Margined Ramshorn - Planorbis planorbis


Shell size: 9-18mm, height: 2.5-4 mm. A rather thick and strong shell. It is not glossy and it has a paler keel towards the periphery, past the mid-line but not right at the edge. There are 5 or 6 whorls which increase regularly in size. The mouth may be slightly expanded and sometimes bears a narrow rib inside.

Similar Species

The main confusion is likely to be with the Keeled Ramshorn, Planorbis carinatus, which also has a keel. They can be distinguished by the position of the keel and the profile of the shell joining the keel.  P. planorbis is flattened on one side with the keel very much at the edge with a rounded shell joining this keel. In P. carinatus the keel is off-centre but not right at one side with the shell more sloping at an angle to reach this keel.

Identification difficulty

Ponds, ditches, and in quiet slow flowing canals and rivers, usually in the shallower parts amongst the water weeds.

When to see it

All year round.

UK Status

It is found in most counties of England, and many in Ireland, but is recorded only infrequently from Wales and Scotland.

VC55 Status

Common in Leicestershire and Rutland.

Leicestershire & Rutland Map


Yellow squares = NBN records (all known data)
Coloured circles = NatureSpot records: 2020+ | 2015-2019 | pre-2015

UK Map

Species profile

Common names
Margined Ramshorn
Species group:
Slugs & Snails
Records on NatureSpot:
First record:
23/09/1987 (Rundle, Adrian)
Last record:
04/05/2024 (Nicholls, David)

Total records by month

% of records within its species group

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