1.Dolphins use echolocation, often known as sonar, to see where obstacles are underwater.
2.Dolphins are warm-blooded mammals, not a cold-blooded fish. They have a blowhole on top of their heads, so they stay 15-20 feet below the water, and come up periodically to breathe.
3.Dolphins have a huge lung capacity, and can be under water for 15 minutes.
4. Dolphins have their own language. They use a combination of clicks and other sounds to communicate, which they use to coordinate activities, or teach other dolphins how to do things.
5.Dolphins are always alert; they sleep with only one eye open, and half of their brain shutting down at a time.
