The walking group stop as they see me peering into a net. “Can we ask what you’re doing?” I explain that I’ve heard there were shells in this pond and have come to find out what they are. As we talk, a blue-bodied dragonfly circles over the water. I tell them what it is and say that it has chosen this mucky pool as its breeding patch, and is probably waiting for a mate to arrive. “Thanks for the nature lesson,” they say with a smile, and head on.
This pond isn’t easy to find. We have only a rough idea where to look. To get to it we cross heavily cropped grassland with tufts of heather and ground-hugging gorse in among which is petty whin. This is a member of the pea family whose yellow flowers are carried on stalks with vicious thorns. We see it because it’s still flowering, much later than the guides say to expect it.
The pond is scarcely bigger than many in an average suburban garden. Sheltered on one side by bracken, it’s a muddy hole that holds water all year round. We could so easily have walked by without seeing it. The clay here is thick and the water is coloured by it. Hoof marks show that the animals drink from it, and skids down the steep side suggest that at least one has taken a plunge.
I pull out a branch that’s been half-in the water for quite some time. As it dries, the tan oval shape of a lake limpet stands out. It’s only three millimetres in length. Tucked into the fissures of decaying timber are tiny white specks. These are pea mussels, Pisidium species, quite impossible to identify without a microscope, most not more than 2mm across.
The net brings up wandering snails, Radix peregra, and some Sphaerium bivalves. They are all small and thin shelled, just managing to survive here. For these snails, location is everything. None are the size they would be in less acidic water.
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