What purpose does the B/W killer whale color scheme serve? And what evolutionary pressure could possibly force all of them to go B/W in such a peculiar way ie with weird patches in the black. Also why not deep blue rather than black? And their diets are mostly near sea surface so I don't see how it helps them hunt, as stated in wiki
Although I'm not much into animal science, but let me try my hands on it.
The entire dorsal (top) surface and pectoral flippers are black except for the gray saddle.
The ventral (bottom) surface, lower jaw, and undersides of the tail flukes are mostly white. The undersides of the tail flukes are fringed with black.
Now let's come up to the main point, why does this happen?
The source I have referred to says there are two reasons :-
The distinctive coloration of killer whales is a type of disruptive coloration, a pattern that obscures the outline of an animal by contradicting the animal's body shape. In the flickering, filtered sunlight of the sea, other animals may not recognize a killer whale as a potential predator.
For the part of evolutionary pressure, it has already been answered on SE, visit Selection Pressure on Orca Whale Coloration