A sand tiger is a type of shark that lives in shallow waters. Also called the grey nurse shark in Australia, these sharks are mostly harmless to humans. There has been considerable debate among scientist as to the genus these sharks actually belong in, resulting in three changes in their scientific name since their discovery. The most common scientific name in use is Carcharias taurus, but they also may be referred to as Eugomphodus taurus and Odontaspis taurus.
Light brown with a pale underbelly, sand tigers are on average 4-9 feet (1.2-2.7 m) long, with a maximum length of 10.5 feet (3.2 m). Unusual to many sharks, sand tigers have two dorsal fins and an anal fin that are all about the same size. Their tail, or caudal, fin is asymmetrical. Sand tigers usually live about 15 years in the wild.
Sand tigers have short, flat snouts. They also have three rows of teeth in the front of their upper and lower jaws. The teeth are sharp and narrow and have small prongs jutting out of the base.
Living in temperate or tropical coastal waters, shallow bays, and tropical reefs, a sand tiger is generally not found at depths greater than 230 feet (70 m). Usually slow swimmers, these sharks are more active at night. They eat only two percent of their body weight a week, sometimes less in winter months. Their diet consists of crustaceans, small sharks, squids, and small and large fish.
A sand tiger female is ovoviviparous, meaning though she gives birth to live young, the young are incubated in eggs which hatch inside the mother before birth. Only two pups are born at a time because hatching pups eat the other fertilized eggs before they are birthed. When fertilizing the eggs, the male bites the female's pectoral fin, only releasing it when fertilization is complete. Gestation is approximately nine to 12 months.
Upon birth, juvenile sand tigers are usually about 3 feet (1 m) long. Females grow to be larger than males, reaching maturity at about 7 feet (2.2 m) by their sixth year. Males reach maturity around year four or five at about 6 feet (1.9 m) lonh. Juveniles will have red or brown spots near their tail, which fade during the first decade of life.
The Sand tiger is considered endangered in both Australia and the United States. It was the first species of shark to be given federal protected status, in 1997, by the Australian government. In both countries it is illegal to harm or to intentionally fish for these sharks. In Japan, however, they are caught commercially and used as food.