Marine mammal, the Beluga is a totally white cetacean in adulthood, living in the Arctic Ocean. It can measure up to 20 feet and weigh more than 1.5 ton. Unlike many other cetaceans, it does not have a dorsal fin, but a dorsal ridge resulting from the atrophy of the latter. It also has a sonar, the most sophisticated cetacean, allowing it to navigate the labyrinth of arctic ice water channels.