White Whale By Andrey Nekrasov

Belugas have a dorsal ridge, rather than a dorsal fin. The absence of the dorsal fin is reflected in the genus name of the species—apterus the Greek word for "wingless." The evolutionary preference for a dorsal ridge rather than a fin is believed to be an adaptation to under-ice conditions, or possibly as a way of preserving heat. As in other cetaceans, the thyroid gland is relatively large compared to terrestrial mammals (proportionally three times as large as a horse's thyroid) and may help to sustain higher metabolism during the summer estuarine occupations.
Its body is round, particularly when well-fed, and tapers less smoothly to the head than the tail. The sudden tapering to the base of its neck gives it the appearance of shoulders, unique among cetaceans. The tail fin grows and becomes increasingly and ornately curved as the animal ages. The flippers are broad and short—making them almost square-shaped.