10 - Biochemical Interactions between Molluscs and Their Algal and Bacterial Symbionts

Abstract

This chapter discusses biochemical interactions between mollusks and their algal and bacterial symbionts. Host–symbiont interactions in mollusks, like those in other host–symbiont systems, may confer important nutritional advantages on the host. The chapter discusses the biochemistry of mollusk–algae, mollusk–chloroplast, and mollusk–bacteria symbioses largely from the perspective of the advantages gained by the mollusk host. The most studied symbiotic relationships among the Mollusca are those involving photosynthetic symbionts, either intact unicellular algae or isolated chloroplasts. These symbiotic relationships have been fairly well characterized in terms of species-distribution patterns (for both host and symbiont), the nature of the photosynthetically derived products that are translocated from the symbiont to the host, and the acquisition and turnover of the algal and chloroplast members of the partnership. The recent discovery of an oligochaete worm that contains bacterial symbionts suggests that the type of symbiosis described for bivalve mollusks and pogonophoran tube worms may occur in other invertebrate groups living in habitats where simultaneous access to oxygen and sulfide exists.