Rainbow nature: life in dazzling yellow
The colour of sunlight, gold and daffodils, yellow is often associated with warmth and optimism.
Where it appears in nature, bright yellow is hard to miss. Plants can use it to attract pollinators, but some animals use it as a flashy warning to potential predators.
Discover 10 examples of wildlife decked out in this arresting hue.
Wild daffodils (Narcissus pseudonarcissus)
Daffodils bursting through winter soil are usually a sign that spring has arrived. They bloom everywhere: gardens, fields, roadsides, and inner cities, heralding warm weather.
Wild daffodils are smaller than some varieties that have been cultivated by breeders and gardeners to be large and yellow.
Native flowers have petals that are paler than the sunshine-yellow trumpets.
Swathes of wild daffodils are becoming a rarer sight in the UK, but carpets of them blossom in an area of Gloucestershire called the golden triangle.
Fields and verges full of native daffodils attract hundreds of visitors every spring.
Crab spider (Misumena vatia)
These spiders can change colour from white to yellow by releasing a pigment into their outer layer of cells.
It is a useful hunting technique, as they often look for prey on pale or lemon-coloured flowers, such as ox-eye daisies and goldenrods, and can camouflage themselves to match their environment.
The colour change can take a few days to complete.
White-tailed bumblebee (Bombus lucorum)
Bees' bold yellow and black stripes help to protect them from predators.
Birds, for example, associate the colour patterns with past experiences of being stung and learn to avoid them.
This works so well for bees that some hoverflies mimic the distinctive pattern, gaining the protection for themselves.
Hoverfly (Volucella bombylans)
One hoverfly, Volucella bombylans, mimics the white-tailed bumblebee extraordinarily well, with a similar fluffy body and colour scheme. You can tell the difference between the two by looking other at features on the insects' bodies.
Bumblebees have two sets of wings, compared to one on the hoverfly, and much longer antennae.
Banana (Musa acuminata)
Bananas are cheap and widespread, and billions are eaten across the world every year.
There are hundreds of varieties, but the ones we are most familiar with turn from green to yellow as they ripen.
This is because the amount of green chlorophyll in the skin decreases over time, allowing the pigments underneath to show through.
Not all bananas end up yellow - some varieties become red or purple when they are ripe.
Fire salamander (Salamandra salamandra)
Glistening black and yellow, the fire salamander is most at home inside piles of damp leaves and mossy tree trunks, or under rocks and logs.
The animal's main defence system is a series of toxin glands on the skin. These glands contain neurotoxins that can cause muscle convulsions and hyperventilation if consumed.
The yellow spots are a clear warning to predators that taking a bite could be dangerous.
Golden shield lichen (Xanthoria parietina)
Rather than a single organism, this lichen is a close partnership between a fungus and a green alga. They grow together, so they look like one individual.
This species is yellow because of a pigment called parietin, which protects the lichen from harmful UV light rays.
Specimens growing in the shade can be much less bright - almost green - because the lichen only produces enough parietin to protect itself from too much light entering its inner layers.
Colour in lichens can also vary with the weather, because moisture causes the surface to become transparent, allowing the green algae underneath to shimmer through. This process is reversed almost instantly when the lichen dries.
Yellow warbler (Setophaga petechial)
Adult male warblers are a richer shade of yellow than females and young birds, especially during the breeding season, and some have chestnut speckles on their chests.
The birds are socially monogamous, but occasionally mate outside of the pair they have formed. Researchers think that the bright colour of the males helps to attract a female mate.
Yellow aphids (Aphis nerii)
Aphids and mites are the only animals that can produce carotenoids, despite these being the most common pigments in nature.
Their ancestors acquired the genes to do this from a carotenoid-producing fungus, in a process known as lateral gene transfer.
Brimstone butterfly (Gonepteryx rhamni)
It is commonly believed that the word butterfly came from the distinctive yellow of male brimstones, called butter-coloured flies by early collectors.
The upper side of the males is a strong yellow colour, while the females have pale wings with a green tinge.
All species of Gonepteryx make use of camouflage: when sitting on leaves, the paler undersides of the wings reflect or take on the green colour of the surrounding plants.