Great White shark research. Researcher listening for shark movement using an underwater microphone, or hydrophone. He is investigating the behaviour of Great White sharks (Carcharodon carcharias) that have previously been tagged with an acoustic transmitter. The hydrophone picks up the transmitter's sounds as a series of 'pings'. This enables the researcher to determine their approximate location and depth. The Great White is the largest of the predatory sharks, reaching a length of over 6 metres. They feed mainly on seals, turtles and fish. Attacks on humans are rare and more likely due to mistaken identity. Photographed in False Bay, Cape Town, South Africa.