 The anterior part, the mesosome, has a cavity, the mesocoel, that extends into the tentacles and keeps them rigid by hydrostatic pressure.The mesosome bears the lophophore, a specialist feeding structure which consists of a ring of up to 190 translucent tentacles arranged in a horseshoe-shape encircling the crescent-shaped mouth.The posterior and larger body section is the metasome and contains the metacoel.