of Japan and Australia, but not around New Zealand. Annual migration Sand tigers in South Africa and Australia undertake an annual migration that may cover more than . They pup during the summer in relatively cold water (temperature ca. ). After parturition, they swim northwards toward sites where there are suitable rocks or caves, often at a water depth ca. , 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 . 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 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. Behavior Hunting 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 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. Diet 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, skates, other rays, lobsters, crabs and squid. In Argentina, the prey includes mostly demersal fishes, e.g. the striped weakfish (Cynoscion guatucupa)