Albino squirrel (left); albino owl (center); albino iguana (right)

PETER TRIMMING/FLICKR (CC BY 2.0) (SQUIRREL); PRWC/BARCROFT IMAGES/REDUX (OWL); STEVE COOPER/SCIENCE SOURCE (IGUANA);

STANDARDS

NGSS: Core Idea: LS3.A

CCSS: Reading Informational Text: 2

TEKS: 7.14B, B.6F

Creatures Without Color

Life is full of challenges for animals born lacking hue

ESSENTIAL QUESTION:  Why is coloring important to an animal’s survival in the wild?

This past spring, the Borneo Orangutan Survival Foundation mounted a special rescue mission. The foundation’s conservationists saved a young orangutan being kept in a cramped cage in a village on the Southeast Asian island of Borneo. Orangutans are endangered, so the group aims to protect as many as they can. But this one was even more special than usual. That’s because instead of having an orangutan’s typical reddish fur, she was completely white. The ape’s rescuers named her Alba, Latin for “white.” She’s the only known albino orangutan in the world.

Albinism is an inherited condition in which the body can’t properly produce colored chemical compounds called pigments. As a result, the skin, hair, fur, feathers, or scales of albino animals are mostly colorless. Without their typical coloration, these animals don’t usually fare well in the wild.

A RARE TRAIT

Albinism has been documented in at least 300 animal species in North America and in a wide range of species around the globe. But it tends to be rare—only one out of many thousands of individuals might have this trait. Albinism occurs in people as well. About one in 20,000 people worldwide have albinism, though certain populations have higher or lower rates.

Part of the reason for albinism’s rarity has to do with the genetics of this trait. Units of hereditary material, called genes, control the production of pigments. Pigment genes have different versions, called alleles. People and most animals inherit one allele from each parent. Alleles associated with albinism are recessive, which means that an organism will show the trait only if it inherits two albinism alleles.

Many people—about 1 in 70—and many animals carry one allele for albinism and one for typical pigmentation. These individuals are carriers for the trait. Because albinism is recessive, there is nothing unusual about their looks. But two typical-looking carriers can have offspring with albinism (see Passing On Genes).

TROUBLE IN THE WILD

Some evidence suggests that animals born with albinism don’t fare well in the wild. One reason is that a stark-white animal stands out in its natural habitat, unlike an ordinary-colored companion that blends in with its surroundings. That makes it easy for predators to spot and catch an albino animal. Some studies, for example, have found that owls are more likely to pounce on albino mice than brown ones.

JOEL SARTORE/NATIONAL GEOGRAPHIC CREATIVE (PORCUPINE); CHAIWAT SUBPRASOM/REUTERS (SEA TURTLE)

Albino porcupine (left); albino sea turtle (right)

Lack of color brings other problems too. Albino birds often have trouble finding a mate and are sometimes even attacked by members of their own flock. The birds may not recognize an individual lacking the usual markings as the same species.

The sun is another potential danger for albino animals. The pigment melanin—which creates tan, brown, or black coloration in many animals—can be important for protection from the sun’s damaging ultraviolet (UV) rays. In people, exposure to the sun signals the body to pump up production of this pigment. That causes skin to tan, which provides some defense against burns. Animals and people with albinism, though, don’t produce this pigment. That makes them especially susceptible to sunburns and possibly deadly skin cancers.

JOEL SARTORE/NATIONAL GEOGRAPHIC CREATIVE

Albino kangaroo

Albino crocodiles, snakes, and lizards face special difficulties. Reptiles are cold-blooded—they rely on external heat to regulate their body temperatures and often bask in the sun to warm themselves up. Albino reptiles can’t keep warm the typical way without the risk of sunburn. They tend to do better in captivity, where caretakers can provide artificial heat sources like special heated stones to keep them warm. 

THE EYES HAVE IT

Just because an animal’s coloring is pale doesn’t mean it has inherited albinism. “There are many naturally white animals, such as polar bears, that aren’t albinos,” says Murray Brilliant, a geneticist at the Marshfield Clinic Research Institute in Wisconsin. One big clue that an animal isn’t albino is dark-colored eyes. True albino animals don’t produce dark eye pigments.

BRUNO CAVIGNAUX/BIOSPHOTO/GETTY IMAGES

Albino rat snake

An ongoing study of squirrels across the U.S. is showing how the occurrence of white fur compares with that of true albinism. Of the squirrels reported to have white fur, the survey found that about 80 percent have dark eyes. Only about 20 percent have red or pink eyes that show they’re truly albino. “That pink color comes from blood vessels in the back of the eye,” says Brilliant. The same is true for albino rabbits and mice.

Other species with albinism, including people and orangutans like Alba, don’t have pink eyes—although camera flashes can sometimes make it look that way in photos. Since humans and other primates have more types of eye pigments than other animals, individuals with albinism tend to have eyes that appear very light blue.

DANITA DELIMONT/GALLO IMAGES/GETTY IMAGES (BISON); ROBERT HARDING/ALAMY STOCK PHOTO (LEMUR)

Albino bison (left); albino lemur (right)

Eye pigments and the molecules involved in making pigments are important for healthy eye development. Without them, animals with albinism can have serious vision problems, which can make spotting prey or predators difficult.

People with albinism often have vision problems too. In his research, Brilliant has identified alleles associated with albinism in people. “Now we’re working on understanding how the genes function and developing therapies to enhance vision in people with albinism,” he says.

BOS FOUNDATION/INDRAYANA

MEET ALBA: This albino orangutan will be kept safe on a special reserve.

Poor vision is just one of the problems that would put Alba, the albino orangutan, at risk in the wild. To keep her safe, conservationists plan to set up a spacious reserve for her to live in with three orangutan friends—a fitting home for a truly unique animal.

CORE QUESTION:  Create a Punnett square that shows the offspring of a parent with albinism and a parent carrying one allele for albinism.

Text-to-Speech