They are warm blooded.
Dolphins use their powerful tail flukes in an up and down motion to move through water.
When a dolphin is slapping its tail on the water it may be a sign of annoyance, so move back and leave the area. Dolphin 'friends' may swim along face to face touching flippers. In the wild an open mouth is a sign of aggression, as is head nodding. A sign of greater aggression is violent jaw clapping. To sleep, a dolphin must shut down only half of its brain, as its breathing is under unvoluntary conrol.