Bacterial Symbionts in the Epidermis of an Antarctic Neopilinid Limpet (Mollusca, Monoplacophora)

For the first time it has become possible to study a `living fossil' Laevipilina antarctica, a representative of the family Neopilinidae (Mollusca, Monoplacophora) by means of transmission electron microscopy. This led to the discovery of a bacterial symbiosis in the epidermis of the mantle roof and of the head of the animal. Bacteria with varying morphologies were found between the microvilli of the epidermal cells. In addition, modified and specialized epidermal cells (bacteriocytes) were detected in the mantle roof and the post-oral tentacles. In contrast, the sole of the foot and the alimentary tract of the animal are free of symbionts. The bacterial symbionts may be involved in the recycling of dissolved organic matter.