In spite of the bottlenose dolphin's gentle appearance, All About Wildlife explains that these animals are in fact apex predators. While great white sharks, tiger sharks and bull sharks occasionally prey on young dolphins, bottlenose dolphins are known to attack and kill sharks. All About Wildlife states that bottlenose dolphins kill or injure sharks by using their snouts to ram the sharks' vulnerable gills.
All About Wildlife goes on to explain that humans are the only significant threat to bottlenose dolphins. Bottlenose dolphins have ways to defend themselves from every other creature in the sea. Even when ramming a threat doesn't work to kill it or drive it off, a bottlenose dolphin is intelligent enough to come up with other ways to protect itself. However, Clearwater Marine Aquarium states that bottlenose dolphins are so adept at fighting off predators that they almost always resort to aggression.
According to Clearwater Marine Aquarium, bottlenose dolphins travel in large family groups and don't truly sleep, meaning they are capable of constantly communicating with one another to stay alert. Bottlenose dolphins communicate using high-pitched sounds unique to each individual. These complex sounds keep a bottlenose dolphin's family members informed on its location and surroundings, ensuring any possible threat is recognized as quickly as possible.