Why mussel byssal plaques are tiny yet strong in attachment

Mytilus edulis, or blue mussels, are known for producing byssal threads, allowing them to adhere to substrate in tidal zones. A byssal thread emerges from body tissue and terminates with an adhesive plaque. These byssal plaques are found to be tiny relative to the overall mussel size and do not vary much with different body sizes. In this study, we combine mechanical testing, 3D printing, and numerical modeling to investigate the effect plaque size has on adhesion strength. Our study reveals that the plaque structure governs the adhesion strength of the plaque, while plaques with a diameter three to five times that of the byssal thread yield optimized strength to resist detachment. Furthermore, bonding strength relies on the architecture of the byssal network rather than increased plaque size. Such knowledge helps to understand the design principle of byssal plaques and may shed light on designing reinforcement systems to secure engineering structures.