I didn't expect to find much, but curiosity beckoned. The water was bone-chillingly cold when I pushed the jam jar below the surface and dragged it through weeds and rotting leaves along the garden pond margin. What I saw when I held it up to the light was a revelation. Even before the detritus settled the crustaceans – frantic gammarid shrimps and trundling water slaters– began circling the bottom of the jar. Then scores of small black disks elongated, revealing themselves to be flatworms that glided effortlessly across the glass on a magic carpet of invisible cilia. Next it was the turn of pond snails, emerging from their shell coils, extending tentacles and hauling themselves upright, setting off to explore new surroundings.
They were all familiar from summer pond dipping, but it was a surprise to find so many, so active, in such a small sample in mid-winter. The novelty came from dozens of tiny castanet-shaped shells on the bottom of the jam jar: orb-shell cockles, some as translucent and fragile as a new-born's smallest fingernail. They were more cautious, extending a slender muscular foot between their shell valves then using it to punt themselves across the jar. When they came to rest their shells parted a little more and two short pink siphons extended, wafting water across their gills. A water flea, passing close, was swept aside by the current of expelled water.
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