Many marine invertebrates have enormously complex surfaces which they depend upon for a variety of essential processes, including gas exchange, excretion, locomotion, food capture and sensation. Man-made materials placed in the sea are rapidly fouled by a succession of macromolecules, bacteria, microalgae and then (though not always) by macrofouling organisms such as barnacles and mussels. The seas are a veritable soup of microorganisms and larvae looking for somewhere to live. The large and organically-rich surfaces of marine invertebrates, such as echinoderms, would seem ideal habitats but many marine invertebrates prevent any biofilm formation on their surfaces. One possibility is that the physico-chemical properties of the surface prevents unwanted adhesion. Until recently it has only been possible to measure the surface properties of biological materials indirectly or using techniques (such as electron microscopy) that necessitate gross perturbations of the surface. By using surface science techniques such as Atomic Force Microscopy and FT-IR spectroscopy in conjunction with more traditional biological techniques (light microscopy and immunolabelling) it has been possible to identify the outermost molecular coatings on echinoderms as consisting of proteoglycans. The surface of echinoderms are thus very similar to endothelial blood systems and there may be common mechanisms in operation preventing unwanted adhesion by microorganisms and cells.