Revisiting Michael Pollan’s long read on the magic of building a pond recently, I was reminded of the idea, rooted in ancient Greek philosophy, which caught the imagination of 17th-century scientists determined to prove it was correct. The theory, called spontaneous generation, held that life could spring from non-living matter as if arising from dust. Want a scorpion? Place some basil leaves between two bricks and leave them to bake under the sun, and shazam! Venomous arachnids would appear.
The truth, as we know, involves much more fun: scorpions come into this world thanks to scorpion parents who have indulged in a “promenade à deux” courtship dance, after which the male, overcome by romantic sentiment, pours sperm into the female using an appendage beside his mouth.
The notion that living things appear out of nowhere is nutty, of course. But there’s one thing you can do to fool yourself into believing it’s true: go outside, dig a hole, fill it with water and wait.
Bricks and basil leaves were on my mind a few years ago when I visited Tommy Earley, a beef farmer whose land adjoins Lough Allen in Roscommon, at the foot of the Arigna valley. We stood at the edge of a pond he had carved out of one of his fields. The pool of rainwater had become enveloped with life and, in return, nature had taken hold of him.
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Earley described a species he knew little to nothing about until it appeared in his pond: the dragonfly. The female lays eggs in the water; and they hatch as larvae.
“One day, in summer, you’ll see larvae crawling up the side of a reed, and out of that little shell, you’ll see the dragonfly emerge,” he said. “You’ll see the shell cracking, the dragonfly emerging slowly – uncurling one wing, then uncurling another wing, same as you getting out of bed in the morning. Then, it uncurls the body. It’s still a lime-green colour, but it starts to pump the colour down through each of the segments in its body. It’s as if you had a train on a railway track and you had the lights off in all the carriages as it’s getting dark, and you then switch on the lights in the first carriage, then the second carriage, the third carriage, all the way down along. It’s absolutely fantastic to see that.
“Then the dragonfly takes off, and this thing that lived underwater can hover, fly backwards, vertically, and drop down. You can see that for yourself when you have a little pond. It is amazing.”
Any available space will do: in local schools, sports clubs, churches, back gardens or allotments, or any spare outdoor space in the workplace
Earley has created 19 ponds on his farm. Species turn up before water has even filled the hole. One morning he spotted swallows at the side of a new pond as the diggers were still pulling soil from the ground. Other times he is visited by ducks like the red-breasted merganser, a species that usually stays firmly put in Lough Allen. They clearly cannot resist the multiple watery temptations on Tommy’s farm.
Under a microscope, a single drop of pond water reveals a scene reminiscent of a packed nightclub, with tiny organisms dancing left, right and centre and vigorously bouncing off each other. First up are the near-invisible protozoa, which come in all shapes and sizes – some with tails and others covered in minuscule hairs.
Filamentous green algae called water-silk or “mermaid’s tresses” contain spirals of green; they use the sunlight to make their food, as do slow-moving “volvox” algae, which look like aliens’ heads with neon green dots for eyes. Oval-shaped paramoecium swim about in a spiral dance, searching for microbes to eat.
These infinitesimal organisms are the basis of what will mysteriously appear next: small aquatic crustaceans such as the mottled brown water hog-louse, which is ready to munch through any dead or decaying plants and animals that sink into the oxygen-depleted abyss at the bottom of the pond. Water hog-lice are eaten by minnows, sticklebacks, frogs, newts and birds such as herons and egrets. (When a dragonfly larva spots a hog-louse, it shoots out a hooked claw from under its head to harpoon the prey, which it then grasps tightly before crushing and chewing it with sharp, serrated mandibles.)
Native water plants will bring oxygen into the water to keep it healthy. A helpful guide for inspiration is the recently published Aquatic Plants in Ireland, which is packed with photographs and information about aquatic plants in Irish ponds, rivers, streams, ditches, bogs and lakes. It includes details about charming and pretty oxygenators for ponds, such as the ivy-leaved crowfoot, which thrives in shallow, cool areas, and the floating frogbit, which will attract the attention of damselflies and dragonflies.
Only a small percentage of people are fortunate to own farmland, but digging a pond, however small, is worth it for the cascade of positive effects it brings – not least as a focal point for people to gather. Any available space will do: in local schools, sports clubs, churches, back gardens or allotments, or any spare outdoor space in the workplace.
It’s simple: a hole with water into which an astonishing array of life is breathed. There is no mystery, but when you see the results up close, it’s almost hard to believe.