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Ginglymostoma cirratum:   (click for more)

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Synonyms
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  • Squalus punctulatus  Lacépède, 1800: 119, pl. 4, fig. 3. Type locality: "Guiane". No types known according to Eschmeyer (1998: CD-ROM).
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  • Squalus cirrhatus  Bloch and Schneider, 1801: 128. Based on S. cirratus Gmelin, in Linnaeus and Gmelin, 1788, possibly an emended or erroneous spelling.
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  • Ginglymostoma cirrhatum  Jordan, 1905: 533.
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  • Squalus punctatus  Bloch and Schneider, 1801: 134. Based on the "Gata" of Parra, 1787: 86, pl. 34, fig. 2, from Cuba. No types known according to Eschmeyer (1998: CD-ROM).
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  • Scyllium cirrhosum  Griffith and Smith, 1834, in Cuvier Griffith and Smith, : 10, pl. 30. Variant spelling?
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  • Ginglymostoma cirrosum  "Müller and Henle", 1838, in Bonaparte, : 213. Variant spelling.
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  • Squalus argus  Bancroft, 1832: 82. Holotype possibly in British Museum (Natural History) according to Eschmeyer (1998: CD-ROM), who indicates that this species was not characterized in the original account, but was described in an accompanying account by Bennett (1832: 86-91). Type locality:West Indies.
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  • Ginglymostoma fulvum  Poey, 1858: 342; also Poey, 1860, pl. 19, figs. 15-16. Holotype: 839 mm female, Cuba. Paepke and Schmidt (1988: 162) list Institut für Spezielle Zoologie und Zoologisches Museum, Berlin, ZMB-5508, 965 mm TL specimen, as a possible syntype.
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  • Ginglymostoma caboverdianus  Capello, 1867: 167. Cape Verde. Three syntypes according to Eschmeyer (1998: CD-ROM), but status of these types otherwise uncertain.
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  • Ginglymostoma cirrotum  Gudger, 1914: 176. Erroneous spelling?
    Other Combinations:   (Bonnaterre, 1788),
    FAO Names
    En - Nurse shark, Fr - Requin-nourrice, Sp - Gata nodriza.
    3Alpha Code: GNC     Taxonomic Code: 1070300901
    Scientific Name with Original Description
    Squalus cirratus  Bonnaterre, 1788, Tabl. Encyclop. Method. Trois Reg. Nat., Ichthyol., Paris: 7. Lectotype: Museum National d'Histoire Naturelle, Paris, MNHN-A.7654, 458 mm immature female, "Les mers de la Amerique." From unpublished addendum to Bertin (1939b, Bull. Mus. Nat. Hist. Nat., 2e ser., 12(6): 51-98) by M.L. Bauchot (pers. comm.), also Eschmeyer (1998, Cat. Fish.: CD-ROM). Separately described as Squalus cirratus Gmelin, in Linnaeus and Gmelin, 1788, Syst. Nat., ed. 13, Pisces 1(3): 1492. Types?
    Diagnostic Features
    fieldmarks: Moderately long barbels, nasoral grooves present but no circumnarial grooves; eyes dorsolateral, mouth well in front of eyes, spiracles minute; precaudal tail shorter than head and body; two spineless, broadly rounded, dorsal fins and an anal fin, first dorsal fin much larger than second dorsal and anal fins, caudal fin moderately long, over one-fourth of total length; colour yellow-brown to grey-brown, young with small dark, light-ringed ocellar spots and obscure dorsal saddle markings, adults and subadults without spots or saddles.

    Head in dorsal or ventral view broadly arcuate in young, narrower and U-shaped in adults. Snout bluntly wedge-shaped in lateral view, short and with mouth width about 2.3 to 2.6 times preoral length. Eyes small but usually over 1% of total length, positioned dorsolateral on head and with strong subocular ridges below them. Eyes with ventral edges just above level of dorsal ends of gill slits.  Gill openings dorsolaterally situated on head and not or hardly visible from below but just reaching horizontal head rim in dorsal view.  Nostrils nearly terminal on snout. Nasal barbels moderately elongated, tapered, slender and over 1% of total length, reaching past mouth. Lower lip trilobate and divided by shallow orolabial grooves connecting mouth with lower labial furrows. Distance between lower labial furrows about 1.5 times their length.  Tooth rows 30 to 42/28 to 34, functional tooth series at least 7 to 9/8 to 12. Teeth moderately compressed, not imbricated but in alternate overlap pattern, functional series not separated from replacement series by toothless space. Tooth crown feet broad, cusps moderately tall, cusplets moderately large and 2 to 6 on each side, basal ledges moderately broad. Teeth osteodont, with pulp cavity filled by osteodentine.  Body semifusiform.  Lateral trunk denticles broad and rhomboid in adults, with three strong parallel ridges and a very short, blunt cusp.  Pectoral fins broad and rounded-angular in young and semifalcate in large specimens, apices rounded. Pectoral-fin origins slightly behind to slightly in front of third gill slits. Pectoral fins plesodic and with radials reaching about 80% into fin web, radial segments 7 or 8 in longest radials. Pelvic fins rounded in young, possibly subangular in adults. Dorsal fins apically rounded. First dorsal-fin origin about over, slightly in front, or slightly behind pelvic-fin origins. Second dorsal fin distinctly smaller than first dorsal fin. Anal fin distinctly smaller than second dorsal fin, apically rounded. Anal-fin origin about opposite, slightly behind, or slightly in front of midbase of second dorsal-fin, with apex about under anal-fin base and posterior margin extending behind level of lower caudal-fin origin. Caudal fin long with dorsal caudal-fin margin over 25% of total length (adults). Caudal fin narrow and shallow with dorsal caudal-fin margin 3.2 to 3.6 times caudal-fin depth; no ventral caudal-fin lobe in young but a weak one in adults; preventral caudal-fin margin much shorter than postventral margin and 43 to 67% of it; terminal lobe short and 15 to 19% of dorsal caudal-fin margin.  Total vertebral count 168 to 175, monospondylous precaudal count 48 to 50, diplospondylous caudal count 73 to 83 and 43 to 48% of total count. Jaws broadly arcuate. Intestinal valve count 16 to 17.  Yellowish to grey-brown above and light whitish brown below, young with small dark, light-ringed ocellar spots and obscure dorsal saddle markings, adults and subadults without spots or saddles. 
    Geographical Distribution

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    Western Atlantic: Rhode Island to southern Brazil, including United States (exceptionally Rhode Island and North Carolina, South Georgia and Florida and Gulf coast from Florida to Texas), Mexico (Gulf of Mexico and Caribbean coasts), Bermuda, Bahamas, Turks and Caicos Islands, Cuba, Puerto Rico, Haiti, the Lesser Antilles, Belize, Jamaica, Barbados, Trinidad, French Guiana, Guyana, Panama, and Brazil (south to Rio de Janeiro). Eastern Atlantic: Cape Verde Islands, Senegal, Cameroon to Gabon, and rarely north to Gulf of Gascony, France. Eastern Pacific: Mexico (Baja California Sur, Gulf of California) south to Costa Rica, Panama, Ecuador, and Peru. The known distribution of the nurse shark suggests at least three geographically isolated populations (eastern Pacific, western Atlantic and eastern Atlantic), but their differentiation, if any, has yet to be studied.
    Habitat and Biology
    This is an inshore bottom shark of the continental and insular shelves in tropical and subtropical waters,often occurring at depths of 1 m or less in the intertidal, but down to at least 12 m and off Brazil between 40 and 130 m. The nurse shark is often found on rocky and coral reefs, in channels between mangrove keys and on sand flats.

    This is a large nocturnal and facultatively social shark that is proverbially sluggish during the daytime but strong-swimming and active at night; it rests on sandy bottom or in caves and crevices in rocks and coral reefs in shallow water during the day, often in schools or aggregates of three to three dozen individuals that are close to, or even piled on one another while resting. Swimming speed was measured at 31 to 78 cm/sec for a 250 cm captive individual (Hussain, 1991). In addition to swimming near the bottom or well off it, the nurse shark can clamber on the bottom using its flexible, muscular pectoral fins as limbs. Preliminary studies suggest that the nurse shark shows a strong preference for certain day-resting sites, and repeatedly homes back to the same caves and crevices after a night's activity. Nurse sharks fitted with conventional and sonic tags show little if any local movement, but adults have a larger range than young (Carrier, 1990). This suggests that groups of these animals are site-localized and vulnerable to local extirpation from overexploitation. This shark has been historically common or abundant in some areas where it occurs, particularly in the tropical western North Atlantic and off Tropical West Africa.

    Courtship and copulatory behaviour has been observed in captivity (Klimley, 1980) and studied in detail in the wild (Carrier, Pratt and Martin, 1994), and is apparently rather complex. In captivity a pair or sometimes a triplet of adults engage in synchronized parallel swimming, with the male abreast or slightly behind and below the female, but with sides nearly touching. A pair may rest on the bottom on their bellies in parallel after bouts of parallel swimming. While parallel-swimming, the male may grab one of the female's pectoral fins with his mouth, which in turn may induce the female to pivot 90° and roll on her back on the bottom. The male then nudges the female into a position parallel to him, swims on top of the female in parallel, inserts a single clasper in her vent, and then rolls on his back to lie motionless besides the inverted female with clasper still inserted. Carrier, Pratt and Martin divided nurse shark mating into five stages based on field observations of free-ranging individuals in a mating area in the Dry Tortugas, Florida: Precoupling, in which a male or group of males approached a female that was resting or swimming, in the latter case with parallel or tandem swimming, and with males approaching alongside and slightly behind the female with heads close to her pectoral fins. Coupling, in which the male grabs the female's pectoral fin, sometimes with two males grabbing both pectoral fins and with other males circling in close proximity. Positioning, in which the male, or two males, roll the female onto her back, and with the male rolling and aligning his tail and pelvic fins prior to copulation. Insertion and copulation, in which the male copulates with the female, inserting his right clasper if holding her right pectoral, and his left clasper if holding her left pectoral, and thrusts against the female who remains quiescent. Postcopulation, in which the male removes his claspers, releases the female's pectoral, and either the two depart or lie on the bottom in parallel with ventral surfaces down. Over half the copulatory bouts involved more than one male, with a few insertions and copulations involving two or more males.


    Reproduction is ovoviviparous, with intrauterine development of young being sustained primarily by the large supply of yolk in their yolk-sacs. Young are common in late spring and summer in waters off Florida, when females give birth. Numbers of intrauterine eggs or young are 20 to 30 in a litter. The gestation period is about five to six months and it reproduces every other year. Nursery areas are in shallow turtle-grass beds and on shallow coral reefs. Nurse sharks are slow-growing, with free-ranging tagged juveniles (average about 126 cm long) growing at about 13 cm per year. Males may be 10 to 15 years old at maturity and females 15 to 20 years old (Carrier, 1990; Carrier and Luer, 1990).  The nurse shark feeds heavily on bottom invertebrates such as spiny lobsters, shrimps, crabs, sea urchins, squid, octopus, marine snails and bivalves, and also fish including herring (Clupeidae), sea catfish (Ariidae), mullet (Mugilidae), parrotfish (Scaridae), surgeonfish (Acanthuridae), puffers (Tetraodontidae), and stingrays (Dasyatidae). Algae is occasionally found in its stomach and may be sucked in along with prey animals. Its small mouth and large, bellows-like pharynx allow it to suck in food items at high speed. This powerful suction feeding mechanism and its nocturnal activity pattern may allow the nurse shark to take small, active prey like bony fishes that are resting at night but would be too active and manoeuvrable for this big, lumbering shark to capture in the daytime. When dealing with big, heavy-shelled conchs the nurse shark flips them over and extracts the snail from its shell, presumably by grabbing its body with its teeth and by suction. It will dig under coral detritus and in sand with its head to root out prey.

    Young nurse sharks have been observed resting with their snouts pointed upward and their bodies supported off the bottom on their pectoral fins; this has been interpreted as possibly providing a false shelter for crabs and small fishes that the shark then ambushes and eats. In captivity the nurse shark, when stimulated by food in the form of cut fish, will cruise in circles close to the bottom searching for the food, with its barbels touching or nearly touching the bottom; when it contacts a chunk of food, it may overshoot it but then quickly backs up and rapidly sucks it in. It may even work over vertical surfaces with its barbels.
    Size
    Maximum said to be 430 cm long but most adults are under 3 m long and the largest reliably reported were 280 to 304 cm. Newborn young are about 27 to 30 cm. Males mature at about 210 cm and adult males reach at least 257 cm; females are immature at 225 to 235 cm and mature mostly at about 230 to 240 cm (though one adult female 152 cm long has been reported) and reach over 259 cm.
    Interest to Fisheries
    This shark is commonly captured in local artisanal fisheries in some areas where it occurs, particularly the tropical western Atlantic. It was, however, rare in a localized broad-spectrum fishery out of Guaymas, Mexico (examined by the writer in 1974).
    It has been prized for its extremely tough, thick, armour-like hide, which makes an exceptionally good leather, but is also used fresh and salted for human consumption, as well as for liver oil and fish meal. The stratoconidia (earstones) of this shark and other species are said to be used as a diuretic by local fishermen in southern Brazil.It is easily captured with line gear, gill nets, fixed bottom nets and bottom trawls, and spears. It can be readily captured on sportsfishing tackle, but is generally regarded as being too sluggish to be much of a game fish (unlike the tawny nurse shark in Australia). Divers have sometimes speared nurse sharks, which is inane 'sport' because of its senselessness. The sharks are often sitting ducks for spearfishing divers on the bottom, and the modest speed of these sharks even when active make them no great challenge to hit. However, the toughness of these sharks may make them difficult to subdue underwater, and a diver that spears one may receive a well-deserved bite. The nurse shark was regarded as a pest by fishermen in the Lesser Antilles because it rifled fish traps for food.

    Conservation Status : The conservation status of the nurse shark needs to be assessed throughout its range, but particularly offWest Africa, parts of the tropical western Atlantic and in the eastern Pacific where intensive inshore fisheries are being pursued and the distribution and abundance of these sharks is sketchily known. They are regarded as particularly vulnerable to overexploitation because of their slow growth, low reproductive rate, inshore habitat, apparent site-specificity, their presence in areas with intense inshore fisheries, and very little catch data available. The USAwas the only country reporting nurse shark catches (214 t in 1995) to FAO over the vast range of this shark, and this was only reported during the last decade. Apart from their vulnerability to inshore fisheries, these sharks have been increasingly captured for private and public aquaria, and may have declined in some areas as a result of exploitation. Carrier (1996) and Carrier and Pratt (1998) suggested that public entry should be banned during the late spring and summer at one nurse shark breeding site in the Dry Tortugas National Park, Florida Keys, to avoid disturbing the mating of the sharks in shallow water. These sharks are a major asset to ecotourism in the Caribbean, and probably generate far more revenue there as live sharks viewed by divers than as fisheries products.
    Local Names
    Mexico : Sand shark ,  Gata .
    West Indies : Sand shark ,  Gata .
    Brazil : Gata atlantica ,  Cacao lixa .
    Remarks
    Threat to humans: The nurse shark is generally regarded as harmless to people, because of its sluggishness during the day and relatively small teeth, and is a popular subject for ecotouristic divers, with dive sites to view this shark mostly in the Bahamas but also off Belize, Turks and Caicos, and Florida. In the Caribbean and off Florida people frequently come in contact with it underwater, and it mostly will not respond defensively when approached and usually swims away when disturbed. There have been a small number of nonfatal, unprovoked incidents of nurse sharks biting swimmers and divers. Nonfeeding aggression, possibly related to courtship, defensive threat, or a defensive response to physical contact is possible as the motivation for such encounters. The small prey taken by these sharks and lack of mammalian meat in their diet suggests that predation on people is most improbable. In one unusual and somewhat amusing (but not to the diver) unprovoked incident a large nurse shark grabbed a diver's chest with its teeth, then appeared to hold onto his body with its pectoral fins; the encounter suggests displaced courtship, but unfortunately the sex of the shark was not recorded. More commonly people attempt to ride, spear, grab or otherwise harass this shark, or accidentally step on one while wading, and get bitten as a result. Juveniles are thought to be more prone to turn and bite than adults, which often swim away. Although its teeth are small, the jaws and associated muscles of the nurse shark are powerful and vice-like; in some instances nurse sharks have bitten people and held on, and had to be pried loose with a tool. Hence one should treat these sharks with due respect and enjoy their presence underwater without harassing them.
    Source of Information
    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). Leonard J.V. Compagno 2001.  FAO Species Catalogue for Fishery Purposes. No. 1, Vol. 2. Rome, FAO. 2001. p.269.
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