The United Nations’s Food and Agricultural Organization lists 354 species of sharks, ranging in length from 6 inches (15 centimeters) to 49 feet (15 meters). While 35 species are known to have attacked humans at least once, only a dozen do so on a regular basis. The relatively rare great white shark (Carcharodan carcharías) is the largest predatory fish. The largest specimen accurately measured was 20 feet, 4 inches (6.2 meters) long and weighed 5,000 pounds (2,270 kilograms).