Fly agaric

Rainbow nature: wildlife in ravishing red

Red is imbued with meaning for humans: it is the colour of danger, blood, attraction and romance.

And where crimson and scarlet hues appear in nature, they often carry an important message.

Red ladybird on a plant

Ladybirds can be a wide variety of colours, but red species like the seven-spot ladybird (Coccinella septempunctata) have captured our hearts © D Kucharski and K Kucharska/Shutterstock.com

 

Ladybirds (Coccinellidae family)

Ladybirds, with their distinctive spots, can be cream, yellow, brown, orange and black - but it is the red species that have captured public imagination.

Looking like tiny coloured jewels among plants, they are beloved by gardeners because many of them feed on plant-eating pests.

The cherry red shells are mainly for protection. Many species have chemicals in their bodies, making them taste horrible to predatory birds.

The more vibrant and conspicuous the colour of a ladybird, the worse it is likely to taste. Birds have learned this lesson, and are less likely to attack very bright ladybirds.

Red fly agaric

Although the colour of fly agaric marks it out as dangerous to us, it is not a universal rule that red means danger © UncleBucko, licensed under CC BY-NC 2.0

 

Fly agaric fungus (Amanita muscaria)

A bright red cap, complemented by white spots, has made this British fungus iconic.

Used in some cultures for religious and recreational purposes, it contains psychoactive alkaloids that cause hallucinations if eaten by humans.

But other toxins inside its cap can also cause excessive sweating, vomiting, and in severe cases even death.

In this fungus, the red cap is a sign of danger for humans - but it's not a universal rule. While fly agaric is deadly, many other red mushrooms, such as the scarlet hood, are fit for consumption. 

Black widow spider guarding an egg case

A red hourglass shape on the belly of a black widow spider warns predators to stay away © Chuck Evans, licensed under CC BY 2.5, via Wikimedia Commons
 

Black widow spiders (Latrodectus species)

These spiders have gained a reputation for being dangerous, but despite a painful prick and unpleasant reactions, a bite is not usually fatal to humans.

The spider's venom is usually used for subduing prey, but an attacker could also receive a nip.

A red patch on the spider's underside acts as a bright warning to stay away - a technique used time and time again in the animal kingdom.

Studies have revealed that red is associated with aggression and dominance in fish, reptiles and birds.

For humans, it is a more nuanced colour. Flushed cheeks can either be an angry warning, a show of pleasure or a sign of embarrassment.

Red leaves

Some leaves turn from green to red as the seasons change © Hermann Falkner, licensed under CC BY-NC 2.0
 

Wild grape leaves (Vitis sylvestris)

The grapes of wild vines were used to make wine before other species were commercially cultivated.

Before these leaves fall in autumn, they lose their green chlorophyll, leaving behind the beautiful colours of carotenoid pigments inside.

Carotenoids are the most common pigment in nature and are usually yellow, orange or red.

Most animals that sport these colours get them by eating plants and algae. Only plants, algae, aphids and mites are capable of making carotenoid pigments.

Scarlet ibis

The scarlet ibis gets its colour from the food it eats © Jurie/Shutterstock.com

 

Scarlet ibis (Eudocimus ruber)

Native to South America, the scarlet ibis lives in mangrove swamps, mudflats, shallow lakes and wetlands.

Almost every centimetre of this bird's body is a block of red, apart from a black bill and black wing tips.

The ibis gets its colour from eating shrimp that have ingested algae containing carotenoids. If the birds are fed on a diet lacking carotenoids, their red colour fades.

Red crabs

Millions of red crabs gather on the shores of Christmas Island every year to mate © christmasislandcrabs.com

 

Christmas Island red crab (Gecarcoidea natalis)

These striking creatures occur in their millions in the forests of Christmas Island in the Indian Ocean.

Each year they must migrate to the coast to breed. As the crabs reach the sea, the beaches of the small island become a moving blanket of scarlet shells.

A poppy field

Poppy fields can be an emotive sight because we associate them with the wartime deaths of soldiers © Piotr Kamionka/Shutterstock.com

 

Poppy (Papaver rhoeas)

The blood-red poppy has become a symbol of mourning and remembrance across the world, because of the significance attributed to the flower after World War One.

It has been used since 1921 to commemorate military personnel who have died in war, making it one of the most politicised and emotionally evocative flowers in the world.

Poppies are just one of a huge range of red flowers found across the world.

We can thank bird pollination for most of the red flowers that we prize in cultivation. The colour red often attracts birds, while white, yellow and blue attract insects.

Cephalotes atratus

The abdomen of this normally black ant is turned berry red by a parasite © Stephen P Yanoviak

 

Ant (Cephalotes atratus)

Miniscule parasitic worms (Myrmeconema neotropicum) turn the rear end of this normally black ant into a red bulb, making it look like a ripe red berry.

Scientists think this change in colour is a trick, to dupe birds into eating the ant.

If this happens, the bird gets a mouthful of the parasite's eggs, and eventually spreads them in its faeces. The droppings are full of seeds, and are gathered by other ants. The next set of unwitting ants then become infected, continuing the parasitic life cycle.

Open tiger tree seed pods showing the red seeds

The colour red attracts birds to flowers, fruits and seeds, such as those of the tiger tree © Catchlight Lens/Shutterstock.com
 

Tiger tree seeds (Erythrina folkersii

Plants use colour to help them spread. Some have special markings only visible to the insects that can pollinate them. Others make their fruits or seeds attractive to other species so they will be eaten and dispersed.

Birds are attracted to the red seeds of the tiger tree. Some birds eat the seeds, digest them, and then disperse them in droppings.