The gill-leaflets each have a deep and densely-ciliated groove (1) around the rim . The respiratory inhalant water current is created by the motion of cilia on each leaflet drawing water in all around the shell, except at the gill-less anterior (X5000 scanning electron microscope images of cilia on a chiton at 18 Lepidochitona cinerea ). The oxygen-bearing water is drawn across the surface of the leaflets in the opposite direction to the blood flow within, so creating a counter current-system (Fretter and Graham, 1994). The dense cilia in the rim-groove are reported (Fretter and Graham, 1994) to propel debris particles caught on the leaflet surface to the free end where they drop off, but this would seem unlikely for those in holdfasts feeding upside down into the core of the stipe.
Concise
Part 1, SHELL FORMS: 02 Patella pellucida. Growth Stage 2 (GS2). July 2012. Littoral. North Yorkshire, England. © P. Lightfoot.
Part 2, BODY & ANATOMY: 03 Patella pellucida. Growth Stage 3 (GS3). 2009. Sublittoral, Farne Islands, Northumberland, England. © P.Lightfoot.
Part, 3 HABITS & ECOLOGY: 04 Patella pellucida. Length 4.6mm. Growth Stage 3 (GS3). September 2016. Yorkshire, England. © P.Lightfoot.