Delphinapterus

About Delphinapterus

Delphinapterus — "dolphin without a wing" — contains one species, named for the absence of a dorsal fin. Calves are born slate gray or brownish and whiten gradually over five to eight years. The neck vertebrae are unfused, so unlike almost every other cetacean a beluga can turn its head to look at something, and the melon is soft enough to be visibly deformed at will.

It is the most vocal of the large whales, with a repertoire of whistles, clicks, chirps and creaks audible through a wooden hull — the reason nineteenth-century whalers called it the sea canary. Each summer belugas gather in river estuaries in large numbers and rub themselves on gravel shallows to shed a layer of skin, an annual moult unusual among cetaceans.

The species is distributed in discrete populations around the Arctic, several of which are genetically distinct and demographically independent. Some are numerous; the Cook Inlet population in Alaska has failed to recover since hunting was regulated and is listed as critically endangered.