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Adhesion of raphid diatoms to natural surfaces, which is mediated by the secretion of extracellular polymeric substances (EPS), is an important strategy for growth and survival and contributes to the economically important process of biofouling. An understanding of adhesion processes requires that the genes involved in the EPS biosynthetic pathways and their regulation be characterized. Phaeodactylum tricornutum provides a model system in which to do this but the quantitative adhesion characteristics of the various morphotypes and isolates of this species are currently unknown. The present paper reports on the use of a calibrated fully turbulent flow cell to characterize the whole cell adhesion properties of morphotypes and strains of this species. It has been shown that only the oval cell morphotype adheres to a surface. There are strain/isolate differences in adhesion strength: some strains including strain Pt 1.8.6, the genome of which has been sequenced, show adhesion strengths comparable to other raphid diatoms. In common with some other raphid diatom species, adhesion strength of oval cells of some isolates of P. tricornutum was greater on a hydrophobic surface (Silastic T2 silicone elastomer), than on hydrophilic acid-washed glass. These studies provide a baseline for future molecular genetic and gene expression studies. [ABSTRACT FROM AUTHOR]