Secluded by sallow bushes and clumps of great willow herb is a small pond. In the natural surroundings it looks a little contrived, being a raised wooden structure, bench height and pentagonal. Nevertheless it provides a quiet haven after a day of solid talking at the British bird fair.



The heavy warm air is now cooling and the clouds darkening. With casual curiosity I lift a white water-lily leaf the size of a dinner plate from the pond surface and peer underneath. Adhering to the underside, looking like a dark brown shirt button, is a tight coil of a ram’s-horn snail.

There are 14 species of ram’s-horns in Britain, all aquatic and brown with flat coiled shells. Compared with the shells, their bodies are diminutive: delicate, ruddy brown, with threadlike tentacles that waft in any tiny current.

Despite the apparent ungainliness of their physical construction, ram’s-horns are very successful animals and are found in just about every permanent still water body in the UK, although even the common species peter out in Cornwall, west Wales and Scotland. Perhaps the secret is haemoglobin, a rare chemical in molluscs, which they use to extract oxygen from the waters they inhabit.

This one is the Whirlpool ram’s-horn (Anisus vortex), identified by its size and the tight, even coils of its shell. Other lily leaves hide more ram’s-horns and long clear jelly blobs containing dozens of snail eggs.

There are two other species obviously present: the deeper-bodied and more thickset margined ram’s-horn (Planorbis planorbis) and the even more heavily built great ram’s-horn (Planorbarius corneus). The latter is easily the biggest native, up to 3.5cm in diameter, the nearest thing to a living British ammonite.

I find these enigmatic water dwellers charming, but for me they also evoke fond memories of dashing around the Norfolk Broads, delving in weedy ditches, ponds and lake beaches for snails for a university project and later working to help conserve the little whirlpool ram’s-horn snail (A vorticulus), an animal on the verge of national extinction.

Follow Country diary on Twitter: @gdncountrydiary







