MICROTUBULES IN THE SHELL OF THE INVASIVE BIVALVE CORBICULA-FLUMINEA (MULLER, 1774) (BIVALVIA, HETERODONTA)

Using scanning electron and histological techniques on specimens of the bivalve Corbicula fluminea a new relationship between mantle, shell and periostracum has been observed, apparently for the first time. Here we demonstrate that several extensions of the mantle epithelium pierce the shell to join the inner layer of the two-layered periostracum. The mantle extensions are confirmed as unicellular processes. We suggest that they could serve the animal in the mobilization of calcium from the shell for buffering the extrapallial fluid under anaerobic conditions, when organic acids accumulate or when an extra contribution of Ca2+ is required.