dcsimg

Lifespan, longevity, and ageing

provided by AnAge articles
Maximum longevity: 12 years (wild)
license
cc-by-3.0
copyright
Joao Pedro de Magalhaes
editor
de Magalhaes, J. P.
partner site
AnAge articles

Benefits

provided by Animal Diversity Web

Shark teeth are lost frequently and are prized gifts in many regions of the world. Shark is a delicacy that is eaten in many areas.

Positive Impacts: food ; body parts are source of valuable material; ecotourism ; research and education

license
cc-by-nc-sa-3.0
copyright
The Regents of the University of Michigan and its licensors
bibliographic citation
Gerlach, G. 2006. "Carcharias taurus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Carcharias_taurus.html
author
Gary Gerlach, Kalamazoo College
editor
Ann Fraser, Kalamazoo College
editor
Tanya Dewey, Animal Diversity Web
original
visit source
partner site
Animal Diversity Web

Associations

provided by Animal Diversity Web

The only know predators of adult grey nurse sharks are humans. Human hunting has caused population declines, both as a result of shark fishing and persecution because their fierce appearance has caused them to be mistaken for other, more dangerous, species of sharks. They are also accidentally caught in commercial fishing nets. Young sharks are eaten by other sharks.

Known Predators:

  • humans (Homo sapiens)
  • other sharks (Chondrichthyes)
license
cc-by-nc-sa-3.0
copyright
The Regents of the University of Michigan and its licensors
bibliographic citation
Gerlach, G. 2006. "Carcharias taurus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Carcharias_taurus.html
author
Gary Gerlach, Kalamazoo College
editor
Ann Fraser, Kalamazoo College
editor
Tanya Dewey, Animal Diversity Web
original
visit source
partner site
Animal Diversity Web

Morphology

provided by Animal Diversity Web

The dorsal side of grey nurse sharks is grey, the underside is a dirty white color. These are stout-bodied sharks with metallic brown or reddish colored spots on the sides. When a grey nurse shark pup is born it is typically between 115 and 150 cm. As they mature, grey nurse sharks can reach 5.5 meters, but an average size is 3.6 meters. Females are generally larger than males. Average weight is from 95 to 110 kg. A distinguishing characteristic of grey nurse sharks is that the anal fin and both dorsal fins are the same size. The tail is heterocercal, with a long, upper lobe and a shorter, lower lobe. These different lobes allow for great movement. The mouth bears razor like teeth and is long and slender, with pointed snout. Their elongated teeth are visible even when the mouth is closed, giving these sharks a menacing appearance. This has led many to believe that these are dangerous sharks, a reputation they don't deserve.

Range mass: 50 to 300 kg.

Average mass: 95-110 kg.

Range length: 6 (high) m.

Average length: 3.6 m.

Range basal metabolic rate: <190 to 311 cm3.O2/g/hr.

Average basal metabolic rate: 239 cm3.O2/g/hr.

Other Physical Features: ectothermic ; heterothermic ; bilateral symmetry

Sexual Dimorphism: female larger

license
cc-by-nc-sa-3.0
copyright
The Regents of the University of Michigan and its licensors
bibliographic citation
Gerlach, G. 2006. "Carcharias taurus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Carcharias_taurus.html
author
Gary Gerlach, Kalamazoo College
editor
Ann Fraser, Kalamazoo College
editor
Tanya Dewey, Animal Diversity Web
original
visit source
partner site
Animal Diversity Web

Life Expectancy

provided by Animal Diversity Web

Little is known about the lifespan of ocean dwelling grey nurse sharks, however those held in captivity live to an average age of thirteen to sixteen years. It is believed that those in the wild live longer still.

Range lifespan
Status: wild:
35 (high) years.

Range lifespan
Status: captivity:
16 (high) years.

license
cc-by-nc-sa-3.0
copyright
The Regents of the University of Michigan and its licensors
bibliographic citation
Gerlach, G. 2006. "Carcharias taurus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Carcharias_taurus.html
author
Gary Gerlach, Kalamazoo College
editor
Ann Fraser, Kalamazoo College
editor
Tanya Dewey, Animal Diversity Web
original
visit source
partner site
Animal Diversity Web

Habitat

provided by Animal Diversity Web

Grey nurse sharks are found in temperate and tropical waters. They are typically found in shallow waters, such as shallow bays, surf zones, and near coral or rocky reefs. They have been sighted in waters as deep as 191 meters, but will most likely be seen in the surf zone to a depth of 60 meters. They are usually found near the bottom of the water column.

Range depth: 2 to 191 m.

Average depth: 60 meters m.

Habitat Regions: temperate ; tropical ; saltwater or marine

Aquatic Biomes: reef ; coastal

Other Habitat Features: estuarine

license
cc-by-nc-sa-3.0
copyright
The Regents of the University of Michigan and its licensors
bibliographic citation
Gerlach, G. 2006. "Carcharias taurus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Carcharias_taurus.html
author
Gary Gerlach, Kalamazoo College
editor
Ann Fraser, Kalamazoo College
editor
Tanya Dewey, Animal Diversity Web
original
visit source
partner site
Animal Diversity Web

Distribution

provided by Animal Diversity Web

Grey nurse sharks, also called sand tiger sharks, can be found in the Atlantic, Indian, and Pacific Oceans in temperate and tropical waters. They are found in warm seas, except for the eastern Pacific. They occur from the Gulf of Maine to Argentina in the western Atlantic, the coast of Europe to north Africa in the eastern Atlantic, in the Mediterranean sea, from Australia to Japan in the west Pacific, and off the coasts of South Africa.

Biogeographic Regions: indian ocean (Native ); atlantic ocean (Native ); pacific ocean (Native ); mediterranean sea (Native )

license
cc-by-nc-sa-3.0
copyright
The Regents of the University of Michigan and its licensors
bibliographic citation
Gerlach, G. 2006. "Carcharias taurus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Carcharias_taurus.html
author
Gary Gerlach, Kalamazoo College
editor
Ann Fraser, Kalamazoo College
editor
Tanya Dewey, Animal Diversity Web
original
visit source
partner site
Animal Diversity Web

Trophic Strategy

provided by Animal Diversity Web

Grey nurse sharks have a range of prey, including bony fish, rays, lobsters, crabs, squid, and other small sharks. Grey nurse sharks sometimes hunt cooperatively, chasing fish into small groups and then attacking them. Grey nurse sharks, like other sharks, have been known to attack at random during feeding frenzies, where a large number of prey is found together. In feeding frenzies sharks rely heavily on their electroreceptors, attacking everything in close vicinity.

Animal Foods: fish; mollusks; aquatic crustaceans

Primary Diet: carnivore (Piscivore , Eats non-insect arthropods)

license
cc-by-nc-sa-3.0
copyright
The Regents of the University of Michigan and its licensors
bibliographic citation
Gerlach, G. 2006. "Carcharias taurus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Carcharias_taurus.html
author
Gary Gerlach, Kalamazoo College
editor
Ann Fraser, Kalamazoo College
editor
Tanya Dewey, Animal Diversity Web
original
visit source
partner site
Animal Diversity Web

Associations

provided by Animal Diversity Web

Grey nurse sharks help to regulate prey populations. Different species of lampreys (Petromyzontidae) prey on these sharks in a parasitic relationship, whereby the lamprey attaches to the shark, and extracts blood and other nutrients through a wound. These sharks also have mutualistic relationships with pilotfish (Naucrates ductor), which clean their gills and, in exchange, get to eat the scraps of food left behind in the gills.

Mutualist Species:

  • pilotfish (Naucrates ductor)

Commensal/Parasitic Species:

  • lampreys (Petromyzontidae)
license
cc-by-nc-sa-3.0
copyright
The Regents of the University of Michigan and its licensors
bibliographic citation
Gerlach, G. 2006. "Carcharias taurus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Carcharias_taurus.html
author
Gary Gerlach, Kalamazoo College
editor
Ann Fraser, Kalamazoo College
editor
Tanya Dewey, Animal Diversity Web
original
visit source
partner site
Animal Diversity Web

Benefits

provided by Animal Diversity Web

Grey nurse sharks are known for their fierce appearance and have gained an undeserved reputation as a man-eater in Australia. These sharks are not generally aggressive, but have been known to bite. Their bites can inflict serious damage because of their size and their dangerous teeth. They are sometimes tangled in fishing nets.

Negative Impacts: injures humans (bites or stings)

license
cc-by-nc-sa-3.0
copyright
The Regents of the University of Michigan and its licensors
bibliographic citation
Gerlach, G. 2006. "Carcharias taurus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Carcharias_taurus.html
author
Gary Gerlach, Kalamazoo College
editor
Ann Fraser, Kalamazoo College
editor
Tanya Dewey, Animal Diversity Web
original
visit source
partner site
Animal Diversity Web

Life Cycle

provided by Animal Diversity Web

It takes a grey nurse shark pup between 6-9 months to develop in the uterus of a female. Young nurse sharks develop a jaw and teeth very early their development and some eat their siblings while still developing within their mother, a phenomenon known as intra-uterine cannibalism. It is uncertain how long it takes grey nurse sharks to reach maturity, but maturity is estimated at between 5 and 13 years. Sharks continue to grow throughout their lives.

Development - Life Cycle: indeterminate growth

license
cc-by-nc-sa-3.0
copyright
The Regents of the University of Michigan and its licensors
bibliographic citation
Gerlach, G. 2006. "Carcharias taurus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Carcharias_taurus.html
author
Gary Gerlach, Kalamazoo College
editor
Ann Fraser, Kalamazoo College
editor
Tanya Dewey, Animal Diversity Web
original
visit source
partner site
Animal Diversity Web

Conservation Status

provided by Animal Diversity Web

Grey nurse sharks were the first shark species to be protected by law. Grey nurse sharks are cited as being critically endangered in the Commonwealth Legislation (Australia). They are also considered endangered in New South Wales. The Queensland Government is hoping to provide a listing in the Nature Conservation Act of 1992 which will give these sharks additional protection. The National Marine Fisheries service in the United States prohibits hunting of these sharks. The IUCN lists grey nurse sharks as a vulnerable species on the red list (last evaluated in 2000). CITES does not have a listing for them, and is the most recently updated (2005). The fact that these sharks live in shallow, accessible waters, have a fierce appearance, and have a low reproductive rate, has contributed to declines in populations. Population declines worldwide are estimated at 20% in the last 10 years.

US Federal List: no special status

CITES: no special status

IUCN Red List of Threatened Species: critically endangered

license
cc-by-nc-sa-3.0
copyright
The Regents of the University of Michigan and its licensors
bibliographic citation
Gerlach, G. 2006. "Carcharias taurus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Carcharias_taurus.html
author
Gary Gerlach, Kalamazoo College
editor
Ann Fraser, Kalamazoo College
editor
Tanya Dewey, Animal Diversity Web
original
visit source
partner site
Animal Diversity Web

Behavior

provided by Animal Diversity Web

Communication among grey nurse sharks is not well understood. Sharks in general are sensitive to electrical and chemical cues.

Grey nurse sharks, and other species of sharks, have pores on their ventral surface. These pores are instrumental in detecting electrical fields, which help them to detect and locate prey and may help in navigating using the earth's magnetic field.

Perception Channels: visual ; tactile ; chemical ; electric

license
cc-by-nc-sa-3.0
copyright
The Regents of the University of Michigan and its licensors
bibliographic citation
Gerlach, G. 2006. "Carcharias taurus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Carcharias_taurus.html
author
Gary Gerlach, Kalamazoo College
editor
Ann Fraser, Kalamazoo College
editor
Tanya Dewey, Animal Diversity Web
original
visit source
partner site
Animal Diversity Web

Reproduction

provided by Animal Diversity Web

Males outnumber females by a 2:1 ratio and multiple males will copulate with a single female. A dominance hierarchy has only been observed in captivity, with the oldest males copulating first.

Mating System: polygynandrous (promiscuous)

Mating occurs in November and October. The gestation period will take anywhere from six to nine months. Females give birth in early spring near coastal, rocky reefs. Caves inhabited by these sharks are also used as breeding grounds and, if disrupted, their breeding may be interrupted. Female sharks bear young once every two years, with a maximum of two shark pups at birth, one from each uterus. Grey nurse sharks are ovoviviparous which means that eggs develop inside of the female in each uterus. Young hatch from the eggs and are retained in the uteri until they are fully developed. Females have hundreds of eggs inside the uterus. When an egg is fertilized the shark pup begins to grow and, at 55 mm, develops a jaw and teeth. This shark then eats the other developing embryos during its 6 to 9 month gestation (intra-uterine cannibalism).

Males mature at a length of 1.95 meters, or 4-5 years in age, and females mature at 2.2 meters, or 6 years in age.

Breeding interval: Grey nurse sharks bear young once every two years.

Breeding season: Shark pups are usually born in early spring (March and April).

Range number of offspring: 1 to 2.

Average number of offspring: 1.

Range gestation period: 6 to 9 months.

Range age at sexual or reproductive maturity (female): 5 to 13 years.

Average age at sexual or reproductive maturity (female): 7-8 years.

Range age at sexual or reproductive maturity (male): 5 to 13 years.

Average age at sexual or reproductive maturity (male): 7-8 years.

Key Reproductive Features: iteroparous ; seasonal breeding ; gonochoric/gonochoristic/dioecious (sexes separate); sexual ; fertilization (Internal ); ovoviviparous

A pup will be born approximately 115-150 cm in length. This shark is able to fend for itself and live without parental care. Intra-uterine cannibalism ensures plenty of energy to the developing pup, resulting in a well-fed and well-developed offspring.

Parental Investment: no parental involvement; pre-fertilization (Provisioning, Protecting: Female); pre-hatching/birth (Provisioning: Female, Protecting: Female)

license
cc-by-nc-sa-3.0
copyright
The Regents of the University of Michigan and its licensors
bibliographic citation
Gerlach, G. 2006. "Carcharias taurus" (On-line), Animal Diversity Web. Accessed April 27, 2013 at http://animaldiversity.ummz.umich.edu/site/accounts/information/Carcharias_taurus.html
author
Gary Gerlach, Kalamazoo College
editor
Ann Fraser, Kalamazoo College
editor
Tanya Dewey, Animal Diversity Web
original
visit source
partner site
Animal Diversity Web

Biology

provided by Arkive
The sand tiger shark is one of the best-studied of the shark species. They are the only sharks known to gulp air at the surface and store it in their stomach to provide buoyancy (2). These sharks generally mate between October and November and courtship can take a long time, with the male aggressively nipping his potential mate (3). Females are ovoviviparous, giving birth to two large pups every two years. Pups hatch out of their eggs within the oviduct of the mother's reproductive system, one in each oviduct, and then feed on eggs that the female continues to produce (6). Over nine months to a year, the pups grow within their mother feeding on hundreds to thousands of eggs (6) and, by the time they are born, measure up to a metre long (3). During the day they are found near caves and ledges (5), hovering just above the surface either singly or in small groups (3). These fairly docile sharks are sluggish and, despite a ferocious reputation, feed mainly on fish (5).
license
cc-by-nc-sa-3.0
copyright
Wildscreen
original
visit source
partner site
Arkive

Conservation

provided by Arkive
Despite protection in some countries such as Australia (2) and the United States (3), this species appears to be in decline (2). Management plans urgently need to be implemented in order to safeguard the future of these elegant coastal dwellers.
license
cc-by-nc-sa-3.0
copyright
Wildscreen
original
visit source
partner site
Arkive

Description

provided by Arkive
This stocky shark has a conical nose and a slightly flattened head (3). It is a dark brown or beige colour above, with blotches of darker colour, and paler underneath (4). The teeth of this species are especially distinctive, having a fang-like appearance and being visible even when the mouth is shut (5). There are two dorsal fins, which are a similar size to the anal fin; the upper lobe of the tail is larger than the lower one (3). Sharks have a sixth sense that enables them to detect electric currents, and the receptive pores are located on the under surface of the sand tiger's snout (5).
license
cc-by-nc-sa-3.0
copyright
Wildscreen
original
visit source
partner site
Arkive

Habitat

provided by Arkive
Inhabits shallow coastal waters from the surf zone to a depth of 60 metres (5).
license
cc-by-nc-sa-3.0
copyright
Wildscreen
original
visit source
partner site
Arkive

Range

provided by Arkive
A widespread range encompasses all subtropical and tropical oceans (6), with the possible exception of the eastern Pacific (2).
license
cc-by-nc-sa-3.0
copyright
Wildscreen
original
visit source
partner site
Arkive

Status

provided by Arkive
Classified as Vulnerable (VU) on the IUCN Red List (1).
license
cc-by-nc-sa-3.0
copyright
Wildscreen
original
visit source
partner site
Arkive

Threats

provided by Arkive
This species of shark is particularly vulnerable to overfishing due to its low reproduction rate (2). Despite a widespread distribution, populations are now isolated and, where there is data available, the species is thought to be in decline. In the past, the sand tiger shark has been hunted throughout its range, and the flesh is particularly prized in Japan (3). The oil and fins are also in demand; in the 18th and 19th Centuries the shark was persecuted in large numbers for its liver oil that was used in lighting (7). Individuals tend to group in coastal areas at certain times of the year, making them especially vulnerable to fishing (3).
license
cc-by-nc-sa-3.0
copyright
Wildscreen
original
visit source
partner site
Arkive

Diagnostic Description

provided by FAO species catalogs
fieldmarks: A large, bulky shark. Head with a flattened-conical snout, eyes without nictitating eyelids, mouth long and extending behind eyes, teeth large, with prominent narrow cusps and lateral cusplets, upper anterior teeth separated from lateral teeth by small intermediate teeth. Anal fin and both dorsal fins equally large and broad-based, first dorsal fin on back closer to pelvic fins than pectorals, upper precaudal pit present but lateral keels absent from caudal peduncle, caudal fin asymmetrical but with a strong ventral lobe. Colour: light brown, often with darker reddish or brownish spots scattered on body. Snout short and somewhat flattened; eyes small; three rows of large upper anterior teeth and usually no symphyseal teeth on each side of symphysis; posterior teeth well differentiated from lateral teeth, with cusps and cusplets reduced or absent, molariform. First dorsal base closer to pelvic bases than to pectoral bases, with its origin well behind inner margins of pectorals and its insertion about over pelvic origins; second dorsal fin about as large as first dorsal; anal fin about as large or slightly larger than dorsal fins and with its origin under midbase of second dorsal. Can be confused with: Included as synonyms of Carcharias taurusare a number of regional species that have often been considered valid in the older literature, but which are most likely local representatives of a single, wide-ranging species. The dental characters most often used to distinguish these species (see Bigelow & Schroeder, 1948) apparently vary considerably within samples from a given area (Applegate, 1965, Sadowsky, 1970, Taniuchi, 1970). These include Squalus americanusand its synonyms from the western North Atlantic, Odontaspis platensis from the western South Atlantic, Carcharias owstoni from the western North Pacific, and Carcharias arenarius from Australia. Abe et al. (1968, 1969), Sadowsky (1970), Taniuchi (1970), and Whitley & Pollard (1980) have all used the species name taurus for the local representatives of the species formerly named owstoni, arenarius, and platensis.

References

  • Bass, D'Aubrey & Kistnasamy, (1975)
  • Cadenat, (1956)
  • Lineaweaver & Backus, (1970)
  • Springer, (1948)
  • Whitley, (1940)

license
cc-by-nc-sa-3.0
bibliographic citation
FAO species catalogue Vol.4. Sharks of the world. An Annotated and Illustrated Catalogue of Shark Species Known to Date Part 1 - Hexanchiformes to Lamniformes. Compagno, L.J.V. 1984. FAO Fish. Synop., (125) Vol.4, Part 1
author
Food and Agriculture Organization of the UN
original
visit source
partner site
FAO species catalogs

Benefits

provided by FAO species catalogs
Generally fished in all areas where it is found, but of variable importance regionally; it is highly regarded for food in Japan but not in the western Atlantic.It is caught primarily with line gear but also fixed bottom gillnets, and in pelagic and bottom trawls . The meat of this shark is utilized fresh, frozen, smoked and dried salted for human consumption; it is also used for fishmeal, its liver for oil, its fins for the oriental sharkfin trade. Sand tiger sharks are easily targeted by fisheries because of their habit to form large mating aggregations at predictable times in specific coastal areas. This makes it possible for these sharks to be easily depleted in a relatively short time. They are also very docile and were senselessly killed in large numbers in the past in Australia by sport divers using power heads. Partly as a result of this habit, sandtigers in New South Wales entered the record books in 1984 as the first fully protected shark species in the world (Pollard 1996). The numbers of sandtiger sharks caught in the New South Wales beach netting decreased from an average of 30 per year in the 1951-1954 period to 1-2 per year in the 1988-1990 period (Stevens 1993; cited by Castroet al. in press). In the United States, Castro et al. (in press) report a severe population decline in the early 1990s, with sandtigers practically disappearing from North Carolina and Florida waters. Off the mouth of Chesapeake Bight in the U.S. Mid-Atlantic coast, sandtiger shark abundance dropped from 1 shark per 100 hooks average in the 1974-1979 period to 0.2 sharks per 100 hooks in 1991 (Musick et al. 1993). Conservation Status : The sandtiger shark has a mid-range intrinsic rebound potential (Smith et al. 1998) suggesting it would not be extremely sensitive to fishing. However, there are at least two documented cases of strong declines in abundance due to excessive fishing (see impact of fisheries section) which might be related to this shark's habit to form easily-targeted mating aggregations. According to the IUCN Red List the sandtiger shark is considered Vulnerable at the world level and Endangered in the NW Atlantic and in Eastern Australia (Camhiet al. 1998). Sandtiger sharks are protected by law and cannot be killed or captured in New South Wales, Queensland, and all Australian Commonwealth waters, and also in all federal waters of the USA coasts of the Gulf of México and the Atlantic Ocean. Additional information from IUCN database Additional information from CITESdatabase
license
cc-by-nc-sa-3.0
bibliographic citation
FAO species catalogue Vol.4. Sharks of the world. An Annotated and Illustrated Catalogue of Shark Species Known to Date Part 1 - Hexanchiformes to Lamniformes. Compagno, L.J.V. 1984. FAO Fish. Synop., (125) Vol.4, Part 1
author
Food and Agriculture Organization of the UN
original
visit source
partner site
FAO species catalogs

Brief Summary

provided by FAO species catalogs
This is a common littoral shark in temperate and tropical waters where it occurs.It ranges from the surf zone, in shallow bays, and around coral and rocky reefs down to at least 191 m depth. This species is often found near or on the bottom but also occurs in midwater or at the surface.It is a strong but slow midwater swimmer that is more active at night. This shark is denser than water, but it swallows air at the surface and holds it in its stomach to maintain approximately neutral buoyancy. Like a bony fish with a swimbladder, it is capable of hovering motionless in the water. It is a very hardy species that readily adapts to captivity and can live for many years and even give birth in adequate tank facilities. This species occurs as solitary individuals or in small to large schools. It is strongly migratory in parts of its range, particularly in its northern and southern extremities where pronounced poleward migrations occur in summer and equatorial movements in fall and winter. Aggregations of individuals occur for feeding, courtship, mating, and birth. Off South Africa courtship and mating apparently occurs in the more tropical parts of its range, while pregnant females give birth in warm-temperate waters. Reproduction in this species is better known than in most other lamnoids and features ovophagy or uterine cannibalism. There are normally two young in a litter, one per uterus. Eggs leave the ovaries, and while in transit in the oviducts are fertilized and enclosed in groups of 16 to 23 in egg cases. However, at some time between fertilization and birth only one embryo of its group prevails, possibly by devouring its rivals, and this proceeds to eat fertilized eggs and smaller potential siblings in utero until birth. Unlike ovoviviparous non-cannibal and viviparous species, the yolk sac is resorbed at a small size, less than 17 cm, and the umbilical scar may be lost. At 17 cm, fetuses have sharp, functional teeth and are feeding; at about 26 cm, they can swim in utero; size at birth is very large, about 1 m. The gestation period may be 8 to 9 months long. This shark is a voracious feeder on a wide variety of bony fishes including herring, croakers, bluefish, bonito, butterfish, snappers, hake, eels, wrasses, mullet, spadefish, sea robins, sea basses, porgies, remoras, sea catfish, flatfish, jacks, and undoubtedly many others, as well as small sharks (Carcharhinidae and Triakidae ), rays (Myliobatidae ), squid, crabs and lobsters . Schools of this shark have been observed to feed cooperatively, surrounding and bunching schooling prey and then feeding on them.
license
cc-by-nc-sa-3.0
bibliographic citation
FAO species catalogue Vol.4. Sharks of the world. An Annotated and Illustrated Catalogue of Shark Species Known to Date Part 1 - Hexanchiformes to Lamniformes. Compagno, L.J.V. 1984. FAO Fish. Synop., (125) Vol.4, Part 1
author
Food and Agriculture Organization of the UN
original
visit source
partner site
FAO species catalogs

Size

provided by FAO species catalogs
Maximum total length about 318 cm, mature males 220 to 257+ cm, mature females 220 to 300+ cm, size at birth 95 to 105 cm.
license
cc-by-nc-sa-3.0
bibliographic citation
FAO species catalogue Vol.4. Sharks of the world. An Annotated and Illustrated Catalogue of Shark Species Known to Date Part 1 - Hexanchiformes to Lamniformes. Compagno, L.J.V. 1984. FAO Fish. Synop., (125) Vol.4, Part 1
author
Food and Agriculture Organization of the UN
original
visit source
partner site
FAO species catalogs

Distribution

provided by FAO species catalogs
Western Atlantic: Gulf of Maine to Florida, northern Gulf of Mexico, Bahamas, Bermuda; southern Brazil to Argentina. Eastern Atlantic: Mediterranean to Canary Islands; Cape Verde Islands, Senegal, Ghana, southern Nigeria to Cameroon. Western Indian Ocean: South Africa to southern Mozambique; Red Sea, Pakistan, ?India. Western Pacific: ?Indonesia, ?VietNam, Japan, China; Australia (Queensland, New South Wales, Victoria, Tasmania, South Australia, Western Australia).
license
cc-by-nc-sa-3.0
bibliographic citation
FAO species catalogue Vol.4. Sharks of the world. An Annotated and Illustrated Catalogue of Shark Species Known to Date Part 1 - Hexanchiformes to Lamniformes. Compagno, L.J.V. 1984. FAO Fish. Synop., (125) Vol.4, Part 1
author
Food and Agriculture Organization of the UN
original
visit source
partner site
FAO species catalogs

Diagnostic Description

provided by Fishbase
A shark with a short, pointed snout, small eyes, protruding spike-like teeth and small, equal-sized dorsal and anal fins; 1st dorsal fin closer to pelvic than to pectoral fins (Ref. 5578). Caudal fin with a pronounced subterminal notch and a short ventral lobe (Ref. 13575). Pale brown or grey, paler below, with dark spots that appear faded in adults; fins plain (Ref. 6586).
license
cc-by-nc
copyright
FishBase
Recorder
Cristina V. Garilao
original
visit source
partner site
Fishbase

Life Cycle

provided by Fishbase
Exhibit ovoviparity (aplacental viviparity), with embryos feeding on other ova produced by the mother (oophagy) after the yolk sac is absorbed, then cannibalize siblings (adelphophagy) (Ref. 50449). Distinct pairing with embrace (Ref. 205). Eggs leave the ovaries, and while in transit in the oviducts are fertilized and enclosed in groups of 16 to 23 in egg cases. However, at some time between fertilization and birth only two (Ref. 5578, 6586) embryos of its group prevails, possibly by devouring its rivals, and proceeds to eat fertilized eggs and smaller potential siblings in utero until birth. According to Springer (1948) (Ref. 39565), it is evident that this species sends forth into the world not only large, well-developed, and even experienced young but may send them forth with a full stomach. The yolk sac is resorbed at a small size, less than 17 cm, and the umbilical scar may be lost. Gestation period may be from 8 to 9 months long. Size at birth 100 cm (Ref. 6586).Pratt (2001) (Ref. 49562) relates Gordon's (1993) (Ref. 51113) detailed account of the mating behavior of the sand tiger sharks as follows: "mating activities began when the two male C. taurus, having become reluctant to feed, increased their swimming speed, accompanied by clasper flexion and eventual interest in their female tank mates...aggressive displays such as snapping and stalking became frequent, mostly toward species of smaller Carcharhinus in the tank. The males did not become interested in the female until she slowed, moved to the sand area and started cupping her pelvic fins. The two males then became competitive toward each other, circling and tailing, until the alpha male forced the beta male out of the sand area. The female bit the male prior to copulation. She exhibited shielding behavior for several days and then resumed cupping and flaring. The female gradually changed her swimming position and began displaying the submissive behavior. The alpha male swam in increasingly larger circles and began splaying its claspers, then approached the female and exhibited tailing and nosing. Copulation occurred as the male bit into the right flank and trailing edge of the pectoral fin of the female. The male swam side by side with the female, copulating with the right clasper for one to two minutes. After copulation, the male showed little interest in the female." In captivity, males show aggression toward other species after copulation (Ref. 51113, 49562). Females avoid patrolling males by 'shielding' with pelvics close to the substrate (Ref. 51113, 49562). However, female acceptance of future male partner is indicated by a show of 'submissive' body, 'cupping' and 'flaring' of pelvic fins (Ref. 51113, 49562).
license
cc-by-nc
copyright
FishBase
Recorder
Susan M. Luna
original
visit source
partner site
Fishbase

Migration

provided by Fishbase
Oceanodromous. Migrating within oceans typically between spawning and different feeding areas, as tunas do. Migrations should be cyclical and predictable and cover more than 100 km.
license
cc-by-nc
copyright
FishBase
Recorder
Kent E. Carpenter
original
visit source
partner site
Fishbase

Morphology

provided by Fishbase
Dorsal spines (total): 0; Dorsal soft rays (total): 0; Analspines: 0; Analsoft rays: 0
license
cc-by-nc
copyright
FishBase
Recorder
Cristina V. Garilao
original
visit source
partner site
Fishbase

Trophic Strategy

provided by Fishbase
A carnivore (Ref. 9137).
license
cc-by-nc
copyright
FishBase
Recorder
Pascualita Sa-a
original
visit source
partner site
Fishbase

Biology

provided by Fishbase
A common littoral shark found inshore from the surf zone and in shallow bays to at least 191 m on the outer continental shelves (Ref. 13568). Often on or near the bottom but also occurs in midwater or at the surface (Ref. 247). Only shark known to gulp and store air in its stomach to maintain neutral buoyancy while swimming (Ref. 13568). Found singly or in small to large schools (Ref. 247). Feeds on bony fishes, small sharks, rays, squids, crabs, and lobsters (Ref. 5578). Ovoviviparous, embryos feeding on yolk sac and other ova produced by the mother as well as other siblings in the womb (uterine cannibalism) (Ref. 50449). Usually gives birth to 2 pups after a 9-12 months gestation period (Ref.58048). A migratory species in parts of its range, particularly in its northern and southern extremities where pronounced poleward migration occur in the summer and equatorial movements in autumn and winter (Ref. 247). Usually inoffensive and not aggressive when not provoked (Ref. 247) but has known to bite swimmers and be aggressive towards divers with speared fish (Ref. 6586). Utilized for fresh, frozen, smoked and dried for human consumption (Ref. 247); also for fishmeal, liver oil, fins, and hides for leather (Ref. 13568). Flesh highly appreciated in Japan (Ref. 36731).
license
cc-by-nc
copyright
FishBase
Recorder
Kent E. Carpenter
original
visit source
partner site
Fishbase

Importance

provided by Fishbase
fisheries: commercial; gamefish: yes
license
cc-by-nc
copyright
FishBase
Recorder
Kent E. Carpenter
original
visit source
partner site
Fishbase

Diagnostic Description

provided by Plazi (legacy text)

Records of the great white shark Carcharodon carcharias (Linnaeus) (Lamniformes: Lamnidae) in the Persian/Arabian Gulf (hereafter referred to as “The Gulf”) are limited to a single report from Kuwait, in the northwest Gulf, which has subsequently been noted in key references (e.g. Compagno, 2001). Khalaf (1987) recorded C. carcharias based on an observation of a mounted specimen in Kuwait Science and Natural History Museum on a visit there in March 1987. The specimen is reported as being a female C. carcharias of 3m in length, caught off Kuwait ’s coast and supplied to the museum on the 14th of April 1984. A black and white photograph of the anterior portion (from just posterior of the pelvic fins) was included in Khalaf’s account (Fig. 1 here), but no measurements or morphological data were presented.

The present authors examined the photograph and identified the specimen as Carcharias taurus Rafinesque (Lamniformes: Odontaspididae) based on the first dorsal fin origin being well behind the inner margins of the pectoral fins (cf. over the pectoral inner margins in C. carcharias ), the first dorsal fin insertion being about over the pelvic fin origin (cf. being well ahead of pelvic fin origin), a short flattened snout (cf. moderately long conical snout), moderately long gill openings not extending onto the dorsal surface (cf. long gill openings), and characteristic protruding teeth. The photograph presented did not allow for examination of the caudal region or for effective examination of colouration.

Carcharodon carcharias has been recorded from a wide range of habitats and with an extensive distribution ranging from the equatorial tropics to the sub-Arctic, and from the intertidal down to the continental slope (Compagno, 2001). Cliff et al. (2000), Compagno (2001), and Zuffa et al. (2002) report white sharks from the tropical Western Indian Ocean off Mozambique and Madagascar north to Tanzania and Kenya and including the Seychelles, Réunion and Mauritius. There is therefore no theoretical reason why this species should not occur in the Persian Gulf or the wider northwestern Indian Ocean, although the nearest confirmed record is from Sri Lanka and possibly the Red Sea (Compagno, 2001). In addition, there are unconfirmed, anecdotal records of white sharks from the Gulf of Aden coast of Yemen, Djibouti and northern Somalia (Conan Doyle, 1963).

Gubanov & Schleib (1980) reported C. taurus as sometimes being encountered in Kuwait waters, although Krupp et al., (2000) noted that there was no material provided to support this. Krupp et al., (2000) reported the first record of C. taurus from The Gulf supported by reference material based on a 2.98m specimen caught off Abu Halifa, Kuwait , in 1997. The C. taurus reported here predates this by thirteen years.

license
not applicable
bibliographic citation
Alec B. M. Moore, 2007, The Persian/Arabian Gulf's sole great white shark Carcharodon carcharias (Lamniformes: Lamnidae) record from Kuwait: misidentification of a sandtiger shark Carcharias taurus (Lamniformes: Odontaspididae)., Zootaxa, pp. 67-68, vol. 1591
author
Alec B. M. Moore
original
visit source
partner site
Plazi (legacy text)

分布

provided by The Fish Database of Taiwan
分布於除了東太平洋外的各溫暖海域。臺灣東部及東北部海域有分布。
license
cc-by-nc
copyright
臺灣魚類資料庫
author
臺灣魚類資料庫

利用

provided by The Fish Database of Taiwan
主要以底拖網、流刺網及延繩釣捕獲,經濟價值高。肉質佳,魚肉紅燒或加工成各種肉製品;鰭可做魚翅;皮厚可加工成皮革;肝可加工製成維他命及油;剩餘物製成魚粉。
license
cc-by-nc
copyright
臺灣魚類資料庫
author
臺灣魚類資料庫

描述

provided by The Fish Database of Taiwan
體呈紡錘型,軀幹較粗壯。頭寬扁,三角形。尾基上方具一凹窪;尾柄無側突。吻長而尖突。眼略小,卵圓形,無瞬膜。前鼻瓣短呈三角形;無口鼻溝或觸鬚。口裂寬,深弧形,下頜極短,口閉時露齒;頜齒大小不一,前面齒窄長而如鑽子狀,側面齒側扁如刀狀,往後則漸低小或退化如臼齒狀,齒具小齒尖或無。噴水孔非常山。背鰭2個,同型,第一背鰭中大,起點與胸鰭內角相對或稍後,後緣凹入,上角尖圓,下角微尖突;第二背鰭中大,僅略小於第一背鰭,起點與腹鰭後端相對,後緣深凹入,上角尖圓,下角微尖突;胸鰭寬大型,長寬約略等大,後緣微凹入,外角鈍圓,內角鈍圓,鰭端伸達不及第一背鰭基底前部;尾鰭寬長,尾椎軸稍上揚,上葉狹小,下葉前部顯著三角形突出,中部寬長,與後部間有一深缺刻,後部小三角形突出與上葉相連,尾端尖突,後緣凹入。體背側灰褐或黃褐色;腹側白色。體背面和鰭上具不規則紅褐色班點;鰭緣暗色。
license
cc-by-nc
copyright
臺灣魚類資料庫
author
臺灣魚類資料庫

棲地

provided by The Fish Database of Taiwan
棲息於沿岸由淺水激浪區至深達約90公尺處之近海。通常棲息於近底層,但亦會巡游於中層或水表層。游動時,能吞一口空氣於胃中,藉以調整浮力。具有洄游習性,春夏成群北上,秋冬遷移至南方。主要以硬骨魚類、小型鯊類、魟、烏賊、螃蟹或龍蝦為食。雖不具主動攻擊性,但仍對人
license
cc-by-nc
copyright
臺灣魚類資料庫
author
臺灣魚類資料庫

Sand tiger shark

provided by wikipedia EN

The sand tiger shark (Carcharias taurus), gray nurse shark, spotted ragged-tooth shark or blue-nurse sand tiger, is a species of shark that inhabits subtropical and temperate waters worldwide. It inhabits the continental shelf, from sandy shorelines (hence the name sand tiger shark) and submerged reefs to a depth of around 191 m (627 ft).[2] They dwell in the waters of Japan, Australia, South Africa, and the east coasts of North and South America. The sand tiger shark also inhabited the Mediterranean, however it was last seen there in 2003 and is presumed extinct in the region. Despite its common names, it is not closely related to either the tiger shark (Galeocerdo cuvier) or the nurse shark (Ginglymostoma cirratum).

Despite its fearsome appearance and strong swimming ability, it is a relatively placid and slow-moving shark with no confirmed human fatalities. This species has a sharp, pointy head, and a bulky body. The sand tiger's length can reach 3.2 m (10.5 ft) but is normally 2.2–2.5 m in length.[3] They are grey with reddish-brown spots on their backs. Shivers (groups) have been observed to hunt large schools of fish. Their diet consists of bony fish, crustaceans, squid, skates and other sharks. Unlike other sharks, the sand tiger can gulp air from the surface, allowing it to be suspended in the water column with minimal effort. During pregnancy, the most developed embryo will feed on its siblings, a reproductive strategy known as intrauterine cannibalism i.e. "embryophagy" or, more colorfully, adelphophagy—literally "eating one's brother". The sand tiger is categorized as critically endangered on the International Union for Conservation of Nature Red List. It is the most widely kept large shark in public aquariums owing to its tolerance for captivity.

Taxonomy

The sand tiger shark's description as Carcharias taurus by Constantine Rafinesque came from a specimen caught off the coast of Sicily. Carcharias taurus means "bull shark". This taxonomic classification has been long disputed. Twenty-seven years after Rafinesque's original description the German biologists Müller and Henle changed the genus name from C. taurus to Triglochis taurus. The following year, Swiss-American naturalist Jean Louis Rodolphe Agassiz reclassified the shark as Odontaspis cuspidata based on examples of fossilized teeth. Agassiz's name was used until 1961 when three palaeontologists and ichthyologists, W. Tucker, E. I. White, and N. B. Marshall, requested that the shark be returned to the genus Carcharias. This request was rejected and Odontaspis was approved by the International Code of Zoological Nomenclature (ICZN). When experts concluded that taurus belongs after Odontaspis, the name was changed to Odontaspis taurus. In 1977, Compagno and Follet challenged the Odontaspis taurus name and substituted Eugomphodus, a somewhat unknown classification, for Odontaspis. Many taxonomists questioned his change, arguing that there was no significant difference between Odontaspis and Carcharias. After changing the name to Eugomphodus taurus, Compagno successfully advocated in establishing the shark's current scientific name as Carcharias taurus. The ICZN approved this name, and today it is used among biologists.[2]

Common names

Because the sand tiger shark is worldwide in distribution, it has many common names. The term "sand tiger shark" actually refers to four different sand tiger shark species in the family Odontaspididae. Furthermore, the name creates confusion with the unrelated tiger shark Galeocerdo cuvier. The grey nurse shark, the name used in Australia, is the second-most used name for the shark, and in India it is known as blue-nurse sand tiger. However, there are unrelated nurse sharks in the family Ginglymostomatidae. The most unambiguous and descriptive English name is probably the South African one, spotted ragged-tooth shark.[2][4]

Identification

There are four species referred to as sand tiger sharks:[2]

  1. The sand tiger shark Carcharias taurus
  2. The Indian sand tiger shark Carcharias tricuspidatus. Very little is known about this species which, described before 1900, is probably the same as (a synonym of) the sand tiger C. taurus[2]
  3. The small-toothed sand tiger shark Odontaspis ferox. This species has a worldwide distribution, is seldom seen but normally inhabits deeper water than does C. taurus.
  4. The Big-eyed sand tiger shark Odontaspis noronhai, a deep water shark of the Americas, of which little is known.
Diagram indicating the differences between C. taurus and O. ferox

The most likely problem when identifying the sand tiger shark is when in the presence of either of the two species of Odontaspis. Firstly, the sand tiger is usually spotted, especially on the hind half of the body. However, there are several other differences that are probably more reliable:

  1. The bottom part of the caudal fin (tail fin) of the sand tiger is smaller.
  2. The second (i.e., hind) dorsal fin of the sand tiger is almost as large as the first (i.e., front) dorsal fin.
  3. The first (i.e., front) dorsal fin of the sand tiger is relatively non-symmetric.
  4. The first (i.e., front) dorsal fin of the sand tiger is closer to the pelvic fin than to the pectoral fin (i.e., the first dorsal fin is positioned further backwards in the case of the sand tiger).

Description

Adult sand tigers range from 2 m (6.6 ft) to 3.2 m (10.5 ft) in length with most specimens reaching a length of around 2.2–2.5 m and 91 kg (201 lb) to 159 kg (351 lb) in weight.[5] The head is pointy, as opposed to round, while the snout is flattened with a conical shape. Its body is stout and bulky and its mouth extends beyond the eyes. The eyes of the sand tiger shark are small, lacking eyelids.[2] A sand tiger usually swims with its mouth open displaying three rows of protruding, smooth-edged, sharp-pointed teeth.[6] The males have grey claspers with white tips located on the underside of their body. The caudal fin is elongated with a long upper lobe (i.e. strongly heterocercal). They have two large, broad-based grey dorsal fins set back beyond the pectoral fins.[2] The sand tiger shark has a grey-brown back and pale underside. Adults tend to have reddish-brown spots scattered, mostly on the hind part of the body.[6] In August 2007, an albino specimen was photographed off South West Rocks, Australia.[7] The teeth of these sharks have no transverse serrations (as have many other sharks) but they have a large, smooth main cusp with a tiny cusplet on each side of the main cusp.[2] The upper front teeth are separated from the teeth on the side of the mouth by small intermediate teeth.

Habitat and range

Geographical range

Sand tiger sharks roam the epipelagic and mesopelagic regions of the ocean,[8] sandy coastal waters, estuaries, shallow bays, and rocky or tropical reefs, at depths of up to 190 m (623 ft).

The sand tiger shark can be found in the Atlantic, Pacific and Indian Oceans, and in the Adriatic Seas. In the Western Atlantic Ocean, it is found in coastal waters around from the Gulf of Maine to Florida, in the northern Gulf of Mexico, around the Bahamas and Bermuda, and from southern Brazil to northern Argentina. It is also found in the eastern Atlantic Ocean from the Mediterranean Sea to the Canary Islands, at the Cape Verde islands, along the coasts of Senegal and Ghana, and from southern Nigeria to Cameroon. In the western Indian Ocean, the shark ranges from South Africa to southern Mozambique, but excluding Madagascar. The sand tiger shark has also been sighted in the Red Sea and may be found as far east as India. In the western Pacific, it has been sighted in the waters around the coasts of Japan and Australia, but not around New Zealand.[1]

Annual movements of sand tiger sharks off South Africa and Australia

Annual migration

Sand tigers in South Africa and Australia undertake an annual migration that may cover more than 1,000 km (620 mi).[8] They pup during the summer in relatively cold water (temperature ca. 16 °C [61 °F]). After parturition, they swim northwards toward sites where there are suitable rocks or caves, often at a water depth ca. 20 m (66 ft), where they mate during and just after the winter.[9] Mating normally takes place at night. After mating, they swim further north to even warmer water where gestation takes place. In the Autumn they return southwards to give birth in cooler water. This round trip may encompass as much as 3,000 km (1,900 mi). The young sharks do not take part in this migration, but they are absent from the normal birth grounds during winter: it is thought that they move deeper into the ocean.[8] At Cape Cod (USA), juveniles move away from coastal areas when water temperatures decreases below 16 °C and day length decreases to less than 12 h.[10] Juveniles, however, return to their usual summer haunts and as they become mature they start larger migratory movements.

Behavior

Hunting

The sand tiger shark is a nocturnal feeder. During the day, they take shelter near rocks, overhangs, caves and reefs often at relatively shallow depths (<20 m). This is the typical environment where divers encounter sand tigers, hovering just above the bottom in large sandy gutters and caves.[11] However, at night they leave the shelter and hunt over the ocean bottom, often ranging far from their shelter.[12] Sand tigers hunt by stealth. It is the only shark known to gulp air and store it in the stomach, allowing the shark to maintain near-neutral buoyancy which helps it to hunt motionlessly and quietly.[2] Aquarium observations indicate that when it comes close enough to a prey item, it grabs with a quick sideways snap of the prey. The sand tiger shark has been observed to gather in hunting groups when preying upon large schools of fish.[2]

Diet

A bottom-living smooth-hound shark, one of the important prey items of sand tiger sharks

The majority of prey items of sand tigers are demersal (i.e. from the sea bottom), suggesting that they hunt extensively on the sea bottom as far out as the continental shelf. Bony fish (teleosts) form about 60% of sand tigers' food, the remaining prey comprising sharks, skates, other rays, lobsters, crabs and squid.[13] In Argentina, the prey includes mostly demersal fishes, e.g. the striped weakfish (Cynoscion guatucupa) and whitemouth croaker (Micropogonias furnieri). The most important elasmobranch prey is the bottom-living narrownose smooth-hound shark (Mustelus schmitti.). Benthic (i.e. free-swimming) rays and skates are also taken, including fanskates, eagle rays and the angular angel shark, with larger individuals feeding on a higher number of benthic elasmobranchs than smaller individuals.[14] Stomach content analysis indicates that smaller sand tigers mainly focus on the sea bottom and as they grow larger they start to take more benthic prey. This perspective of the diet of sand tigers is consistent with similar observations in the north west Atlantic[15] and in South Africa where large sand tigers capture a wider range of shark and skate species as prey, from the surf zone to the continental shelf, indicating the opportunistic nature of sand tiger feeding.[12] Off South Africa, sand tigers less than 2 m (6.6 ft) in length prey on fish about a quarter of their own length; however, large sand tigers capture prey up to about half of their own length.[12] The prey items are usually swallowed as three or four chunks.[14]

Courtship and mating

Mating occurs around the months of August and December in the northern hemisphere and during August–October in the southern hemisphere. The courtship and mating of sand tigers has been best documented from observations in large aquaria. In Oceanworld, Sydney, the females tended to hover just above the sandy bottom ("shielding") when they were receptive.[16] This prevented males from approaching from underneath towards their cloaca. Often there is more than one male close by with the dominant one remaining close to the female, intimidating others with an aggressive display in which the dominant shark closely follows the tail of the subordinate, forcing the subordinate to accelerate and swim away. The dominant male snaps at smaller fish of other species. The male approaches the female and the two sharks protect the sandy bottom over which they interact. Strong interest of the male is indicated by superficial bites in the anal and pectoral fin areas of the female. The female responds with superficial biting of the male. This behaviour continues for several days during which the male patrols the area around the female. The male regularly approaches the female in "nosing" behaviour to "smell" the cloaca of the female. If she is ready, she swims off with the male, while both partners contort their bodies so that the right clasper of the male enters the cloaca of the female. The male bites the base of her right pectoral fin, leaving scars that are easily visible afterwards. After one or two minutes, mating is complete and the two separate. Females often mate with more than one male.[17] Females mate only every second or third year.[18] After mating, the females remain behind, while the males move off to seek other areas to feed,[18] resulting in many observations of sand tiger populations comprising almost exclusively females.

Reproduction and growth

Growth curve for sand tiger sharks in the north Atlantic

Reproduction

The reproductive pattern is similar to that of many of the Lamnidae, the shark family to which sand tigers belong. Female sand tigers have two uterine horns that, during early embryonic development, may have as many as 50 embryos that obtain nutrients from their yolk sacs and possibly consume uterine fluids. When one of the embryos reaches some 10 cm (4 in) in length, it eats all the smaller embryos so that only one large embryo remains in each uterine horn, a process called intrauterine cannibalism i.e. "embryophagy" or, more colorfully, adelphophagy—literally "eating one's brother."[2][17] While multiple male sand tigers commonly fertilize a single female, adelphophagy sometimes excludes all but one of them from gaining offspring. These surviving embryos continue to feed on a steady supply of unfertilised eggs.[19] After a lengthy labour, the female gives birth to 1 m (3.3 ft) long, fully independent offspring. The gestation period is approximately eight to twelve months. These sharks give birth only every second or third year,[18] resulting in an overall mean reproductive rate of less than one pup per year, one of the lowest reproductive rates for sharks.

Growth

In the north Atlantic, sand tiger sharks are born about 1 m in length. During the first year, they grow about 27 cm to reach 1.3 m. After that, the growth rate decreases by about 2.5 cm each year until it stabilises at about 7 cm/y.[20] Males reach sexual maturity at an age of five to seven years and approximately 1.9 m (6.2 ft) in length. Females reach maturity when approximately 2.2 m (7.2 ft) long at about seven to ten years of age.[20] They are normally not expected to reach lengths over 3 m and lengths around 2.2–2.5 is more common. In the informal media, such as YouTube, there have been several reports of sand tigers around 5 m long, but none of these have been verified scientifically.

Interaction with humans

Attacks on humans

The sand tiger is often wrongly associated with being vicious or deadly, due to its relatively large size and sharp, protruding teeth that point outward from its jaws; however, these sharks are quite docile, and are not a threat to humans. Their mouths are not large enough to cause a human fatality. Sand tigers roam the surf, sometimes in close proximity to humans, and there have been only a few instances of unprovoked sand tiger shark attacks on humans, usually associated with spear fishing, line fishing, or shark feeding.[5] As of 2013, the database of Shark Attack Survivors does not list any fatalities due to sand tiger sharks.[21] When the sharks become aggressive, they tend to steal fish or bait from fishing lines rather than attack humans. Owing to its large size and docile temperament, the sand tiger is commonly displayed in aquariums around the world.[5]

Nets around swimming beaches

In Australia and South Africa, one of the common practices in beach holiday areas is to erect shark nets around the beaches frequently used by swimmers. These nets are erected some 400 m (1,300 ft) from the shore and act as gill nets that trap incoming sharks:[22] this was the norm until about 2005. In South Africa, the mortality of sand tiger sharks caused a significant decrease in the length of these animals and it was concluded that the shark nets pose a significant threat to this species with its very low reproductive rate[23] Before 2000, these nets snagged about 200 sand tiger sharks per year in South Africa, of which only about 40% survived and were released alive.[24] The efficiency of shark nets for the prevention of unprovoked shark attacks on bathers has been questioned, and since 2000 there has been a reduced use of these nets and alternative approaches are being developed.

Sand tiger shark in the Newport Aquarium

Competition for food with humans

In Argentina, the prey items of sand tigers largely coincided with important commercial fisheries targets.[14] Humans affect sand tiger food availability and the sharks, in turn, compete with humans for food that, in turn, has already been heavily exploited by the fisheries industry. The same applies to the bottom-living sea catfish (Galeichthys feliceps), a fisheries resource off the South African coast.[12]

Effects of scuba divers

Sand tiger sharks are often the targets of scuba divers who wish to observe or photograph these animals. A study near Sydney in Australia found that the behaviour of the sharks is affected by the proximity of scuba divers.[25] Diver activity affects the aggregation, swimming and respiratory behaviour of sharks, but only at short time scales. The group size of scuba divers was less important in affecting sand tiger behaviour than the distance within which they approached the sharks. Divers approaching to within 3 m of sharks affected their behaviour but after the divers had retreated, the sharks resumed normal behaviour. Other studies indicate sand tiger sharks can be indifferent to divers.[26] Scuba divers are normally compliant with Australian shark-diving regulations.[27]

In captivity

Its large and menacing appearance, combined with its relative placidity, has made the sand tiger shark among the most popular shark species to be displayed in public aquaria.[28] However, as with all large sharks, keeping them in captivity is not without its difficulties. Sand tiger sharks have been found to be highly susceptible to developing spinal deformities, with as many as one in every three captive sharks being affected, giving them a hunched appearance.[29] These deformities have been hypothesized to be correlated to both the size and shape of their tank.[30] If the tank is too small, the sharks have to spend more time actively swimming than they would in the wild, where they have space to glide. Also, sharks in small, circular tanks often spend most of their time circling along the edges in only one direction, causing asymmetrical stress on their bodies.

Threats and conservation status

Threats

There are several factors contributing to the decline in the population of the sand tigers. Sand tigers reproduce at an unusually low rate, due to the fact that they do not have more than two pups at a time and because they breed only every second or third year. This shark is a highly prized food item in the western northern Pacific, off Ghana and off India and Pakistan where they are caught by fishing trawlers, although they are more commonly caught with a fishing line.[2] Sand tigers' fins are a popular trade item in Japan.[1] Off North America, it is fished for its hide and fins. Shark liver oil is a popular product in cosmetic products such as lipstick.[6] It is sought by anglers in fishing competitions in South Africa and some other countries. In Australia it has been reduced in numbers by spear fishers using poison and where it is now protected.[2] It is also prized as an aquarium exhibit in the United States, Europe, Australia and South Africa because of its docile and hardy nature.[2] Thus, overfishing is a major contributor to the population decline. All indications show that the world population in sand tigers has been reduced significantly in size since 1980.[2] Many sand tigers are caught in shark nets, and then either strangled or taken by fishermen.[1] Estuaries along the United States of America's eastern Atlantic coast houses many of the young sand tiger sharks. These estuaries are susceptible to non-point source pollution that is harmful to the pups.[6] In Eastern Australia, the breeding population was estimated to be fewer than 400 reproductively mature animals, a number believed to be too small to sustain a healthy population.[31]

Conservation status

This species is therefore listed as Critically Endangered on the International Union for Conservation of Nature Red List,[1] and as endangered under Queensland's Nature Conservation Act 1992. It is a U.S. National Marine Fisheries Service [Species of Concern], which are those species that the U.S. Government's National Oceanic and Atmospheric Administration, National Marine Fisheries Service (NMFS), has some concerns regarding status and threats, but for which insufficient information is available to indicate a need to list the species under the U.S. Endangered Species Act. According to the National Marine Fisheries Service, any shark caught must be released immediately with minimal harm, and is considered a prohibited species, making it illegal to harvest any part of the sand tiger shark on the United States' Atlantic coast.[6]

A recent report from the Pew Charitable Trusts suggests that a new management approach used for large mammals that have suffered population declines could hold promise for sharks. Because of the life-history characteristics of sharks, conventional fisheries management approaches, such as reaching maximum sustainable yield, may not be sufficient to rebuild depleted shark populations. Some of the more stringent approaches used to reverse declines in large mammals may be appropriate for sharks, including prohibitions on the retention of the most vulnerable species and regulation of international trade.[32]

References

  1. ^ a b c d e Rigby, C.L.; Carlson, J.; Derrick, D.; Dicken, M.; Pacoureau, N.; Simpfendorfer, C. (2021). "Carcharias taurus". IUCN Red List of Threatened Species. 2021. Retrieved 26 September 2021.
  2. ^ a b c d e f g h i j k l m n o Compagno, L. J. V. (1984). Vol.4. Sharks of the World: An annotated and illustrated catalogue of shark species known to date; Part 1 - Hexanchiformes to Lamniformes. FAO Species Catalogue. Rome: Food and Agriculture Organization. ISBN 92-5-101384-5.
  3. ^ "Carcharias taurus: Sandtiger Shark". Florida Museum of Natural History. 18 October 2018. Retrieved 6 May 2019.
  4. ^ "Common names of Carcharias taurus". FishBase. Retrieved 4 December 2011.
  5. ^ a b c "Sand Tiger Shark". National Geographic Society. 2009. Retrieved 26 October 2011.
  6. ^ a b c d e "Sand tiger shark" (PDF). NOAA National Marine Fisheries Service. 2011. Retrieved November 28, 2011.
  7. ^ Williams, Samantha (8 August 2007). "Rare albino shark rules deep". The Daily Telegraph. Sydney. Archived from the original on 7 February 2009.
  8. ^ a b c Dicken, M. L.; Booth, A. J.; Smale, M. J.; Cliff, G. (2007). "Spatial and seasonal distribution patterns of juvenile and adult raggedtooth sharks (Carcharias taurus) tagged off the east coast of South Africa". Marine and Freshwater Research. 58: 127. doi:10.1071/MF06018.
  9. ^ Bansemer, C. S.; Bennett, M. B. (2011). "Sex- and maturity-based differences in movement and migration patterns of grey nurse shark, Carcharias taurus, along the eastern coast of Australia". Marine and Freshwater Research. 62 (6): 596. doi:10.1071/MF10152.
  10. ^ Kneebone, J.; Chisholm, J.; Skomal, G. B. (2012). "Seasonal residency, habitat use, and site fidelity of juvenile sand tiger sharks Carcharias taurus in a Massachusetts estuary". Marine Ecology Progress Series. 471: 165–181. Bibcode:2012MEPS..471..165K. doi:10.3354/meps09989.
  11. ^ Bray, Dianne J. (2014). "Carcharias taurus". Fishes of Australia. Retrieved 26 August 2014.
  12. ^ a b c d Smale, M. J. (2005). "The diet of the ragged-tooth shark Carcharias taurus Rafinesque 1810 in the Eastern Cape, South Africa" (PDF). African Journal of Marine Science. 27: 331–335. doi:10.2989/18142320509504091. S2CID 84782633. Archived from the original (PDF) on 2 April 2012. Retrieved 10 September 2011.
  13. ^ "Carcharias taurus (Dogfish shark)". Animal Diversity Web.
  14. ^ a b c Lucifora, L. O.; García, V. B.; Escalante, A. H. (2009). "How can the feeding habits of the sand tiger shark influence the success of conservation programs?". Animal Conservation. 12 (4): 291. doi:10.1111/j.1469-1795.2009.00247.x. S2CID 52239125.
  15. ^ Gelsleichter, J.; Musick, J. A.; Nichols, S. (1999). "Food habits of the smooth dogfish, Mustelus canis, dusky shark, Carcharhinus obscurus, Atlantic sharpnose shark, Rhizoprionodon terraenovae, and the sand tiger, Carcharias taurus, from the northwest Atlantic Ocean". Environmental Biology of Fishes. 54 (2): 205. doi:10.1023/A:1007527111292. S2CID 21850377.
  16. ^ Gordon, I. (1993). "Pre-copulatory behaviour of captive sandtiger sharks, Carcharias taurus". Environmental Biology of Fishes. 38 (1–3): 159–164. doi:10.1007/BF00842912. S2CID 25874513.
  17. ^ a b Chapman, D. D.; Wintner, S. P.; Abercrombie, D. L.; Ashe, J.; Bernard, A. M.; Shivji, M. S.; Feldheim, K. A. (2013). "The behavioural and genetic mating system of the sand tiger shark, Carcharias taurus, an intrauterine cannibal". Biology Letters. 9 (3): 20130003. doi:10.1098/rsbl.2013.0003. PMC 3645029. PMID 23637391.
  18. ^ a b c Bansemer, C. S.; Bennett, M. B. (2009). "Reproductive periodicity, localised movements and behavioural segregation of pregnant Carcharias taurus at Wolf Rock, southeast Queensland, Australia". Marine Ecology Progress Series. 374: 215–227. Bibcode:2009MEPS..374..215B. doi:10.3354/meps07741.
  19. ^ Gilmore, R.G.; Dodrill, J.W. & Linley, P. (1983). "Reproduction and embryonic development of the sand tiger shark, Odontaspis taurus (Rafinesque)" (PDF). Fishery Bulletin. 81 (2): 201–225.
  20. ^ a b Branstetter, Steven; Musick, John A. (1994). "Age and Growth Estimates for the Sand Tiger in the Northwestern Atlantic Ocean". Transactions of the American Fisheries Society. 123 (2): 242. doi:10.1577/1548-8659(1994)123<0242:AAGEFT>2.3.CO;2.
  21. ^ "Species Search". Shark Attack Survivors. Archived from the original on 3 May 2013.
  22. ^ Dudley, S. F. J. (1997). "A comparison of the shark control programs of New South Wales and Queensland (Australia) and KwaZulu-Natal (South Africa)". Ocean & Coastal Management. 34: 1–9. doi:10.1016/S0964-5691(96)00061-0.
  23. ^ Dudley, S. F. J.; Simpfendorfer, C. A. (2006). "Population status of 14 shark species caught in the protective gillnets off KwaZulu–Natal beaches, South Africa, 1978–2003". Marine and Freshwater Research. 57 (2): 225. doi:10.1071/MF05156.
  24. ^ Brazier, W.; Nel, R.; Cliff, G.; Dudley, S. (2012). "Impact of protective shark nets on sea turtles in KwaZulu-Natal, South Africa, 1981–2008". African Journal of Marine Science. 34 (2): 249. doi:10.2989/1814232X.2012.709967. S2CID 84770491.
  25. ^ Barker, S. M.; Peddemors, V. M.; Williamson, J. E. (2011). "A video and photographic study of aggregation, swimming and respiratory behaviour changes in the Grey Nurse Shark (Carcharias taurus) in response to the presence of SCUBA divers". Marine and Freshwater Behaviour and Physiology. 44 (2): 75. doi:10.1080/10236244.2011.569991. S2CID 54763603.
  26. ^ Viegas, Jennifer (9 July 2014). "Sand Tiger Sharks Are Curious About People". Discovery Channel. Archived from the original on 4 April 2017. Retrieved 17 June 2015.
  27. ^ Smith, K.; Scarr, M.; Scarpaci, C. (2010). "Grey Nurse Shark (Carcharias taurus) Diving Tourism: Tourist Compliance and Shark Behaviour at Fish Rock, Australia". Environmental Management. 46 (5): 699–710. Bibcode:2010EnMan..46..699S. doi:10.1007/s00267-010-9561-8. PMID 20872140. S2CID 26245645.
  28. ^ "Sand Tiger Shark". National Geographic. Retrieved 6 May 2019.
  29. ^ "A Mystery in Captivity". The Campus. 26 October 2012. Retrieved 6 May 2019.
  30. ^ Tate, Erin E. (2013). "Correlations of Swimming Patterns with Spinal Deformities in the Sand Tiger Shark, Carcharias taurus" (PDF). International Journal of Comparative Psychology. 26: 75–82. doi:10.46867/ijcp.2013.26.01.03. Archived from the original (PDF) on 27 September 2013.
  31. ^ "Critically endangered grey nurse shark mapped for the first time in landmark study". Macquarie University. 5 February 2019. Retrieved 6 May 2019.
  32. ^ "Considering Shark Biology in Management". The Pew Charitable Trusts. 2 July 2015. Retrieved 5 July 2015.
license
cc-by-sa-3.0
copyright
Wikipedia authors and editors
original
visit source
partner site
wikipedia EN

Sand tiger shark: Brief Summary

provided by wikipedia EN

The sand tiger shark (Carcharias taurus), gray nurse shark, spotted ragged-tooth shark or blue-nurse sand tiger, is a species of shark that inhabits subtropical and temperate waters worldwide. It inhabits the continental shelf, from sandy shorelines (hence the name sand tiger shark) and submerged reefs to a depth of around 191 m (627 ft). They dwell in the waters of Japan, Australia, South Africa, and the east coasts of North and South America. The sand tiger shark also inhabited the Mediterranean, however it was last seen there in 2003 and is presumed extinct in the region. Despite its common names, it is not closely related to either the tiger shark (Galeocerdo cuvier) or the nurse shark (Ginglymostoma cirratum).

Despite its fearsome appearance and strong swimming ability, it is a relatively placid and slow-moving shark with no confirmed human fatalities. This species has a sharp, pointy head, and a bulky body. The sand tiger's length can reach 3.2 m (10.5 ft) but is normally 2.2–2.5 m in length. They are grey with reddish-brown spots on their backs. Shivers (groups) have been observed to hunt large schools of fish. Their diet consists of bony fish, crustaceans, squid, skates and other sharks. Unlike other sharks, the sand tiger can gulp air from the surface, allowing it to be suspended in the water column with minimal effort. During pregnancy, the most developed embryo will feed on its siblings, a reproductive strategy known as intrauterine cannibalism i.e. "embryophagy" or, more colorfully, adelphophagy—literally "eating one's brother". The sand tiger is categorized as critically endangered on the International Union for Conservation of Nature Red List. It is the most widely kept large shark in public aquariums owing to its tolerance for captivity.

license
cc-by-sa-3.0
copyright
Wikipedia authors and editors
original
visit source
partner site
wikipedia EN

Description

provided by World Register of Marine Species
Lives mostly on or near the bottom, from the surf zone, in shallow bays, and around coral and rocky reefs down to at least 191 m depth on the outer shelves (Ref. 247). Migratory species which feeds on small fish, sharks, rays, squids, and on crabs and lobsters occasionally (Ref. 5213). Maybe solitary or forms small to large schools. Reproduction features ovophagy or uterine cannibalism. Only one of 16-23 egg cases survives. Inoffensive and unaggresive when not provoked (Ref. 247).

Reference

Froese, R. & D. Pauly (Editors). (2023). FishBase. World Wide Web electronic publication. version (02/2023).

license
cc-by-4.0
copyright
WoRMS Editorial Board
contributor
Edward Vanden Berghe [email]

Diet

provided by World Register of Marine Species
Feeds on bony fishes, small sharks, rays, squids, crabs and lobsters

Reference

North-West Atlantic Ocean species (NWARMS)

license
cc-by-4.0
copyright
WoRMS Editorial Board
contributor
Kennedy, Mary [email]

Diet

provided by World Register of Marine Species
feeds on a wide variety of bony fishes (teleosts), with elasmobranchs an important secondary prey; crustaceans, cephalopods, and marine mammals are also taken. Bony fish prey includes herring (Clupeidae), anchovies (Engraulidae), hake (Merluccidae), eels (Anguillidae), monkfish or anglers (Lophiidae), cusk eels (Ophidiidae), lizardfish (Synodontidae), sea catfish (Ariidae), croakers (Sciaenidae), Australian salmon (Arripidae), morwong (Cheilodactylidae), rock blackfish or opaleyes (Girellidae), bluefish, elf or taylor (Pomatomidae), mackerel and bonito (Scombridae),butterfishes (Stromateidae), snappers (Lutjanidae), wrasses (Labridae), mullet (Mugilidae), spadefish (Chaetodipteridae), sea robins (Triglidae), flatheads (Platycephalidae), duckbills (Percophidae), midshipmen (Batrachodidae), sea basses(Serranidae), porgies or sea bream (Sparidae), jacks (Carangidae), remoras (Echeneidae), flatfish (Pleuronectiformes) including soles (Soleidae), American soles (Achiridae), Atlantic flounders (Scophthalmidae), and righteye flounders (Paralichthyidae), and undoubtedly many others. Elasmobranch prey includes requiem sharks (Carcharhinidae), houndsharks (Triakidae), angel sharks (Squatinidae), skates (Rajidae) and their egg cases, and eagle rays (Aetobatus and Myliobatis, Myliobatidae). Invertebrate prey includes squid (Loliginidae), crabs, lobsters and hermit crabs (Paguridae). Plant material is rarely found in stomach contents, and presumably is accidentally ingested along with animal prey.

Reference

Compagno, L.J.V. (2001). Sharks of the world. An annotated and illustrated catalogue of shark species known to date. Volume 2. Bullhead, mackerel and carpet sharks (Heterodontiformes, Lamniformes and Orectolobiformes). FAO Species Catalogue for Fishery Purposes. No. 1, Vol. 2. Rome, FAO. 269p.

license
cc-by-4.0
copyright
WoRMS Editorial Board
contributor
Elien Dewitte [email]

Distribution

provided by World Register of Marine Species
Gulf of Maine to Argentina

Reference

North-West Atlantic Ocean species (NWARMS)

license
cc-by-4.0
copyright
WoRMS Editorial Board
contributor
Kennedy, Mary [email]

Habitat

provided by World Register of Marine Species
Found at depths of 0-191 m, often on or near the bottom.

Reference

North-West Atlantic Ocean species (NWARMS)

license
cc-by-4.0
copyright
WoRMS Editorial Board
contributor
Kennedy, Mary [email]

Habitat

provided by World Register of Marine Species
benthic

Reference

North-West Atlantic Ocean species (NWARMS)

license
cc-by-4.0
copyright
WoRMS Editorial Board
contributor
Kennedy, Mary [email]

Habitat

provided by World Register of Marine Species
An inshore and offshore, littoral shark. This shark occurs in the surf zone off sandy and rocky beaches, in shallow bays, on offshore banks and reefs, in underwater caves, in troughs on sandy areas, and around coral and rocky reefs from the intertidal less than 1mdeep down to at least 191 m, with most at depths of 15 to 25 m. This species is often found near or on the bottom but also occurs in midwater or at the surface.

Reference

Compagno, L.J.V. (2001). Sharks of the world. An annotated and illustrated catalogue of shark species known to date. Volume 2. Bullhead, mackerel and carpet sharks (Heterodontiformes, Lamniformes and Orectolobiformes). FAO Species Catalogue for Fishery Purposes. No. 1, Vol. 2. Rome, FAO. 269p.

license
cc-by-4.0
copyright
WoRMS Editorial Board
contributor
Elien Dewitte [email]