Rapid vaterite-mediated shell repair for acid-induced damage in a deep-sea mussel

Mollusks are able to secrete and repair the most diverse and complex calcareous tissues in the animal kingdom, yet the detailed molecular mechanisms of these biomineralization processes, especially for the deep-sea calcifiers, remain to be elucidated. Here, using an in situ experiment, we report a repair mechanism for acid-induced shell damage via biologically mediated vaterite formation in the deep-sea cold-seep mussel Gigantidas haimaensis . Interestingly, the mussels secreted and recrystallized amorphous calcium carbonate into vaterite to seal the acid-induced dissolution porosities within 30 h. Calcium and nucleation substrates were potentially supplied by the mantle, including calcium-binding proteins and hydroxyapatite. Calcium then reacted with readily available carbonate in the extrapallial space, whose precipitation can be promoted by the nucleation substrates. This rapid repair mechanism is likely an advantage in the habitat of these mussels, which are characterized by pulsed acidification events from the seeping fluids. Furthermore, our finding expands our understanding of the diverse biomineralization mechanisms by which mollusks maintain their protective shells.