Adhesive Interactions Between the Tube Feet of a Starfish,leptasterias Hexactis, and Substrata

The tube feet of Leptasterias hexactis adhere to and release from substrata by chemical interactions. In our laboratory these podia adhered to substrata coated with the ubiquetous anionic saccharide films produced by marine bacteria. Podia also attached to moderately anionic glass, but not to uncharged surfaces. The adhesive epithelia of tube feet labeled heavily with ruthenium red, indicating they were anionic. Tube feet secreted footprint films that bound crystal violet, a cationic dye. Trypsin removed the films. Adhesion to marine surfaces was prevented by 300 units/ml of heparin, a glycosaminoglycan (GAG) that may have competitively inhibited the glue from binding exosaccharide marine films. Lectins that bind bacterial exosaccharides did not inhibit attachment. We propose that tube-foot attachments are nonspecific ionic interactions established by secreted proteinaceous films and released when secreted GAG's compete with the tube-foot epithelium for sites on the film. This system agrees with the duo-gland model for adhesion and deadhesion.