All living patellogastropods have cap-shaped shells. The apex of the shell is typically situated at the center of the shell or slightly towards the anterior. All shells are sculpted with concentric growth lines; in many species, additional radial ribs extend from the apex to the shell margin. These ribs may be very fine like growth lines or broad and strongly raised off the surface. The shell aperture is typically oval. The inner surface of the shell bears a horse-shaped muscle scar that opens anteriorly where the head is located. The head has one pair of tentacles and the mouth opens ventrally for feeding on the substrate. Inside the mouth is the radula. The patellogastropod radula has very few robust "teeth," which are brown in color because of the presence of iron compounds. Patellogastropods have two gill configurations: in the Patel-lina, the gill is located around the edge of the foot and extends around the aperture, while in the Acmaeina, the gill is located over the head, as it is in other gastropod species.
Patellogastropods range in size from about 0.19-7.8 in (5-200 mm) in length. The smallest species and the largest are typically found in the lowest intertidal zone or subtidally. Most species in the intertidal zone average between 0.78-1.5 in (20-40 mm) in length. Subtidal species are typically white or pink in color and intertidal species are typically drab brown or gray with white spots and radial rays. Coloration in patel-logastropods is closely associated with their diet, and often the shell is similar in color to the substrate on which the limpet occurs because of the incorporation of plant compounds into the shell.
Was this article helpful?