The great white shark is the largest predatory shark alive. It averages at around 16 feet in length, but can reach up to 20 feet. Great whites' diet ranges from seals to fish, even other sharks. Its only known predator is the killer whale, although it may be attacked by a saltwater crocodile that becomes territorial. Great whites are found mainly in Africa and Australia, although they have been sighted in parts of the Americas. They are not really the cold hearted killers that we believe them to be. In fact, some people have swam with great whites and left without a scratch. They cant normally be kept in captivity, for they need much more air than we can provide. However, young white sharks have been held captive, and released at an appropriate age.