Marine Species Identification Portal : Lacuna vincta

(Montagu, 1803)

Description (shell):
Shell thin, with five to six tumid whorls; periostracum thin, though thickened patches may line sutures. Shell smooth to the naked eye, but with fine spiral ridges and prosocline growth lines. Umbilicus conical, with a prominent groove or chink bounded on apertural margin by inner lip, and on abapertural side by upturned outer lip; umbilical groove smooth, aperture below drawn out and slightly angular (L. vincta-drawing).

Size:
Up to 10 x 5 mm.

Colour:
Pale horn colour with two to four red-brown bands on last whorl; upper whorls with two colour bands, becoming faint towards apex which is generally purplish. Banding occasionally faint or absent.

Animal:
Snout long, broad, with slender cephalic tentacles arising from base. Foot elongate, with double edged anterior margin; two short, flat metapodial tentacles project from below operculum (L. vincta-animal).

Habitat:
Common on seaweeds, occasionally on Zostera , at LWST, sublittorally to 40 m. Tolerant of salinities down to 20 ä.

Distribution:
A circumboreal species extending south in Europe as far as the Channel and, less frequently, the Atlantic coasts of France. On suitable weed-covered shores on all British and Irish coasts and off Helgoland (Distr. L. vincta).

Lacuna vincta