Bull sharks are responsible for most shark attacks as they use a 'bump and bite' strategy to attack their prey, making them dangerous catch while fishing. Despite being accustomed to saltwater, they can venture into freshwater, traveling as far as Illinois, making them adaptable and dangerous predators known to attack even in rivers like in the movie 'Jaws' where the attack was based on a New Jersey river. Their ability to transition from saltwater to freshwater showcases their adaptability and predatory nature.