Barnacles (Balanus, Chthamalus) are ubiquitous marine animals that are found along shores throughout the world. They are crustaceans, and thus are related to crabs and shrimp. Though several species exist in Bartlett Cove, they aren’t easy to tell apart. Barnacles may dominate in the high intertidal or in some areas of low salinity where few other marine species can live. Some particularly hardy barnacles survived one 3-year experiment in which they were submerged in sea water for only one day every three months. There is also a local species which lives only on the skin of humpback whales. In the middle intertidal zone barnacles can get so crowded that they force each other into a tall, thin “pencilform” shape. Another local species found in deeper water can reach 8 inches in diameter and is probably the largest barnacle in the world.
Barnacles feed on plankton in the water and, in turn, are eaten by a number of predators, including starfish, dogwinkles, and ribbon worms. To feed, it sweeps the water with its legs, called cirri, and pulls in food and fans out wastes. Barnacles can usually be observed feeding in tidepools or just below the water line.