About Carcharias taurus Rafinesque, 1810
Four species are commonly called sand tiger sharks: Carcharias taurus, Carcharias tricuspidatus (the Indian sand tiger shark), Odontaspis ferox (the small-toothed sand tiger shark), and Odontaspis noronhai (the Big-eyed sand tiger shark). Very little is known about C. tricuspidatus, which was described before 1900 and is likely a synonym of C. taurus. O. ferox has a worldwide distribution, is rarely seen, and typically lives in deeper water than C. taurus. O. noronhai is a little-known deep water shark found in the Americas. The most common identification challenge for C. taurus is distinguishing it from the two Odontaspis species. C. taurus is usually spotted, especially on the rear half of its body. Several more reliable identifying traits exist: the lower lobe of its caudal (tail) fin is smaller, its rear dorsal fin is almost as large as its front dorsal fin, its front dorsal fin is relatively non-symmetric, and its front dorsal fin is positioned closer to the pelvic fins than to the pectoral fins, further back on the body. Adult sand tiger sharks (Carcharias taurus) range in length from 2 m (6.6 ft) to 3.2 m (10.5 ft), with most specimens reaching 2.2–2.5 m, and weigh between 91 kg (201 lb) and 159 kg (351 lb). They have a pointed rather than round head, with a flattened, conical snout. Their body is stout and bulky, and their mouth extends beyond the small, lidless eyes. Sand tiger sharks usually swim with their mouth open, displaying three rows of protruding, smooth-edged, sharp-pointed teeth. Males have grey claspers with white tips on the underside of their body. The caudal fin is elongated with a long upper lobe, meaning it is strongly heterocercal. Two large, broad-based grey dorsal fins are set back behind the pectoral fins. C. taurus has a grey-brown back and pale underside; adults usually have scattered reddish-brown spots that are most common on the rear part of the body. In August 2007, an albino C. taurus specimen was photographed off South West Rocks, Australia. The teeth of this shark have no transverse serrations (unlike the teeth of many other shark species), and each tooth has a large, smooth main cusp with a tiny cusplet on each side. Small intermediate teeth separate the upper front teeth from the teeth on the sides of the mouth. Sand tiger sharks inhabit epipelagic and mesopelagic ocean regions, sandy coastal waters, estuaries, shallow bays, and rocky or tropical reefs, at depths up to 190 m (623 ft). They can be found in the Atlantic, Pacific, and Indian Oceans, and the Adriatic Sea. In the Western Atlantic Ocean, they are found in coastal waters from the Gulf of Maine to Florida, in the northern Gulf of Mexico, around the Bahamas and Bermuda, and from southern Brazil to northern Argentina. In the eastern Atlantic Ocean, they occur from the Mediterranean Sea to the Canary Islands, at Cape Verde, along the coasts of Senegal and Ghana, and from southern Nigeria to Cameroon. In the western Indian Ocean, their range extends from South Africa to southern Mozambique, but they do not occur around Madagascar. They have also been sighted in the Red Sea and may range as far east as India. In the western Pacific, they have been sighted in waters off the coasts of Japan and Australia, but not around New Zealand. The reproductive pattern of C. taurus is similar to that of many other species in Odontaspididae, the shark family it belongs to. Female sand tiger sharks have two uterine horns. During early embryonic development, each uterine horn may hold up to 50 embryos, which get nutrients from their yolk sacs and may also consume uterine fluids. Once one embryo in a uterine horn reaches approximately 10 cm (4 in) in length, it eats all of the smaller embryos, leaving only one large embryo per uterine horn. This process is called intrauterine cannibalism, also known as embryophagy or adelphophagy, which literally means "eating one's brother." While a single female is commonly fertilized by multiple male sand tigers, adelphophagy sometimes leaves only one male with surviving offspring. The surviving embryos continue to feed on a steady supply of unfertilized eggs. After a long labor, the female gives birth to fully independent offspring that are 1 m (3.3 ft) long. Gestation lasts approximately eight to twelve months. Sand tiger sharks give birth only every two or three years, resulting in an average reproductive rate of less than one pup per year, which is one of the lowest reproductive rates among sharks. In Argentina, the prey caught by sand tiger sharks largely overlaps with targets of important commercial fisheries. Human activity reduces the food available to sand tiger sharks, and the sharks compete with humans for food that has already been heavily exploited by the fishing industry. This same competitive dynamic applies to the bottom-dwelling sea catfish Galeichthys feliceps, a commercial fisheries resource off the coast of South Africa.
