The Southern Bluefin Tuna are silver bullets of the deep blue. Fast, graceful swimmers with an almost perfect streamline hydrodynamic that includes eyes that retract to ensure they cut through the water. Southern Bluefin Tuna can swim at up to 70 km (44 mi) per hour when feeding. As they burn energy rapidly, they are constantly on the prowl for food, including other sardines, crustaceans and mollusks. They are always on the move and can eat up to a quarter of their body weight in a single day. This opportunistic feeding results in layers of fat throughout their muscles, which makes them incredibly delicious and one of the most prized culinary fish on the planet.