Sand tiger shark

The sand tiger shark (Carcharias taurus), grey nurse shark, spotted ragged-tooth shark, or blue-nurse sand tiger is a species of shark that inhabits subtropical and temperate waters worldwide. It inhabits the continental shelf, from sandy shorelines (hence the name sand tiger shark) and submerged reefs to a depth of around 191 m (627 ft). They dwell in the waters of Japan, Australia, South Africa, the Mediterranean and the east coasts of North and South America. Despite its name, it is not related to the tiger shark Galeocerdo cuvier; however, it is a cousin of the great white shark Carcharodon carcharias. Despite its fearsome appearance and strong swimming ability, it is a relatively placid and slow-moving shark with no confirmed human fatalities. This species has a sharp, pointy head, and a bulky body. The sand tiger's length can reach 3.2 m (10.5 ft). They are grey with reddish-brown spots on their backs. Shivers (groups) have been observed to hunt large schools of fish. Their diet consists of bony fish, crustaceans, squid, skates and other sharks. Unlike other sharks, the sand tiger can gulp air from the surface, allowing it to be suspended in the water column with minimal effort. During pregnancy, the most developed embryo will feed on its siblings, a reproductive strategy known as intrauterine cannibalism i.e. 'embryophagy' or, more colorfully, adelphophagy—literally 'eating one's brother'. The sand tiger is categorized as vulnerable on the International Union for Conservation of Nature Red List. It is the most widely kept large shark in public aquariums owing to its tolerance for captivity. The sand tiger shark's description as Carcharias taurus by Constantine Rafinesque came from a specimen caught off the coast of Sicily. Carcharias taurus means 'bull shark'. This taxonomic classification has been long disputed. Twenty-seven years after Rafinesque's original description the German biologists Müller and Henle changed the genus name from C. taurus to Triglochis taurus. The following year, Swiss-American naturalist Jean Louis Rodolphe Agassiz reclassified the shark as Odontaspis cuspidata based on examples of fossilized teeth. Agassiz's name was used until 1961 when three palaeontologists and ichthyologists, W. Tucker, E. I. White, and N. B. Marshall, requested that the shark be returned to the genus Carcharias. This request was rejected and Odontaspis was approved by the International Code of Zoological Nomenclature (ICZN). When experts concluded that taurus belongs after Odontaspis, the name was changed to Odontaspis taurus. In 1977, Compagno and Follet challenged the Odontaspis taurus name and substituted Eugomphodus, a somewhat unknown classification, for Odontaspis. Many taxonomists questioned his change, arguing that there was no significant difference between Odontaspis and Carcharias. After changing the name to Eugomphodus taurus, Compagno successfully advocated in establishing the shark's current scientific name as Carcharias taurus. The ICZN approved this name, and today it is used among biologists. Because the sand tiger shark is worldwide in distribution, it has many common names. The term 'sand tiger shark' actually refers to four different sand tiger shark species in the family Odontaspididae. Furthermore, the name creates confusion with the unrelated tiger shark Galeocerdo cuvier. The grey nurse shark, the name used in Australia and the United Kingdom, is the second-most used name for the shark, and in India it is known as blue-nurse sand tiger. However, there are unrelated nurse sharks in the family Ginglymostomatidae. The most unambiguous and descriptive English name is probably the South African one, spotted ragged-tooth shark. There are four species of sand tiger sharks The most likely problem when identifying the sand tiger shark is when in the presence of either of the two species of Odontaspis. Firstly, the sand tiger is usually spotted, especially on the hind half of the body. However, there are several other differences that are probably more reliable: Adult sand tigers range from 2 m (6.6 ft) to 3.2 m (10.5 ft) in length and 91 kg (201 lb) to 159 kg (351 lb) in weight. The head is pointy, as opposed to round, while the snout is flattened with a conical shape. Its body is stout and bulky and its mouth extends beyond the eyes. The eyes of the sand tiger shark are small, lacking eyelids. A sand tiger usually swims with its mouth open displaying three rows of protruding, smooth-edged, sharp-pointed teeth. The males have grey claspers with white tips located on the underside of their body. The caudal fin is elongated with a long upper lobe (i.e. strongly heterocercal). They have two large, broad-based grey dorsal fins set back beyond the pectoral fins. The sand tiger shark has a grey-brown back and pale underside. Adults tend to have reddish-brown spots scattered, mostly on the hind part of the body. In August 2007, an albino specimen was photographed off South West Rocks, Australia. The teeth of these sharks have no transverse serrations (as have many other sharks) but they have a large, smooth main cusp with a tiny cusplet on each side of the main cusp. The upper front teeth are separated from the teeth on the side of the mouth by small intermediate teeth. Sand tiger sharks roam the epipelagic and mesopelagic regions of the ocean, sandy coastal waters, estuaries, shallow bays, and rocky or tropical reefs, at depths of up to 190 m (623 ft).