Qualitative and Quantitative Study of Spiny Starfish (Marthasterias Glacialis) Footprints Using Atomic Force Microscopy

Starfish produce a strong, temporary adhesive from their tube feet. To detach from a substrate surface, they secrete a deadhesive, leaving behind the adhesive in the form of a footprint. Atomic force microscopy was used to investigate the physical and mechanical properties of the footprints produced by the spiny starfish, Marthasterias glacialis, using height imaging and energy dissipation. The adhesive material was found to be multi‐layered, composed of a homogeneous film and spongy meshwork of similar mechanical properties, covered with a gel‐like matrix supported by a web of interweaving fibres. Contrast in mechanical properties between the meshwork and the gel‐like matrix was detected, as well as within the matrix between the fibres and the surrounding material. The results presented here correlate well with previous research investigating the heterogeneous structure of starfish adhesive footprints. The structure is complex at the micro‐ and nanoscale, and the use of quantitative and qualitative atomic force microscopy techniques, under native conditions, has provided insight into the function of the secretion as a whole.