The maximum size of this species has been given variously as ~3.2 m by Compagno (1984a), ~2.75 m and ~142 kg by Hutchins and Swainston (1986) and ~3.2 m and ~300 kg by Hutchins and Thompson (1983). Catch records from beach meshing in NSW, however, suggest that these sharks may grow to 4.3 m, though this maximum length is doubtful and may be due to a misidentification (Reid and Krough 1992).

Branstetter and Musick (1994) described the age and growth of C. taurus in the western North Atlantic based on banding patterns on vertebral centra and stated the maximum age to be 30?35 years. The largest (oldest) male examined (248 cm TL) from the south-eastern USA was 7.5 years old, and the largest (oldest) female examined (272 cm TL) was 10.5 years old. The hypothesis of double annual ring formation is currently being re-examined. If only one ring is deposited each year, the ages cited above would be approximately doubled (J. Musick pers. comm.). The oldest individuals recorded in aquaria were 13 years in Australia (Roughley 1955) and 16 years in South Africa (Govender et al. 1991).

The Grey Nurse Shark occurs either alone or in small to medium-sized aggregations of 20?80 individuals (Silvester 1977, Aitken 1991, Cliff unpubl.). These sharks are often observed hovering motionless just above the seabed in or near deep sandy-bottomed gutters or rocky caves, usually in the vicinity of inshore rocky reefs and islands. They are generally coastal, usually being found from the surf zone down to depths of around 25 m. However, they may also occasionally be found in shallow bays, around coral reefs and, very rarely, to depths of around 200 m on the continental shelf. They usually live near the bottom, but may also move throughout the water column (Compagno 1984a).

Males and females both mature at approximately 2 m in length off the south-eastern USA (Gilmore et al. 1983). They are ovoviviparous and usually only two pups are born per litter once every two years. This is because the remaining eggs and developing embryos are eaten by the largest and/or most advanced embryo in each horn of the uterus (a phenomenon known as adelphophagy or uterine cannibalism). The gestation period may last from 9?12 months and size at birth is relatively large, at about 1 m (Gilmore et al. 1983, Gilmore 1993).

Grey Nurse Shark populations off South Africa and the east coast of the USA are known to undertake complex size and sex segregated migrations. These have been documented by Bass et al. (1975c), Gilmore (1993) and Musick et al. (1993). In other parts of its range and particularly in south-eastern Australia, this species appears to undertake similar migrations.

The species feeds on a wide range of teleost fishes, as well as smaller sharks (Carcharhinidae and Triakidae), rays (Myliobatidae), squids, crabs and lobsters (Compagno 1984, Gelsleichter et al. 1999). Scott et al. (1974) reported that Grey Nurse Sharks in south-eastern Australia fed on shoals of Australian salmon (Arripidae) and other pelagic fish species.