MolluscIreland - land and freshwater
  • Theba pisana (O.F. Müller 1774) Sandhill snail
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Theba pisana
© Dr Roy Anderson
Theba pisana
© Dr Roy Anderson

Map hosted by the National Biodiversity Data Centre, Waterford
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A medium to large, slightly depressed globular shell with 5½-6 slightly convex whorls and shallow sutures. Aperture elliptical with an internal rib. Surface white, yellow-brown to pink, with a complex and varied pattern of dark spiral bands which may be faint or broken up. Sand dunes on south and east coasts. Spreading.

Key characteristics

  • A medium large whitish, globular shell of 5½-6 whorls
  • Spire very low, whorls slightly convex and sutures shallow
  • Colour white to yellow-brown or pink with a complex pattern of brown spiral bands which may be interrupted or faint
  • Aperture elliptical with an internal rib
  • Umbilicus narrow, partly closed by the reflected columella
  • Surface with coarse growth ridges crossed by fine spiral striae

Size

16-22 mm.

World Distribution

A native of the Mediterranean but introduced to the coasts of north-west Europe as far north as the low countries and the British Isles.

Irish Distribution

Known since the nineteenth century from a small number of sites on the coasts of Louth, Meath and Dublin between Clogher Head and Rush (Kerney 1976a). More recently three colonies have been found in West Cork, at Garrettstown/White Strand, Ownahinchy Strand and Inchydoney Island (Cawley & Colville, 2001). It has also spread from its north Dublin sites to the North Bull sands in the city of Dublin (Anderson, 2008).

Ecology

  • Confined to coastal dunes in relatively frost-free localities
  • Has a predilection for climbing dead vegetation or walls during dry periods and remaining cemented in position for long periods by a copious chalky secretion used to block the shell opening and reduce water loss

Red List status

  • Not applicable.

Wikipedia link

Wikipedia page for Theba pisana

 Anderson, R., (2016). Theba pisana (O.F. Müller 1774). [In] MolluscIreland.
http://www.habitas.org.uk/molluscireland/species.asp?ID=167 Accessed on 2017-10-21.