defensive behavior!!!
The dolphins are very aggressive when their instincts tell them some animal/fish is mean. They are very aggressive and can kill sharks! They're afraid of sharks but when it comes time to fight they are ready to kill if thats what it means to survive! Their eyesight, speed, agility, and hearing noises they know help them. The noises can tell other dolphins to watch out while they are there. The noise that they make is called echolocation. They make this sound because the shark is nearby or to call for help,to make sure thier is other dolphins there too.