Belugas are small, white Arctic whales. Adults measure 4-5.5 meters (13-18 feet) and weigh 700-1,600 kg (1,500-3,500 lbs), with males larger than females. Calves are born dark grey and gradually lighten, becoming pure white by about seven to nine years of age.
Instead of a dorsal fin they have a tough ridge along the back, an adaptation for swimming under ice. Their neck bones are not fused, so unlike most whales they can turn and nod their heads. The rounded forehead, called the melon, is soft and changes shape as the whale makes sounds and focuses its echolocation.
Belugas are among the most vocal of all whales. Their chirps, whistles, clicks and squeals can be heard through the hull of a boat, which earned them the nickname "canaries of the sea". They live 35-50 years and sometimes longer.
Belugas live in Arctic and sub-Arctic waters around Alaska, Canada, Greenland, Norway and Russia. In summer, thousands gather in shallow estuaries and river mouths such as those of Hudson Bay, where the warmer water helps calves and where the whales rub on gravel to shed their old skin.
In winter they move to areas of loose pack ice, keeping to cracks and openings to breathe. Belugas can also travel far up rivers, and small, isolated populations live year-round in Cook Inlet, Alaska and the St. Lawrence River in Canada.
Belugas eat a wide range of fish including salmon, herring, cod, capelin and flounder, as well as squid, octopus, shrimp, crabs and clams. They swallow prey whole, often using suction to pull it from the seabed.
They usually feed in water less than 300 meters (1,000 feet) deep but can dive beyond 700 meters (2,300 feet). An adult eats about 2-3 percent of its body weight each day.
Belugas are highly social. They usually travel in pods of 2-25 animals, often of the same age and sex, and these pods merge into summer gatherings of hundreds or thousands. Mothers and calves form especially close bonds, and calves nurse for up to two years.
They are curious, slow swimmers that often spyhop to look around above the surface. Their echolocation is precise enough to find breathing holes in the ice from below.
The beluga, Delphinapterus leucas, is the only member of its genus. Its name means "white dolphin without a wing", a reference to the missing dorsal fin. Its closest living relative is the narwhal, and the two species occasionally interbreed.
The IUCN lists the beluga as Least Concern, with a global population of roughly 150,000-200,000. Some local populations are in serious trouble: the Cook Inlet belugas of Alaska number only about 300 and are listed as endangered in the United States, and the St. Lawrence population remains far below its historic size.
Threats include the loss of sea ice, pollution that builds up in their fat, underwater noise from shipping and industry, and oil and gas development. Indigenous communities hunt belugas for food under managed quotas.
