The small pond is “as flat as a mill-pond”.
Its surface is flattened by the cohesive tension of water molecules at the boundary of air and water, together with the force of gravity pulling its surface down.
The surface layer forms a sufficiently strong “skin” that tiny creatures cannot penetrate, so they skate or float or walk across the surface.
A spider’s leg, with its water-repellent hairs, forms a liquid, limpid, languid dimple that can be seen in the angle of light from the sky overhead. Microscopic water mites skate about on the surface. All is quiet and peaceful, warm and sunny.
Suddenly the surface tension is broken, from BELOW, by a small green frog with a sharp snout -using its sharp snout to quickly grab one of the tiny mites. It is so quick and accurate that it can suck in many surface creatures in short time. The frog is grey-green with three yellow stripes on its back, one central along its spine, and one running down each flank.
Overhanging the pool is a stand of grass, and on its blades are clear crystal beads of water drops, formed into that shape by surface tension.
The frog advances out of the pool onto the shallow sandy edge, cautiously wary of me. It eats some ants.
It hops back into the pool and swims effortlessly, with its strong back legs, towards a sandy island in the middle. It hops out and sunbathes for a few moments, enjoying the warmth on its back. I follow its movements.
Suddenly, the surface is tension is broken again, this time from ABOVE, by big fat raindrops falling from the rapidly darkening sky. There is a rumble of thunder. Within a minute, the calm “mill-pond” is a churning mass of intersecting ripples, choppy water and frothy bubbles of oxygen coming to the surface. Gone are the mites, the spiders, the beetles and pond-skaters.
The little green frog is nowhere to be seen. But he is in his home environment, safe beneath the raging torrent above, free to move wherever he wants, unseen and protected by the disturbed surface of the water.
After ten minutes the rain ceases and the pond surface is pulled flat again, by the forces of gravity and surface tension – a tight skin that small creatures cannot penetrate.
C Tim Taylor 2016