Differential tissue development compromising the growth rate and physiological performances of mussel.

Differences in the food acquisition rates and in the energetic costs of metabolism seem to affect the growth rate variability of mussels. The aim of this study was to analyze if the physiological performances responsible for such growth rate variability are accompanied by structural differences at tissue or cellular level in the main organs involved in energy acquisition (gill) and processing (digestive gland). Fast growers had higher cilia density and metabolic efficiency in their gill, and well-developed digestive tissue with barely no connective tissue or atrophy.