At birth, beluga whales are 5 feet long, roughly 100 pounds, and dark blue-gray in color. Unmistakable as adults, their color lightens to white, and they have a dorsal ridge rather than a fin. Belugas ...

Instead of a dorsal fin, belugas have a dorsal ridge, which allows them to swim under sheets of floating sea ice with ease—an adaptation that helps them hide from orca predators. (Their genus ...