Goose Barnacles are members of the Lepadidae Family that are also known as Gooseneck Barnacles and Stalked Barnacles. They get their name from naturalists in the 1500’s that believed these barnacles turn into geese. Our understanding has improved since then, and they are now in the Phylum Arthropoda, meaning that they have jointed legs. They are crustaceans, as are crabs and lobsters. They begin life as a planktonic, shrimp-like larvae, which settle out on the substrate, usually crowded in with many others of the same species, where they attach to a substrate and grow into adults. Adult barnacles consist of a “shell” or capitulum that is composed of five or six plates made of chitin, the same major component of crab and lobster shells. Contained within the capitulum are the head, thorax, and cirri (feathered legs). The head consist mostly of mouth parts with the plates opening, similar to a clam shell, to allow the cirri to extend. The cirri function like gills to extract oxygen, and plankton and detritus from the water for food by filtration. The plates are white in color and often become chalky over time and can reach up to 5.0 cm (1.9 inches) in length. The capitulum is attached to the hard surface by a stalk (peduncle) that is strong and rubbery, with either a leathery or scaly exterior, and may reach up to 50 cm (19.7 inches) in length.
Goose Barnacles may be found in the intertidal and subtidal zones along moderately exposed coastlines, or they may be found attached to buoys, flotsam, marine animals, or ships. They are frequently found by beach goers when flotsam wash ashore. Goose Barnacles feed on planktonic forms of algae, amphipods, copepods, detritus, hydrozoans, mollusks, and polychaete worms. In turn they are preyed upon by shore birds, crabs, and fish. While most Goose Barnacles are found in relatively shallow water, they can be found at depths up to 4,160 m (13,645 feet). They are found worldwide in tropical and temperate seas. There are 20 species in the Lepadidae Family or which 8 species are found along the Pacific Coast of Mexico.