As an adaptation to the Arctic, which anatomical characteristic serves the beluga whale to swim with ease?

The beluga is an Arctic and sub-Arctic cetacean. It is also known as the white whale, as it is the only cetacean to regularly occur with this color. Another nomenclature is sea canary, due to its high-pitched calls. One other name is melon-head, though that more commonly refers to the melon-headed whale, which is an oceanic dolphin.

The unique adaptation to life in the Arctic, is an anatomical characteristic that differentiates it from other cetaceans -the absence of a dorsal fin that allows it to swim under the ice with ease.

Like other cetaceans, it possess an echolocation organ called a melon, at the front of its head, which in this species is large and deformable.

The body size is between that of a dolphin and a true whale, with males growing up to 5.5 m (18 feet) long and weighing up to 1,600 kg (3,530 pounds).

They are gregarious and form groups of 10 animals on average, although during the summer, they can gather in the hundreds or even thousands in estuaries and shallow coastal areas.