Dolphins live in warm oceans near coral reefs, coastal regions, and river streams. They have adapted over millions of years to live in the water, developing a blowhole on their back to breathe. Dolphins communicate and echolocate using clicks and squeaks produced by opening and closing their blowhole. They live in pods of up to 100 dolphins for protection from predators like sharks and killer whales, and for cooperation in hunting and caring for one another.