Settlement of barnacle larvae: surface structure of the antennular attachment disc by scanning electron microscopy

The surface morphology of the antennular attachment disc of the cypris larva of Balanus balanoides has been investigated by scanning electron microscopy, and its function is considered in the context of settlent behaviour. It is concluded that the attachment organ acts as an adhesive pad for temporary attachment while the larva explores the substratum. The surface of the disc is covered with villi, which could retain an adhesive substance thought to be produced by the antennular glands. The open-ended hair of the axial sense organ on the disc is shown.