of shark

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.

References

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  12. "Girl's injuries consistent with shark bite, a Maryland first". Yahoo! News.
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  14. Duffy, Clinton A. J.; Francis, Malcolm; Dunn, M. R.; Finucci, Brit; Ford, Richard; Hitchmough, Rod; Rolfe, Jeremy (2018). Conservation status of New Zealand chondrichthyans (chimaeras, sharks and rays), 2016 (PDF). Wellington, New Zealand: Department of Conservation. p. 9. ISBN   9781988514628. OCLC   1042901090.