Slender Pond Snail

Omphiscola glabra

- Slender Pond Snail

Description/identification

A small aquatic snail, typically 12-25mm longs, with an elongated brown conical shell. They have a small shell aperture, around one third of the total shell height, and do not possess an operculum. They can often be found on the underside of logs or tree roots, especially during the summer months when the water levels are low. They are best searched for using a kitchen sieve and sorting tray.

Habitat

Slender Pond Snail inhabit a range of freshwater habitats including ponds, marshes, small ditches or seepages. A key require in all these habitats is that they must dry up or the water level must significantly diminish in summer months. This ensures they have few competitors, as only specialists are able to survive these variable and harsh conditions. They are typically found in sites with very clean water (naturally low nutrients).

Life Cycle

Much like many molluscs, Slender Pond Snails are hermaphrodites. During the winter they lay between 10-30 eggs, which take 25 days to hatch. Due to the temporary nature of their habitat they are dependent on weather conditions, prolonged draught or flooding can cause fluctuations in their numbers. Although they are well adapted to drought and will burrow into the mud up to 6cm until their habitat once again fills with water.

Distribution and threats

Slender Pond Snail is listed under section 41/42 of the 2006 Natural Environment and Rural Communities (NERC) Act and is priority species for conservation. They were once widespread in the UK, but have declined significantly in the last 25 years. They still have some strongholds in Yorkshire, Cheshire, the New Forest and the West Country. However they may even be declining in these areas.

The main causes of their decline have been from loss or degradation of temporary ponds through infilling, pollution from agricultural run-off, scrub encroachment and over grazing. The small ephemeral habitats that Slender Pond Snail inhabit are often overlooked or their importance to freshwater wildlife not fully realised.