Tidepool Tim says,  “Barnacles produce their own super-cement, and never move a day in their lives! They’re very stubborn crustaceans. They even molt! They close their shells at low tide, then open their mouths to feed when submerged in water. Feather-like feedings legs come out of their mouths and collect phytoplankton from the surrounding water. The legs also act as gills and gather dissolved oxygen. Take a close look at a barnacle underwater, then move your hand near it and watch the feeding legs retract. Barnacles don’t have eyes, but they can sense the change in light exposure using photoreceptor cells.”