The great white shark is one of the oldest living species on Earth-it existed 350 million years ago. It is the largest and the most dangerous predatory fish,and it is the most feared by humans. Great white sharks can grow up to 20 feet (6 meters) long and weigh up to 4,400 pounds (2,000 kilograms). They have about 3,000 teeth arranged in several rows. When the front teeth break or all out, these teeth are replaced by others from the next row. Sharks’ hearing is very sensitive, and they can hear their prey many miles away. They can also detect one part per million of blood in seawater.