Dolphins travel in small pods to deter sharks from attacking them, and they avoid predators through the use of echolocation. When attacked, a dolphin's greatest defenses are his maneuverability, powerful tail, nose and teeth.
A dolphin cannot out-swim a shark, but a healthy social animal is not usually at risk for attack. Instead, sharks and other predators target isolated, ill, injured, elderly or infant dolphins. If a dolphin is forced to fight, he may choose to ram his nose into the vulnerable gills or bite down. A group of dolphins works together to defend themselves, but they rarely kill the predator, instead they seek to drive it away.
While most dolphins are too small to battle sharks and are uninterested in initiating fights, a few species such as the killer whale are large and coordinated enough to prey on sharks. Erroneously considered whales, orcas are part of the dolphin family and are named for their size, and their hunting of marine mammals and birds. Orcas hunt in packs, much like wolves, and work to isolate and immobilize their prey. Their echolocation allows them to hunt in dark environments. Both sharks and orcas are considered apex predators. In general, dolphins are carnivores, preferring to hunt and kill crustaceans and fish that cannot fight back.