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BiologyDespite its worldwide notoriety, very little is known about the natural ecology and behaviour of this predator. These sharks are usually solitary or occur in pairs, although it is apparently a social animal that can also be found in small aggregations of 10 or more, particularly around a carcass (3) (6). Females are ovoviviparous; the pups hatch from eggs retained within their mother's body, and she then gives birth to live young (10). Great white sharks are particularly slow-growing, late maturing and long-lived, with a small litter size and low reproductive capacity (8). Females do not reproduce until they reach about 4.5 to 5 metres in length, and litter sizes range from two to ten pups (8). The length of gestation is not known but estimated at between 12 and 18 months, and it is likely that these sharks only reproduce every two or three years (8) (11). After birth, there is no maternal care, and despite their large size, survival of young is thought to be low (8). Great whites are at the top of the marine food chain, and these sharks are skilled predators. They feed predominately on fish but will also consume turtles, molluscs, and crustaceans, and are active hunters of small cetaceans such as dolphins and porpoises, and of other marine mammals such as seals and sea lions (12). Using their acute senses of smell, sound location and electroreception, weak and injured prey can be detected from a great distance (7). Efficient swimmers, sharks have a quick turn of speed and will attack rapidly before backing off whilst the prey becomes weakened; they are sometimes seen leaping clear of the water (6). Great whites, unlike most other fish, are able to maintain their body temperature higher than that of the surrounding water using a heat exchange system in their blood vessels (11).