Why Are Beluga Whales White? How Their Color Changes With Age

How belugas change color as they grow

The name beluga comes from the Russian word for white, and the scientific name Delphinapterus leucas also ends with a Greek word for white. Yet no beluga whale starts life that way.

The change is gradual. As young belugas grow, the cells in their skin produce less and less melanin, the dark pigment that colors skin and hair in mammals. Females usually finish turning white a little earlier than males, at around 7 years compared with about 9, and the timing varies from whale to whale.

Because color follows age so closely, it is useful to scientists. During aerial surveys, researchers count the gray calves and juveniles separately from white adults to judge how many young are being born and surviving in a population. A white beluga beside a small dark one, as in many summer photographs, is usually a mother with her calf.

Why are adult belugas white?

The most widely accepted explanation is camouflage. Belugas spend much of the year among sea ice, ice floes and open leads, where a white body is hard to pick out against the ice and bright water. Their two main natural predators, orcas and polar bears, both rely partly on sight when hunting, so blending in may help adults avoid attack.

Many other Arctic animals use the same trick. Polar bears look white year-round, and Arctic foxes turn white for winter, as explained in why do Arctic foxes change color? The beluga is unusual because its color does not change with the seasons. Once an adult is white, it stays white.

Why calves start out gray is less clear. Scientists have not tested whether the darker color helps young belugas in any particular way, and it may simply reflect how pigment develops in the species. What is clear is that the switch from gray to white matches the beluga’s move into adulthood.

Is a white beluga an albino?

No. Albinism is a genetic condition in which an animal cannot produce melanin anywhere in its body. Albino animals are white or pink from birth and usually have pale or reddish eyes.

Belugas are different. They are born with normally pigmented gray skin, they keep dark eyes for life, and their white color appears only as they mature. Losing pigment with age is a normal, healthy part of the beluga’s life cycle, not a genetic fault. Biologists sometimes use the word leucism for animals with reduced pigment but normal eyes, but in belugas the white color is simply the standard adult coat.

The beluga’s summer skin molt

Belugas are one of the few whales known to molt their skin. Over the winter, the outer layer of the skin grows thicker and can take on a yellowish tinge, especially on the back and flippers. In summer, many belugas head into shallow, warmer estuaries and river mouths, where the old layer peels away.

A classic study in the Canadian Arctic, published in 1990, found that this molt is accompanied by a rise in skin temperature and faster growth of new skin cells. Researchers think the warmer, fresher water of estuaries helps belugas renew their skin quickly. Belugas have also been filmed rolling and rubbing against gravel on the bottom of shallow inlets in Nunavut, which seems to help scrub off the loose old skin.

NOAA Fisheries notes that some beluga populations molt this way every summer. The result is that by late summer, adult belugas look at their whitest. A yellowish beluga in spring is not sick or dirty; it is simply due for its yearly molt.

Other white whales

Belugas are the only whales in which every adult is white. Their closest relative, the narwhal, is born blue-gray and develops a spotted pattern, and very old narwhals can become almost white. In all other whales, a white animal is a rare individual rather than the rule.

Two famous examples show how rare that is. Migaloo, an all-white humpback whale first seen off eastern Australia in 1991, is thought to be a true albino. Iceberg, an adult male orca with a completely white body, was photographed near the Commander Islands in the Bering Sea in 2010. Scientists are still not sure whether Iceberg’s color comes from albinism or leucism. Such animals stand out precisely because they are so different from the rest of their species, while a gray adult beluga would be the true oddity.

Myths and facts about beluga color

Myth: baby belugas are white. Calves are gray at birth, and the white color comes years later, so a newborn looks more like a small gray dolphin than a white whale.

Myth: all white whales are albinos. Adult belugas are white without being albino, and even other white whales may be leucistic rather than albino.

Fact: you can roughly age a beluga by its color. Gray means young, pale gray means a teenager, and pure white means an adult.