Marine mussels live in a variety of environments, be it on rocks hit by waves and tides, or partially submerged in the sand. To attach to rocks, piers, or other mussels they utilize their byssal collagen-rich threads that terminate in a proteinaceous adhesive plaque. We have previously reported [1] on the porous internal plaque architecture of marine mussels Mytilus californianus and Mytilus galloprovincialis, which bears similarity to structural foam architecture. Aside from the collagen that penetrates the plaque to create a thread-plaque junction, the plaque is composed of large pores (~1 μm) randomly dispersed in a dense meshwork (~100 nm scale) (Figure 1). Our observations subsequently inspired a 2d mechanical engineering model [2] that quantified the effect of periodically patterned porosity on adhesion on a plate adhered to a rigid substrate.

     We are interested in understanding the effect of porosity on plaque adhesion mechanics and whether there is a link between mussel genera, the forces they are subjected to at their endemic environment, and their respective plaque porosity. Towards this end, our ongoing studies have explored various mussel species and genera and show the fraction of large pores versus dense meshwork vary among them. In some cases, there is even no porosity observed. Our current efforts focus on quantifying the 3d porosity and the spatial distribution of pores in the plaques of different species via image analysis and stereology methods [3] in order to provide quantitative data for the future fabrication and mechanical study of (doubly) porous materials and as an input in 3d simulations.

References

[1] E. Filippidi; D.G. DeMartini; P. Malo de Molina; E.W. Danner; J. Kim; M.E. Helgeson; J.H. Waite; M.T. Valentine J.R. Soc. Interface, 2015, 12(113), 20150827.

[2] A. Ghareeb; A. Elbanna Journal of Applied Mechanics, 2018, 85(12), 121003.

[3] D.F. Susan Metallurgical and Materials Transactions A, 2005, 36A, 2481-2492