It is a murky, dank night in the middle of the countryside, a tawny owl is calling, and I am in raptures, stroking a slug. From the nearby blackness, Jeremy Buxton, a farmer, exclaims: “Oooh, an earthworm!. Oh, wow.”
The brown slug is emitting brilliant fluorescent yellow slime as I touch it; the earthworm is revealing twin tracks of turquoise on its belly. What might appear some kind of experiment with psychedelic mushrooms is actually a new way of seeing the world at night: shining ultraviolet torches to reveal the natural biofluorescence of animals, plants and fungi.
“We’re in a minority of animals that can’t see biofluorescence,” says David Atthowe, an enthusiastic naturalist and walker who has started guided night strolls with UV torches. “It’s a form of communication. We’re just not aware of it.”
We’re undertaking one of Atthowe’s walks on the wildlife-friendly fields of Buxton’s farm in the village of Booton, Norfolk, and it is a revelation.
Unlike bioluminescence, which is when an organism generates its own visible light via a chemical reaction, biofluorescence is the absorption of light by living organisms who then emit it as bright blues, greens, reds and yellows. Ultraviolet light has wavelengths shorter than those detectable by the human eye but UV torches bring it into our vision.
The scientific world is on a journey of discovery about biofluorescent communication. It has been documented among marine organisms including sharks for a while but until recently it was not known that many mammals glow with biofluorescence. North American flying squirrels shine brilliant pink, and Australian researchers this month revealed that 86% of 125 mammals studied had fur that glowed under UV light.
Budgies whose cheeks and crown were slathered in sunscreen to block UV light have been found to be less attractive to the opposite sex than those who were allowed to display their natural biofluorescence.
Atthowe discovered the phenomenon when he chanced upon a Ted Talk online. Since becoming fascinated by it, he has imported UV torches from China and tested them in habitats across Britain, including in temperate rainforests. This summer he launched night walks for small groups around East Anglia.
“It’s become this incredible journey of discovery,” says Atthowe. “Hedgehogs and moles are my two favourite discoveries this year. Not many black animals fluoresce but I found a dead mole and its fur was blue. And Sonic the hedgehog is totally real! Hedgehogs go blue as well. That’s exciting.”
We begin our walk in Buxton’s pastures where lichen that is yellow-grey by day is revealed as brilliant orange. Algae on fence posts that is unnoticed in daylight is now vivid red. Woodlice scurrying along a branch shine a luminous blue. Grass seeds glow aquamarine.
We peer into a hollow tree stump. “Last time I looked in, there was a little mouse and it was orange,” says Buxton. “So trippy.”
Spiders shine bright blue and yellow. Atthowe has noticed that harvestmen spiders are vibrant purple when they are young but change to a yellowy white as they mature.
The biggest surprise are nettles: those in sunny spots remain green but those in shadier areas have leaves of vivid red.
Buxton, who has the keen eye of a country person, spots a moth on the trunk of an oak. In “normal” white light it is grey-brown but under UV it shimmies with a subtle purple and pink. Lepidopterists have recently discovered that some butterfly chrysalises that are superbly camouflaged in daylight shine brightly under UV light – making the scientific monitoring of species such as the purple emperor much easier.
But the highlight tonight is the fungi. Beneath trees on the field edge, russulas show up bright lemon yellow. A bracket fungus, popularly known as artist’s conk, is brown with a creamy underside by day. Now, under our UV torches, it shows up bright duck-egg blue with a blood-red cap.
The UV light also reveals the ubiquity of human-made fibres, even in the middle of the countryside. Little threads show up bright blue and what appears to be spectacular lemon caterpillar in a bush turns out to be a lost scrunchie.
The evening is a tranquil experience. As one walker, Josh Bright, puts it: “You’re going smaller, you’re going slower, and you’re going on a different wavelength.”
For Buxton, the biofluorescent walks are another way of connecting local people with nature and with his farm. “Farms should be hubs for communities and learning. It’s getting people outside and engaging them with nature,” he says. “It’s so satisfying when you hear someone go: ‘Oh my god, look at that!’ It’s a whole new way of looking at nature.”
Atthowe, who has led biofluorescent walks beside coastal rockpools and on the Norfolk Broads, says each season brings new delights – fungi in autumn, lichens in winter and new flowers and caterpillars in spring.
When he began, he thought the 90-minute night walks should be 16-plus but he was deluged with requests from families and so he has opened them up to everyone aged eight and above.
“The energy the children bring is just amazing. I love it. It’s so accessible, anybody can do it, and you don’t have to be an expert,” says Atthowe. “You can make the most banal things seem like magic – nettles, alexanders flowers, even pigeons look amazing, shining pinky purple under UV.”