Rock Platforms: Spray Zone - Barnacle Ecology
The surf barnacleCatomerus polymerusis common on open coasts of south-eastern Australia, particularly where wave action is strong.
Adults are sedentary, but larvae float in the plankton, and may travel many kilometres from the parental shore.
Larvae metamorphose and are distributed by wave splash onto the rocks.
Initially larvae explore over short distances before selecting a position to anchor, grow a test, and settle for life.
Think of some reasons why internal fertilisation is characteristic of barnacles living in the spray zone.
Waves splash barnacle larvae onto the shore where they settle, secure themselves to the substrate with a glue produced by a special gland, and secrete the test. Photograph by Jo Smissen.