Animal

Country diary: rain reveals the creatures that walk on water


The sound of heavy rain lashing against the bedroom window woke me in the middle of the night: just what the garden needed. By morning, a plastic bowl outside the greenhouse door contained an inch of water, with what looked like rafts of pink dust floating on the surface. But this dust was alive, composed of hundreds of minute creatures called springtails, each about half the size of a pin head.

Springtails, having six legs, were formally classified as insects, but these days, due to new evidence from molecular biology, they are often placed in a distinct evolutionary lineage of their own called Collembola. A unique feature, possessed by many, is a seventh limb-like structure tucked under their tail, called a furcula, which can be flicked backwards with lightning speed, hurling the animal into the air to escape danger.

Watch a video of springtails

There must have been at least 2,000 gathered on the water surface, the largest concentration of animals I have ever seen in the garden. Some were using their furculas in an attempt to pole vault their way out of the bowl, bouncing off the sides and tumbling back with their legs in the air, like children on a bouncy castle.

How had they got there? I last used the bowl for washing flowerpots; most likely, they had been feeding and breeding on fungi in the decaying sludge as it dried up in the warm weather.

Then down came the first raindrops, splatting into their midst – the beginning of a furious bombardment. A waxy exoskeleton makes springtails waterproof and, being so small and light, they can easily walk on water. But as the level rose, torrential rain would have turned the surface into a maelstrom. The microenvironment where these minute animals survive, at the limit of unaided human vision, taxes the imagination.

Springtails exist in vast numbers in fertile soil, feeding on fungi and recycling nutrients.



Springtails exist in vast numbers in fertile soil, feeding on fungi and recycling nutrients. Photograph: Phil Gates

Now, in the morning sunlight, the survivors floated, huddled together in gently rotating rafts on the calm, sunlit surface.

With up to 100,000 individuals per square metre of soil, springtails are among the most abundant animals in the web of life that maintains its fertility. I tipped the bowl contents into the vegetable garden for them to carry on their good work.



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