Then teeth appear gradually in the upper jaw, and by adulthood there is a total of 40 teeth in a mouth that looks like it's smiling. Like most other cetaceans, beluga whales don't have hair as adults. Unlike other cetaceans, which tend to make and shed skin continuously, Beluga whales appear to undergo a seasonal molt of the outer layer of skin. During the winter, the top layer of a beluga's skin may turn yellow, especially on its back and flippers. Rubbing on gravel river bottoms helps a beluga shed this layer of skin.
Adult belugas are yellowish-white to creamy white.
Belugas attain their white coloration upon reaching maturity. The Beluga whale has a hole on the top of its head for breathing called a blowhole. Because it's a mammal, it needs the hole to breathe air when it comes to the surface of the water. It lets out old air making a spout called a blow. It then brings fresh air into the blowhole.