The Class Bivalvia is a highly successful and ancient taxon (the second largest inside Mollusca) including ~25,000 living species. During their long evolutionary history (first appearance in the fossil record: 500+ Mya) bivalves adapted to a wide range of physical-chemical conditions (e.g.: salinity, temperature, pH, oxygen concentration, pressure), substrates (e.g.: buried into sediments, attached to hard surfaces), habitats (e.g.: rivers, lakes, estuaries, intertidal zones, coral reefs, ocean banks, continental shelves, deep waters), biological interactions (e.g.: free-living, simbionts, parasites), and feeding habits (e.g.: filtering, scraping, predation). Bivalves can have strikingly different dimensions (from less than 1 millimeter to 1+ meter), and despite their apparently simple body plan, they evolved very different shell shapes, and complex anatomic structures, such as eyes and mantle modifications for host-attraction. One of the most striking features of this class of animals is their peculiar mitochondrial biology: bivalves have facultatively anaerobic mitochondria that allow them to survive prolonged periods of anoxia/hypoxia; moreover they show the only known evolutionarily stable exception to the strictly maternal inheritance of mitochondria. Such phenomenon is called doubly uniparental inheritance, and has been reported, so far, in 100+ species. Mitochondrial activity is fundamental to eukaryotic life and bivalves, thanks to their diversity and uncommon features, represent a great opportunity to expand our knowledge about mitochondrial biology, which right now is limited to a few species. An integrated approach is the only possible way to be successful in such endeavour, so it will be necessary to build a strong collaborative relationship between genomics and physiology.