Acmaea tessulata (O F Müller, 1776)
Author & date of last revision: Steve Wilkinson on 10 July 2011
Collisella testudinalis; Acmaea testudinalis; Acmaea tessulata (O F M;
Conical shell up to 20mm long but usually smaller if it lives in the intertidal. It is cream, green or grey in colour with red brown markings. The inside is white with a chocolate coloured, horseshoe shaped headscar. The shell surface is reasonably smooth but has fine radiating and concentric lines.
Key identification features
Ecology and behaviour
Lives attached to stable stones with red algal growths (feeds on these). Eggs are laid in spring/summer attached in a mucus sheet.
Distribution and status
Northern species occurring in the northern half of British Isles to the north of Norway.