Littorina littorea

(Linné, 1758)

Description (shell):
Shell solid, with five or six slightly tumid whorls; sutures shallow, in some specimens upper whorls may be flat-sided or even coeloconoid. Spire prominent, pointed, more so in young shells, though last whorl may occupy up to 85 %, of shell height. Shell may appear smooth, especially in older specimens, but has prosocline growth lines and numerous, slight spiral ridges; latter may be strap-like on last whorl. Aperture ear-shaped, outer lip arising tangential to last whorl; inner lip thick, reflected over base of columella. No umbilicus or umbilical groove (L. littorea-drawing).

Up to 32 x 25 mm.

Generally black or dark grey-brown, often lighter towards apex, with heavier pigmentation between spiral ridges; occasional red, orange, or white individuals occur. Columella region white, outer lip with a darkly pigmented band internally, contrasting with lighter pigmentation of throat.

Cephalic tentacles rather flat and broad, with many transverse black stripes and, ventrally, a single longitudinal line. Foot and operculum of typical littorinid pattern.

Common on all but the most exposed rocky shores; mainly intertidal, the upper range increasing with exposure, but extends sublittorally to 60 m in the north. In sheltered conditions it may he found undertaking feeding excursions over muddy shores; tolerant of brackish water.

Distributed from northern Spain to White Sea. On all British coasts, Dutch coast and Helgoland, though rare or absent in Isles of Scilly and Channel Isles (Distr. L. littorea).