Barnacles

Barnacles are small crustaceans that attach themselves firmly to the rocks. They are relatives of shrimps, lobsters and crabs. The are protected by a calcite shell made of plates, two of which can be opened and closed like a gate. When the tide comes in and the barnacle is covered by water, the gate opens and the animal extends its feet which waft drifting algae and small creatures into its mouth. But barnacles are also prey to the dog whelk and edible crab which emerge from deeper water to eat them.