Author: (Rafinesque, 1810)
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.
Possibly rounded-pointed snout and presence of labial furrows (see account of Eugomphodus tricuspidatus).
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 lslands, Senegal, Ghana, southern Nigeria to Cameroon. Western Indian Ocean: South t Africa to southern Mozambique; Red Sea, Pakistan, ? India. Western Pacific: ? Indonesia, ? Viet Nam, Japan, China; Australia (Queensland, New South Wales, Victoria, Tasmania, South Australia, Western Australia).
Habitat and Biology:
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 on the outer shelves. 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 autumn 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 sometime 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 bonyfishes including herrings, croakers, bluefishes, bonitos, butterfishes, snappers, hakes, eels, wrasses, mullets, spadefishes, sea robins, sea basses, porgies, remoras, sea catfishes, flatfishes, jacks, bnd undoubtedly many others, as well as small sharks (Carcharhinidae and Triakidae), rays (Myliobatidae), squids, crabs and lobsters. Schools of this shark have been observed to feed cooperatively, surrounding and bunching schooling prey and then feeding on them.
As the "grey nurse" shark, this species has a bad reputation as a maneater in Australian waters, but this is apparently due to confusion with other species, particularly requiem sharks (Carcharhinidae). Observations of this shark underwater suggest that it is primarily inoffensive and unaggresive towards people when not provoked, though its size and jagged dentition should invite respect. However, it can be stimulated to harass and attack people, particularly when they are spearfishing. Cases are known of this shark stealing fish off stringers and spears underwater, underlining the desirability of boating one's catch as soon as possible when this shark or others are about. Relatively few documented attacks by this shark on people have been reported. On the other hand, divers armed with powerheads and other underwater weapons have found this slow-moving species an easy target in some areas (particularly Australia); such crude and barbaric 'sport', analogous to shooting domestic cattle with a pistol, has caused a decline in the number of these sharks where it occurs.
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.
Interest to Fisheries:
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.
AUSTRALIA: Gray nurse shark; SOUTH AFRICA: Spotted ragged-tooth shark.
Included as synonyms of E. taurus are anumber 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 dentitional characters most often used to distinguish these species (see Bigelow and Schroeder, (1948) apparently vary considerably within samples from a given area (Applegate, 1965, Sadowsky, 1970, Taniuchi, 1970). These include Squalus americanus and 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 and Pollard (1980) have all used the species name taurus for the local representatives of the species formerly named owstoni, arenarius, and platensis.
Holotype: Unkown. Type Locality: Sicily, Mediterranean Sea.