Sem observations on the interfacial surface of the cement of the adult barnacle, attached to natural and synthetic adherends

Abstract

The barnacle, Chthamalus fragilis Darwin, is found attached to a variety of natural and man-made substrates in the marine environment. Bases of specimens of this species attached to the leaves and stalks of marsh grass, Spartina alterniflora, and to polyethylene films placed in the high intertidal zone of the marsh were studied by scanning electron microscopy in order to determine the interfacial features of the cement holding these animals in place. When removed carefully, the interfacial surfaces of the barnacle cement appeared as finely detailed replicas of the leaf surfaces and of the polyethylene film surfaces, mimicking the highly contoured surface features and peripheral interdigitations of the adjacent epithelial cells which compose the surfaces of the leaves and ‘crow's foot’ and linear perturbations in the relatively smooth polyethylene films. These observations indicate that the bioadhesive secretion of this barnacle species loses its liquidity and becomes a hardened adhesive cement. It is probable that this mold-like replication of adherend surface details contributes to barnacle adhesion by mechanical interaction between the barnacle cement and the adherend surfaces.