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Where is blue colour found in nature?

Where is blue colour found in nature?

Blue is one of the primary colours and it can be found in abundance across the natural world. From the clear blue skies and deep blue oceans, to the brilliant azure of tropical birds and butterfly wings, blue is a prevalent pigment in nature. In this article, we will explore some of the most common and striking examples of naturally occurring blue colouration across different species and habitats.

Blue in the Skies and Oceans

Some of the most ubiquitous sources of blue in nature are the sky and bodies of water. On a clear day, the sky presents as a vivid azure blue. This colour is caused by the way air molecules in the atmosphere scatter sunlight. Shorter wavelengths at the blue end of the visible light spectrum are scattered more widely by these air molecules, making the sky appear blue from the surface. With increasing depth in large bodies of water, visible light becomes increasingly absorbed, leaving only the penetrating blue wavelengths. This causes clear oceans and lakes to take on a deep blue shade.

Blue Pigments in Plants

While green is the most common pigment produced by plants through photosynthesis, some plant species also contain natural blue pigments. These blue pigments, called anthocyanins, are water-soluble flavonoids that occur in the tissues of certain fruits, leaves, stems, and flowers. Food plants that contain anthocyanins and exhibit blue colouration include blueberries, concord grapes, purple cauliflower, some varieties of purple sweet potatoes, and purple corn. Many spectacular blue flowers also contain these pigments, such as morning glories, hydrangeas, iris, delphinium, and pansies. The production of anthocyanins in plants is influenced by environmental factors and provides protection from damage by absorbing harmful wavelengths of light.

Blue Feathers in Birds

Vivid blue colouration can be observed in the plumage of some species of birds. Notable examples include blue jays, bluebirds, indigo buntings, blue-footed boobies, and the Steller’s jay. The blues and azures exhibited in bird feathers are created through the interaction of light with specialized nanostructures. The medullary keratin found in blue feathers contains an irregular array of air cavities and melanin granules that selectively reflect blue wavelengths. This structural coloration produces brighter and more saturated shades than the pigmentary colors created by other feather pigments. Additional hues and variations can be achieved by incorporating other melanins and adjusting the layering of keratin and air pockets.

Blue Invertebrates

In addition to birds, a range of invertebrate species display brilliant blue colouration. Several types of butterflies and moths exhibit iridescent azure wing markings, including the morpho butterfly, Atlas moth, and blue pansy butterfly. This colouration is created through intricate microscopic scales covering the wings. Other vivid blue invertebrates include certain tarantulas, like the cobalt blue tarantula, that have blue hairs on their bodies and appendages. Some species of squid also have chromatophores that can be adjusted to flash bright blue as a form of communication or camouflage.

Blue Reptiles and Amphibians

While less common than greens, browns, and other earth tones, blue can also be observed among some reptilian and amphibian species. Several species of lizards have blue markings or colouration, such as blue-tailed skinks, blue-tongued skinks, and the blue spiny lizard. Some snakes may also exhibit blue, like the blue racer snake and the blue-lipped sea krait. Blue poison dart frogs are brilliantly colored amphibians that derive their hue from blue and yellow pigments in their skin. The pigments serve as a warning to predators of their toxicity.

Blue Fish and Aquatic Creatures

Underwater habitats are home to numerous species with vibrant blue colouration. Many species of fish exhibit blue tones, such as blue tang, bluefish, bluefin tuna, bluegill sunfish, and blue-streaked cleaner wrasse. Blue whale sharks are the largest fish species and have blue-grey colouring that provides camouflage in open water. Bright blue creatures also include some jellyfish, crabs, lobsters, shrimps, and coral species, which obtain blues through fluorophores or physical structures in their shells and exoskeletons.

Blue Minerals

While most originate from geological processes and rocks rather than plants or animals, there are also a variety of vivid blue minerals found in nature. Azurite is a deep blue copper-based mineral often found in association with malachite. Blue vitriol refers to the blue crystalline form of copper sulfate. Cobalt blue minerals include sphaerocobaltite and linnaeite, which contain cobalt. Vivianite is a hydrated iron phosphate mineral that typically occurs as blue crystals or crusts. These minerals form through various chemical reactions and crystallization processes involving their elemental components.

Blue-Staining Fungi

Certain species of fungi also exhibit a blue coloration due to the presence of psilocybin or other blue pigments. Hallucinogenic psilocybin mushrooms bruise or stain blue when handled due to the oxidization of psilocin. Some bolete mushroom species have pores that stain blue when damaged, while the mycelium of some other fungi may also stain blue. The blues appear when the pigments are exposed to air, not while the fungi are growing. Blue stain fungus found in timber is often a combination of different fungal species that give the wood a blue-grey coloration.

Summary of Blue Colours in Nature

In summary, blue colouration can be found across diverse organisms and habitats in nature. While not the most common pigment, brilliant blues stand out and play important functional roles in the natural world. Vivid blues in animals often serve as communication, camouflage, mimicry, or warnings. Blues produced by light scattering, nanostructures, pigmentation, and mineral content demonstrate the many ways this color can form through natural processes. From the sky to the sea, and across many living things, blue is an integral part of the planet’s colour palette.

Conclusion

Blue is a prevalent pigment and structural colour across many different elements of the natural world. The vivid blues found in species such as birds, butterflies, reptiles, fish, and fungi serve important biological purposes like communication, camouflage, mimicry, and warning coloration. Blue skies and oceans occur due to the physical scattering and absorption of light. Blue also arises in minerals and rocks through chemical properties and reactions. The diversity of blues found in nature arises from pigmentation, structural coloration, and light interaction effects that produce this vivid primary colour.