Among some species the groups combine and form herds of 100 to 1,000 dolphins. Adult males and young dolphins move among groups of females with their calves. The animals in such groups play and hunt for food together. They also help other members of the group that are in trouble. Dolphins sometimes use their backs or flippers to keep an ill or injured dolphin near the surface.
Dolphins communicate with one another in a variety of ways.
For example, they may use a complex series of whistles and clicks called phonations. The animals make these sounds in air-filled sacs connected to their blowholes. Dolphins also communicate by slapping their flukes on the surface of the water. Swimming and diving. Dolphins swim by moving their flukes up and down.