An old picture i made in GIMP before I was any good at it (and no I'm still no good at it, just better than I sued to be =P). Its probably more of a whale than a dolphin, and color pattern adapted from ociunus orca.

Took it from a sketch to vectors with Gimp, then a quick paint job. Sadly I could not find a satisfactory way to antialias it. I'm still happy with it.