The skin of a bottlenose dolphin is gray, smooth, and rubbery. They are always social. They can help each other fight off predators. Dolphins have fought off sharks in this way. They can kill large sharks by ramming them over and over again with their snouts and heads. They look after the young, when the mothers need to leave their calves to hunt for food. The young need to breathe more often than the adults, and the food may be in deeper waters.