Sharks are one of the oldest species surviving from the time of the dinosours and one of our arch-enemies. Sharks are one of the main reasons why many people are afraid of the open sea. In WWII more sailors were afraid of shark attacks than the enemy. Sharks have long fought with the human kind and are very experienced with that. They know thay can't face humanity in an open fight that's why they use tactics close to guerilla tactics. They attack children and injured people. It is a myth that they can only smell the blood of people. No they know when a person is in the water but they also know that if the person is bleeding they will be weaker. Thankfully most of the sharks have accepted their fate of a lesser kind than humanity so they don't pose a threat to us, but there are several dedicated to destroying humanity and in recent years we can see that they are getting organized and more active and aggressive. Unfortunately we have not put enough energy into kicking the sharks out of our waters.