Animals in the intertidal zones Barnacles Barnacles are known to secrete calcium-hard plates which essentially entirely encases them. These snow white cones have up to six very closely fitted plates that basically completely create a circle around the crustacean. Four completely other plates form what is known as the "door" which a barnacle can completely open or close on command. Depending on what the tide may be like. When the tide pushes and goes out, the barnacle will completely close to conserve all possible moisture. As the tides around the ocean come in however, a muscle opens up the four plates of a barnacle, and also the feathery legs of what is known as barnacle sift the water for food. All six pairs of these eccentric feather-like
