I’m dipping into one of our garden ponds on a glorious sunny day, as grasses, buttercups, wild blue geraniums, pink lady’s smock and red spikes of sorrel sway in the breeze. I’ve recently been on a workshop on microscopic pond life, where the tutor, Wyn, was well-practised at using a telescopic-handled golf ball retriever for reaching into the middle of ponds with a tiny sample pot. I bring back my catch and peer through a microscope at a single drop.
Rotifers, Desmidiales, Daphnia, Volvox and tardigrades: it sounds like the cast from Doctor Who. But these are a whole world of tiny organisms – some part animal and part plant, most measured in thousandths of a millimetre – that most people never see, and food for many creatures and plants further up the food chain. There are glassy, ghostly ovals, such as Euglena, which use flagellae to whiplash themselves along, or others that exude mucus in order to move.
There are long, flattened rows of algae with lime-green lipid globules – their own fatty food. Ciliates with tiny transparent hairs beating and wafting even tinier creatures into their mouths. So much variety. Many, like the spherical Volvox, spiral along with glass-like walls displaying their insides. And at this time of year they are all multiplying, due to higher temperatures and more sunlight.
My two ponds are only about 200 yards apart, but they have different suites of plants and ecology; at first I thought this was because one was acid and the other alkaline, but testing them, I find they are the same: pH 7.6. The bigger one next to the road has more pollution, but its ammonia and nitrates levels are near zero. Bog bean, spearwort and bulrush have choked one but died out in the other. Investigations will continue.
I’m reminded of pond-dipping with my brother many years ago. We made nets out of canes and mother’s old stockings. We took home a couple of jam jars and left them on the windowsill. Days later, long tubular things had grown, with a tentacled head and bits budding off. I suddenly remembered the diagrams I had drawn of Hydra for O-level biology. Ideally, children should be shown the real things first before having to study them.
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