<P> Sand tigers in South Africa and Australia undertake an annual migration that may cover more than 1,000 km (620 mi). They pup during the summer in relatively cold water (temperature ca . 16 ° C). After parturition, they swim northwards toward sites where there are suitable rocks or caves, often at a water depth ca . 20 m (66 ft), where they mate during and just after the winter . Mating normally takes place at night . After mating, they swim further north to even warmer water where gestation takes place . In the Autumn they return southwards to give birth in cooler water . This round trip may encompass as much as 3,000 km (1,900 mi). The young sharks do not take part in this migration, but they are absent from the normal birth grounds during winter: it is thought that they move deeper into the ocean . At Cape Cod (USA), juveniles move away from coastal areas when water temperatures decreases below 16 ° C (61 ° F) and day length decreases to less than 12 h . Juveniles, however, return to their usual summer haunts and as they become mature they start larger migratory movements . </P> <P> The sand tiger shark is a nocturnal feeder . During the day, they take shelter near rocks, overhangs, caves and reefs often at relatively shallow depths (<20 m). This is the typical environment where divers encounter sand tigers, hovering just above the bottom in large sandy gutters and caves . However, at night they leave the shelter and hunt over the ocean bottom, often ranging far from their shelter . Sand tigers hunt by stealth . It is the only shark known to gulp air and store it in the shark's stomach, allowing the shark to maintain near - neutral buoyancy which helps it to hunt motionlessly and quietly . Aquarium observations indicate that when it comes close enough to a prey item, it grabs with a quick sideways snap of the prey . The sand tiger shark has been observed to gather in hunting groups when preying upon large schools of fish . </P> <P> The majority of prey items of sand tigers are demersal (i.e. from the sea bottom), suggesting that they hunt extensively on the sea bottom as far out as the continental shelf . Bony fish (Teleosts) form about 60% of sand tigers food, the remaining prey comprising sharks and skates . In Argentina, the prey includes mostly demersal fishes, e.g. the striped weakfish (Cynoscion guatucupa). The most important elasmobranch prey is the bottom - living smooth - hound shark (Mustelus sp .). Benthic (i.e. free - swimming) rays and skates are also taken . Stomach content analysis indicates that smaller sand tigers mainly focus on the sea bottom and as they grow larger they start to take more benthic prey . This perspective of the diet of sand tigers is consistent with similar observations in the north west Atlantic and in South Africa where large sand tigers capture a wider range of shark and skate species as prey, from the surf zone to the continental shelf, indicating the opportunistic nature of sand tiger feeding . Off South Africa, sand tigers less than 2 m (6 ft 7 in) in length prey on fish about a quarter of their own length; however, large sand tigers capture prey up to about half of their own length . The prey items are usually swallowed as three or four chunks . </P> <P> Mating occurs around the months of March and April in the northern hemisphere and during August--October in the southern hemisphere . The courtship and mating of sand tigers has been best documented from observations in large aquaria . In Oceanworld, Sydney, the females tended to hover just above the sandy bottom ("shielding") when they were receptive . This prevented males from approaching from underneath towards their cloaca . Often there is more than one male close by with the dominant one remaining close to the female, intimidating others with an aggressive display in which the dominant shark closely follows the tail of the subordinate, forcing the subordinate to accelerate and swim away . The dominant male snaps at smaller fish of other species . The male approaches the female and the two sharks protect the sandy bottom over which they interact . Strong interest of the male is indicated by superficial bites in the anal and pectoral fin areas of the female . The female responds with superficial biting of the male . This behaviour continues for several days during which the male patrols the area around the female . The male regularly approaches the female in "nosing" behaviour to "smell" the cloaca of the female . If she is ready, she swims off with the male, while both partners contort their bodies so that the right clasper of the male enters the cloaca of the female . The male bites the base of her right pectoral fin, leaving scars that are easily visible afterwards . After one or two minutes, mating is complete and the two separate . Females often mate with more than one male . Females mate only every second or third year . After mating, the females remain behind, while the males move off to seek other areas to feed, resulting in many observations of sand tiger populations comprising almost exclusively females . </P>

What's the difference between a tiger shark and a sand tiger shark