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Color use in nature
Nature is very colorful, full of different hues（色调）that delight the eye. What makes these colors and why do they exist?
Causes of Colors in Nature
Colors in nature are formed in two ways. Pigments, like the melanin in skin and many animal furs, produce most blacks, browns, reds and yellows. Most plants are green due to chlorophyll（叶绿素）. Other colors are caused by structure, like many greens, blues, and whites. Blue bird’s feathers actually contain black pigment, but their structure causes them to appear blue. The scattering of light by tiny dust particles in the air, viewed against the black background of space, makes the sky look blue too.
Color Use in Plants
Color has a great effect on the survival of plants and animals. Flowers have bright hues and patterns to attract insects. These insects move from one flower to another, making sure seeds are produced. Bees can see colors we cannot, i.e. ultraviolet, and follow these patterns of stripes or dots to the inside of the flower.  
Not only flowers but also fruits use color for the good of the plant. An unripe fruit mixes in with the leaves, but ripe berries contrast, becoming more appealing to the creatures who eat them. Birds are especially drawn to red fruit, and in turn help the plant by broadcasting its seeds.
Camouflage（伪装）in Nature
Many colors and patterns camouflage animals who want to avoid enemies. Some animals have damaging shapes to break up their outline, so an enemy will not recognize them. The eye, a very recognizable animal characteristic, is often disguised by a black stripe or patch. Light color below makes up for the shadow on the underside of many fish, amphibians and mammals.
Some animals even change colors to better camouflage themselves, seasonally like the snowshoe hare.
Warning Coloration and Mimicry（动态伪装）
Warning colors make an animal more visible rather than hidden. These usually indicate a negative aspect of the animal, like the bad taste of a monarch butterfly, smelly smell or painful bite of a bee. Usually black and a contrasting color (white, yellow, orange or red) form a striking pattern in these creatures, and frighten their enemies away. Nature is tricky, though, and sometimes harmless creatures pretend the patterns of harmful ones to scare off animals living on meat too.  
Social Coloration in Nature
Sometimes coloration is important socially. Male birds, typically more colorful, defend their territories and attract females. Eggs may use color and pattern to remain hidden. When they hatch, parents feed the nestlings when they see the bright pattern in their gaping mouths.
Taking a closer look at nature throws light on how color is used in marvelous ways!

Color use in nature
_______ for colors in nature	Many colors are caused by  which produce most blacks, browns, reds and yellows.
Other colors exist due to   , like blue bird’s feathers, which appear blue but actually contain black pigment.
Color use in Plants	Flowers have bright hues and patterns to attract insects, and then insects’ moving from one flower to another makes seeds        .
Fruits use colors, ripe color for example, to protect and help    .
Color use in animals	Colors help many animals      their killers. For example, damaging shapes can break up their outline, so an enemy will not recognize them.
Some animals, like snowshoe hares,  change colors to camouflage them.
Using warning colors to make themselves more  , thus frightening their enemies away.
Harmless creatures          to be those harmful ones to scare off their enemies.
Social use in nature	Animals use colors to defend their territories and attract the        sex.