Shining ram's-horn snail  (Segmentina nitida)

Listed as Endangered on the GB Red List (RDB1) (3).

The shining ram's-horn snail has a smooth, glossy and iridescent shell (4), measuring up to 6mm across (2), with no more than 5 whorls. The outermost whorl (body whorl) is expanded and overlaps most of the others (4), with a heart shaped aperture(4).

This snail is found throughout Europe, reaching as far north as Scandinavia. In the UK it has undergone a severe decline and is now restricted to the Norfolk Broads, parts of the Kentish Stour marshes (5), and Pevensey Levels after formerly being fairly widespread throughout much of England and known from around 90 sites (3).

You can view distribution information for this species at the National Biodiversity Network Gateway.

Inhabits ponds and drains of grazing marshes with unpolluted, often calcareous water, preferentially choked with a rich aquatic flora in an advanced stage of plant succession(5).

Little is known of the biology of this species.

Although the precise causes of the decline of this species are not understood, the main threats are likely to be eutrophication resulting from fertiliser run-off, ditch clearance, and conversion of grazing land to arable, and the resulting reduction in the water table (3).

The Species Action Plan produced under the UK Biodiversity Action Plan (UK BAP) for the shining ram's-horn snail aims to promote the increase and expansion of existing populations and promote research into the ecology of the species (3).

The UK Biodiversity Action Plan for this species is available at UK BAP.

View information on this species at the UNEP World Conservation Monitoring Centre.

There may be further information about this species available via the National Biodiversity Network Gateway.