Dolphins of Atlanta

Here are the dolphins of Atlanta. There are so many questions: why are they here? Why dolphins? Are there more of them? And why is one of them wearing a cape?

To which I have no answers at all. 

They appear to have been paid for by Southern Company and the Twelve Hotel. 

The second dolphin is painted with Atlanta landmarks like skyscrapers, the coke museum, the braves, and the varsity burger joint.