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.

Nurse shark

The nurse shark (Ginglymostoma cirratum) is a shark in the family Ginglymostomatidae. Nurse sharks can reach a length of 3.08 m (10.1 ft).

Taxonomy

The nurse shark family name, Ginglymostomatidae, derives from the Greek: from γίγγλυμος meaning hinge and στόμα meaning mouth. Cirratum also derives from Greek, meaning curl or swim. Based on morphological similarities, Ginglymostoma is believed to be the sister genus of Nebrius, with both being placed in a clade that also contains the Pseudoginglymostoma brevicaudatum, Rhincodon typus, and Stegostoma fasciatum.

Distribution and habitat

The nurse shark is a common inshore bottom-dwelling shark, found in tropical and subtropical waters on the continental and insular shelves. It is frequently found at depths of one meter or less but may occur down to 75 m (246 ft). Its common habitats are reefs, channels between mangrove islands and sand flats. It can be seen in the Western Atlantic from Rhode Island down to southern Brazil; in the Eastern Atlantic from Cameroon to Gabon (and possibly ranges further north and south) and around the islands of the Caribbean.