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

Using scanning electron and histological techniques on specimensof the bivalve Corbicula fluminea a new relationship betweenmantle, shell and periostracum has been observed, apparentlyfor the first time. Here we demonstrate that several extensionsof the mantle epithelium pierce the shell to join the innerlayer of the two-layered periostracum. The mantle extensionsare confirmed as unicellular processes. We suggest that theycould serve the animal in the mobilization of calcium from theshell for buffering the extrapalhal fluid under anaerobic conditions,when organic acids accumulate or when an extra contributionof Ca²⁺ is required (Received 5 January 1994; accepted 30 March 1994)