Changing color

Changing color
Sometimes, an animal’s camouflage won’t work if the habitat changes or an animal travels to another part of its habitat. A number of animals solve this problem by changing color.

Some animals change color as the seasons change. The willow ptarmigan, an Arctic bird, is mottled brown in summer and blends in with the ground, rocks, and plants. In winter, it is white with a black tail and nearly disappears against a background of snow and occasional twigs. In spring and fall, as it molts (sheds) old feathers and grows new ones, the bird is a mixture of brown and white—just like the patchy snow-spotted world around it.

Some animals change color within weeks or days. Many caterpillars change color as they grow, shedding a skin of one color to reveal another that can protect them better as they move about more to feed. Crab spiders can change color in just a few days to match the flowers in which they lurk. Bark bugs of Central America grow darker when moistened with water. This helps them blend in with rain-darkened tree trunks.

Some reptiles, fish, and other creatures can change color in just a few hours. Many tree frogs, for example, can go from green to brown. Horned lizards of the southwestern United States can change their brown and gray tones to best fit their surroundings. The flounder, a flat-bodied fish with its eyes on the side of its head, lies on the ocean floor and takes on the color and texture of the sandy, stony surface in as little as two hours.

Other animals work even faster. Many octopuses, cuttlefish, and squids can change color in less than one second. An octopus can change from solid red to multiple colors, or even white, to match its background. It can also change the texture of its skin to resemble sand or stones. A cuttlefish can make light and dark waves ripple down its back, reflecting the way sunlight shimmers in water.