Many species of barnacles live in intertidal areas and are particularly well adapted to endure the stresses of long exposure at low tide. Barnacles extend their cirriand move them through the waer to absorb oxygen and collect food.
Cirri movements vary with environmental changes.
Barnacles are hemaphroditic, reproduce sexually and go through planktonic larval stages before attaching to hard substrates. Background Barnacles are one of the most common rocky shore intertidal marine animals. There are species of barnacles living in all intertidal zones, some are subtidal and some even live on whales. Some barnacles are parasitic and look so different from their free-living barnacle relatives that they were only found to be barnacles because of the presence of a typical barnacle cypris larva stage. But perhaps the most amazing barnacles are those that live in the upper intertidal zones, submerged only for a short time during each tidal cycle.