This is fascinating stuff. Once between flights in an airport I met a guy who had seen Youtube videos of white (Beluga) whales in Alaska and, according to him, noticed something that no one else had. He'd observed that while the whales had no dorsal fins, they were able to contract their bodies along their sleek sides and form them into a kind of triangular cross-section effectively giving their spine-side a more vertical shape. His observations had gotten him a free trip to Alaska to tell people about it.