The grey nurse shark (Australia), spotted ragged-tooth shark (Africa) or sand tiger shark (US and UK), Carcharias taurus, is a large shark inhabiting coastal waters worldwide, with many different names in different countries in the world. Despite a fearsome appearance and strong swimming abilities, it is a relatively placid and slow moving animal. It is considered not aggressive unless provoked.
Anatomy and appearance
The body is stout, with two large dorsal fins
and the tail is elongated and has a long upper lobe. The shark has a precaudal pit but no caudal keels. It grows to a length of 3.2 m
(about 10.5 ft
). Male grey nurse sharks mature at 2.1 m (about 6' 11"); and females mature at 2.2 m (about 7' 3"). This shark weighs 90 to 160 kg
(200 to 350 lb
The grey nurse shark usually has a grey back and white underside. In August 2007, an albino specimen was photographed off South West Rocks, Australia.
The diet of Carcharias taurus
consists of bony fishes
, other sharks and rays
The sharks typically congregate in coastal waters, at depths of between 60 and 190 m, although deeper depths have been recorded. Often they will shelter in caves or gutters during the day, and come out at night to feed. During the day they exhibit sluggish behavior, becoming more active during the night. The grey nurse shark is the only known shark to gulp and store air in its stomach in order to maintain neutral buoyancy while swimming.
While it is commonly reported that grey nurse sharks are harmless , data compiled by ISAF records 76 attacks on humans, of which 29 have been classified as unprovoked. Two of those unprovoked attacks have resulted in fatalities.
However, it can be calm during daytime and in aquariums it is a very common species.
The species is ovoviviparous
, i.e. bearing live young from eggs which hatch inside the uterus. Female sharks have two uteruses. Inside the uterus the young sharks develop and eat each other, so typically only two young sharks are born for each gestation period, which lasts six to nine months. This process, also known as intrauterine cannibalism
, is making it harder for the shark population to rebound from near extinction. As a result, scientists plan to artificially inseminate
and breed the sharks, in order to increase their population. Another plan is to remove the shark embryos from the uterus before cannibalism can take place and then artificially gestate them.
It is listed as vulnerable
on the IUCN Red List
, and as endangered
under Queensland's Nature Conservation Act 1992
. For further information on conservation status and measures, see grey nurse shark conservation
- Database entry includes justification for why this species is vulnerable
- Barry Bruce, John Stevens, Nick Otway: Site fidelity, residency times and activity space in grey nurse sharks in eastern Australia