Water flow inside the shell of Mytilus galloprovincialis was measured by phase-contrast magnetic resonance imaging (MRI). In seawater without algal cells at 23 °C, water approached the mussel from the posterior-ventral side, and entered through the inhalant aperture at a velocity of 40-20 mm s(-1). The flow rate in the lower mantle cavity decreased to 10-20 mm s(-1), the water flowed in the ant...