Rock Platforms: Spray Zone - Barnacles Feeding
Acorn barnacles have been described as 'a shrimp-like animal, lying on its back,
holding on by its head and kicking its food into its mouth with its heels' (attributed to Thomas Huxley). Photograph by Joanne Smissen.
Click on the legs of the barnacle.
Yes! These really are the legs. Modified for filter feeding, legs extend through the operculum when there is sufficient moisture.
Phytoplankton collect on hairs on the legs and are transferred to the mouth.
Now click on the closed operculum of another barnacle.
Well done. This operculum is closed. Opercula are composed of two pairs of calcium carbonate plates. When the opercula are closed, the animal cannot feed, but closure prevents them from drying out at low tide.