By Hayley Dunning and Lisa Hendry
21
An exotic colour at the far end of our visible spectrum and often associated with royalty, purple is relatively rare in nature.
But some vibrant plants, animals and fungi do show off a regal purple, using it to warn predators, attract pollinators and protect themselves from the Sun.
Discover 10 examples of powerful purple wildlife below.
Violets (Viola species)
Violet by name, violet by nature, the genus Violais a perfect example of purple in the natural world.
Purple is common in plants, largely thanks to a group of chemicals called anthocyanins. When it comes to animals, however, purple is more difficult to produce.
Mammals are unable to create pigments for purple, blue or green. Birds and insects are only able to display purple through structural colouration. This is where tiny structures in the feathers of birds or the scales of butterflies and beetles are used to reflect light a certain way to appear coloured, even though the cells are actually colourless.
Violet coral (Clavaria zollingeri)
Despite its name and appearance, the violet coral is actually a fungus living in areas of unfertilised grassland rather than reefs. It often clusters near hardwood trees and gathers nutrients by breaking down organic matter.
While widely distributed across Australasia, Asia and North and South America, the violet coral is rare in Europe and listed as a vulnerable species in Britain.
This is because its preferred habitats - unfertilised lawns, churchyards and other semi-natural grassland - are under threat, mainly due to fertilisers in agriculture and gardening.
Purple dye murex (Bolinus brandaris)
This sea snail isn't purple itself, but if disturbed it secretes a substance that gradually turns purple.
As the name 'purple dye' suggests, the murex's secretion has been used as a fabric dye for thousands of years. In ancient times the dye was expensive to produce, so it was reserved for royalty. This association of the colour purple with royalty and luxury persists today.
Purple emperor (Apatura iris)
The purple emperor - often nicknamed His Majesty by butterfly enthusiasts - typifies the royalty of the hue.
How purple His Majesty appears, though, depends on your point of view. The tiny transparent scales of the butterfly's wings feature tiny shapes that scatter light, causing the wings to look purple. When not in direct light, however, the effect is lost and the wings appear brown.
Despite the royal nickname, the purple emperor has some downright filthy habits. It shuns flowers in favour of rotting flesh, muddy puddles and even human sweat, and spends its time getting into drunken brawls for females, fuelled up on oak sap.
Purple Honeycreeper (Cyanerpes caeruleus)
As with the purple emperor butterfly, it is the male purple honeycreeper that is decked out in violet-blue hues. The female isn't dull either though - she's a bold green.
Bright green is actually good camouflage in the honeycreeper's native Amazon rainforest, but the purple of the male is all for show.
The bird world is full of vivid male colours. Females often rely on them to gauge the fitness of males, and males use colours to compete for territory and dominance.
Purple sea star (Pisaster ochraceus)
Purple sea stars are a common sight along the Pacific coastlines of North America. They have few natural predators.
Recent research has shown the sea stars should be able to cope better than many sea creatures with ocean acidification, the result of rising carbon dioxide levels in the atmosphere. The species is able to grow additional fleshy tissue to compensate for a lack of calcium carbonate with which to build its external skeleton.
The animal is considered a keystone species for some places: its disappearance would have a profound impact on the diversity of wildlife in the local environment. This is because purple sea stars are the main predators of mussels that can overwhelm ecosystems if their numbers are left unchecked.
Purple frog (Nasikabatrachus sahyadrensis)
When researchers discovered it in India in 2003, the purple frog was declared not only a new species, but the sole representative of a new family.
Its closest relatives are four tiny species of frog in the Sooglossidae family that live on the islands of the Seychelles - 3,000 kilometres away - giving scientists clues to their evolutionary history.
Purple frogs spend a lot of their time burrowed underground, emerging only briefly during the monsoon season to mate. Even then, the males stay in their tunnels and call out from below a thin layer of soil.
Aubergine (Solanum melongena)
The aubergine's purple colour comes from anthocyanins in the skin.
Anthocyanins are present in many plants. They serve as sunscreen against the Sun's harmful UV rays, but they are often masked by the green colour of chlorophyll in leaves.
However, certain plants do show off their purple colour. For example, the purple, red or blue anthocyanins in some flowers attract pollinators by strongly absorbing light in the ultraviolet range, which insects use to see, making the plants stand out.
Aubergines vary in colour naturally and people have used this to breed aubergines in many different shades of purple.
Imperial Amazon (Amazona imperialis)
The imperial Amazon (or sisserou) is a parrot that lives in only one forested area of Dominica. Fewer than 250 birds remain in the wild. It is Dominica's national bird and features on the nation's flag, making it the only sovereign state flag in the world to feature the colour purple.
This distinction has earned the imperial Amazon some serious conservation efforts, including the protection of its natural habitat and a crackdown on the bird trade.
Purple sea slug (Hypselodoris bullockii)
The purple sea slug is a nudibranch - a large group of marine molluscs that have lost their shells. For defence they rely on their often unpleasant or toxic secretions, as well as the extreme colours that warn predators to avoid them.
All nudibranchs are elaborately decorated, but the purple sea slug comes in one of the widest varieties of colours for a single species, ranging from a pale yellow to vivid violet.
