Ragged-tooth shark (Carcharias taurus).
Spotted Ragged-tooth sharks (Carcharias taurus), also known as sand tiger or grey nurse sharks can be found along the south and east coast of South Africa. They are usually found alone or in small groups, but can aggregate in groups of 20-80 individuals. Raggies are mostly found hovering motionless just above the seabed near shallow reefs and are able to actively pump water over their gills enabling them to breathe.
Raggies are a large shark species and can reach lengths of 320 cm and weigh 300kg. They can range in colour from light brown to grey and have large brown spots covering the body. They have two equally sized dorsal fins and permanently visible long and dagger-formed teeth (tricuspid). They have two rows of teeth in both jaws and can lose 2-3 teeth a day. Due to their physical appearance they were believed to be dangerous sharks, but are mostly harmless to humans unless provoked. They have also been known to harass spear fishermen.
Raggies are a wide-ranging coastal species but are primarily found in warm-temperate and tropical waters all over the world. Off South Africa Raggies have occasionally been reported on the west coast, but are commonly found along the east coast from Cape Town to northern KwaZulu–Natal (KZN).
Raggies sexually mature at 2m in length. A pregnant female will migrate along the coast line to the most suitable water temperature for different parts of their gestation. They spend the main part of their pregnancy in warm waters like northern KZN and will migrate to colder waters of the Eastern Cape to give birth to two pups. Raggies are ovoviviparous (has eggs, but will give birth to live young) and the pups are uterus-cannibals (will eat all the other siblings in the uterus before birth). The gestation period is 9-12 months and the pups are about 1m in length when born.
The international conservation status for ragged-tooth sharks is vulnerable. They used to be classified as endangered, but have increased in numbers. Their increase is slow because they only give birth to 2 pups ever 2 years and have a short life span of 25-35 years. They were hunted for their liver oil and fins for the shark fin trade. They were also killed when found in shallow waters because of their threatening appearance. Raggies are popular targets of shore anglers, but of more concern is the increasing tourism activity of scuba diving. Raggies tend to congregate on their breeding grounds which are relatively easily accessible to divers. The constant disturbance could eventually cause them to move away from their favoured sites, potentially causing stress to their natural reproductive cycles.
• 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, 127–134
• Barker S.M. Peddemors V.M. Jane E. 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 Vol. 44, No. 2, 75–92
• Van der Elst R. 1993. A guide to the common Sea Fishes of Southern Africa. Struik publishers