See also here.
Long-snouted spinner dolphins are relatively small for oceanic dolphins, growing only about 7 feet long (the bottlenose dolphin is about 10 feet long). Spinner dolphins are highly social and are often seen in pods of hundreds of dolphins. Like all dolphins, spinners communicate by echolocation, which is an elaborate series of clicks and whistles. Spinner dolphins also slap the surface of the water with their fins to communicate: here.